Minggu, 31 Oktober 2010

Reasons for an Exhaust Guide Breaking

Exhaust guides lead a very difficult life. These copper, bronze or steel sleeves sit in between the exhaust valve's stem and the cylinder head, and they must absorb not only the tremendous friction created by the reciprocating valve but a fair amount of the exhaust heat as well. Even a tiny imperfection in material, fitment or installation can result in a broken exhaust valve guide and quite possibly engine failure.

Normal Wear

    An exhaust valve opens twice for every engine revolution and may travel as much or more than half an inch every time it opens. The exhaust valves in an engine running at 3,000 rpm slide through the valve guides at about 500 feet per minute. Over time, this will cause the softer valve guide to wear away, becoming thinner and more prone to cracking.

Factory Defects

    Car manufacturers don't get things right 100 percent of the time. The original valve guides may have been too thin or made of an alloy that tended to work-harden and crack over time. The factory may also have miscalculated the guide material's heat expansion characteristics. Material casting defects aren't uncommon either; even a tiny imperfection in the guide metal's crystalline structure can act as a starting point for cracks.

Overheating

    Overheating can cause a multitude of problems, most of them resulting from heat-induced metal expansion. As metal heats up, its crystalline structure widens before breaking down completely and melting. Different metals expand at different rates. Extreme overheating can cause a valve guide to expand far more than it should (causing it to clamp down on the valve or become warped) or cause the head to expand away from the valve. Either way, the valve guide weakens and eventually becomes prone to breaking.

High Exhaust Gas Temperature

    Valve guides act as a conduit to conduct combustion chamber heat away from the valve and into the cooling system. The extremely high exhaust gas temperatures experienced by highly boosted, turbocharged gas and diesel engines can create a temperature differential between the valve side of the guide and the coolant system side. The valve side heats up and expands more than the coolant system side, causing the guide to literally rip itself in two.

Improper Concentricity

    Under some conditions, the valve guide may go out of alignment with the valve seat. This lack of concentricity is usually the result of heat induced head warpage from overheating, welding on the cylinder head or improper machine work. Misalignment between the seat and the guide will cause the valve stem to flex every time the valve head meets the seat, putting a side load on the guide. This will cause premature guide wear and breakage, and in extreme cases can cause the valve itself to crack and snap. This lack of concentricity may also be a factory defect due to post-head-casting valve guide installation.

Sabtu, 30 Oktober 2010

Common Nissan Ignition Troubles

Common Nissan Ignition Troubles

Nissan, a multinational automotive manufacturing group based out of Japan, offers a myriad of vehicle styles ranging from compact cars and sedans to sports utility vehicles and vans. While well-built, Nissan vehicles commonly experience issues with their ignition. Knowing what to watch for in advance may help Nissan owners save time and money in the long run.

Faulty Ignition Switch

    One of the most common issues with Nissan vehicles is a faulty ignition switch. The ignition switch connects the starter to the battery; if it fails, the car will not turn over. Many times when a vehicle has a faulty ignition switch, a primary symptom will be difficulty in turning the key once inserted. Replacing an ignition switch can be costly, averaging $200 or more based on who performs the work, but before choosing that option, you should check the key. Sometimes a worn-out key can prevent the switch from grabbing. Replacing the key with a sharper, freshly cut key often corrects the problem.

Security Immobilizer Issue

    Many later-model Nissans are equipped with what is called an immobilizer, a security device that is designed to protect your car from theft. The immobilizer stalls the vehicle and prevents it from starting whenever an incorrect key is inserted into the ignition. If your Nissan fails to start after you insert the key, and a red key shape appears on your dash, this means that you may have used the wrong key. However, if after checking you determine that the key is correct and the vehicle still does not start, that may indicate a faulty immobilizer. In this case, only a trained mechanic should diagnose and repair the problem.

Ignition Fails

    Another common cause of a Nissan's ignition failure is a bad starter or battery. Because ignition switches connect the starter and the battery, failure of either of these components to perform can prevent the vehicle from catching on or running. Often times, when a battery or charger has gone bad, the vehicle's interior and head lights may dim, the air conditioner may fail to blow and the radio may die. If you car has any of these symptoms, chances are that a bad starter or battery is the culprit. However, if everything else seems to be working properly and the only issue is the ignition failing to start, then a certified mechanic will need to look over the ignition column.

Basic Automotive Electrical Troubleshooting

Basic Automotive Electrical Troubleshooting

All automotive electrical circuits require a certain amount of voltage from a power source, a connection that completes the circuit and a condition of continuity. Broken, cracked or loose wires can disrupt a circuit or cause it to be incomplete. Wires that have aged or been used with very high amperage can break down and cause interior resistance, leading to lower than normal voltage readings. Basic automotive electrical troubleshooting requires some knowledge of the separate electrical systems and the use of some gauges.

Instructions

    1

    Check your battery's standing voltage by clipping the positive lead of a multimeter to the positive battery terminal. The cable ends must be free of corrosion for this test. Clean them with a wire brush. Clip the multimeter negative lead to the negative battery terminal.

    2

    Set the dial for volts. You should read at least 12.6 volts. If it reads less, you must charge the battery and take another reading. If the battery remains below 12.6 volts, or has a reduction of more than two volts, you must check the cells.

    3

    Remove the sealed or pop-out battery cell caps and check each cell with a battery hydrometer. The cork or plastic floats in the hydrometer should float in the "Green" section, with no cell appearing in the "Yellow" or "Red" margins. Yellow or red readings indicate a defective cell, which means the battery must be replaced.

    4

    Check the charging system by placing the positive lead of a multimeter to the positive terminal of the battery. Place the multimeter negative lead on the negative battery terminal. Start the engine and read the charging system voltage output. The charging system voltage should read between 1.5 and 2.0 volts over the battery standing voltage, or 14.1 to 14.6 volts. If it does not, a problem lies with the alternator, alternator belt or regulator.

    5

    Turn the engine off. Connect a clip-on amp meter to the positive starter cable. Set the amp meter for the 1,000 amp scale. Disconnect the ignition coil wire from the coil or coil pack. Ground the coil wire to the engine block with a piece of coat hanger wire. Have assistant apply the emergency brake and place his foot on the brake pedal. Have him attempt to start the vehicle in neutral and let the engine crank for several seconds.

    6

    Look at the starter amperage draw reading on the amp meter . Refer to your owner's manual for the maximum amount of amperage draw allowed for your vehicle. Anything over 200 amps will be suspect, indicating resistance in the starter winding. Check your external solenoid by placing a jumper wire onto the starter battery terminal on the solenoid and the other end of the wire onto the hot sender wire. If the solenoid does not engage to spin the starter, the solenoid contacts have failed.

    7

    Check your lighting components by first removing the lens caps with a screwdriver and examining the bulbs. Replace any bulbs that have broken carbon filaments. Check the socket connection for corrosion and the bulb socket ground wire. Headlights, turn signals, brake lights, plate and backup lights can be checked in this fashion. If the bulbs show good filaments, go to your main fuse box panel and check the appropriate fuse for each lighting component.

    8

    Look at the filaments in the spade or tube-type fuses. Replace any that appear burned or disconnected. Check the main headlight relay if both headlights fail to operate. Switch the suspect relay with another known good relay and see if they work. If they work, replace the bad relay with a new relay. If the fuses, relays and bulbs appear good but no illumination results, run a jumper wire from the positive terminal on the battery to the hot lead inside the bulb socket.

    9

    Turn the ignition key to the "On" position and make sure the bulb socket has a good ground connection. If the bulb lights with the jumper wire, it indicates a defective wire from the power source. Use a 12-volt test light to probe a suspect wire from its component source to its nearest connection to a battery power source.

    10

    Stab the wire with the sharpened test light probe and watch for the test light to illuminate. If it fails to light, the wire does not have voltage to it at that point. Look for any in-line fuse or fusible link further upstream toward the power source, and replace any that appears blown.

    11

    Disconnect the battery source or fuse to a component when you need to check the ohm resistance in a wire. Set a multimeter to the low ohm setting. Place the ohmmeter leads at opposite ends of the wire or on the opposing sides of a switch. Read the ohms. If you have a higher than normal ohms reading, it indicates resistance in the wire or switch or a corroded and partial ground. Clean all ground wires and straps, especially braided engine ground straps.

    12

    Refer to your owner's repair manual for the normal resistance allowed for the wire or switch on your vehicle. Keep in mind that the gauge (diameter) of wire when considering the maximum allowable ohms. Your owner's repair manual will have the wire gauge sizes and component voltage requirements, along with the amp and ohm threshold limits.

How to Tell If I Have a Bad Intake Manifold Gasket

Depending on the year, make and model of a vehicle, it may have a plastic, aluminum or cast-iron intake manifold. All manifolds use gaskets between the intake manifold and the head. In some cases, a vehicle has a two-part intake manifold -- upper and lower. In most of these cases, the lower intake is aluminum or cast-iron and the upper piece is plastic. When the manifold is two-part, it will have two gaskets, one between the lifter galley and the lower intake, and one between the lower intake and upper intake manifold.

Instructions

    1

    Note whether the vehicle has a rough idle. If all other components work properly and no other reason for the rough idle exists, the intake manifold gasket is suspect.

    2

    Start the engine. Listen for a vacuum leak. If none of the vacuum hoses leak, an faulty intake manifold gasket may be the cause. Spray carburetor cleaner around the gasket-mating surface of the intake manifold, both upper and lower, if you have a double manifold. If the noise stops, the manifold is cracked or warped, or the gasket is bad.

    3

    Look on the ground underneath the vehicle. If water puddles on the floor near the center of the engine on either side, and all other hoses are in good condition, the intake manifold gasket may need replacing.

    4

    Wipe any dirt, oil, grease or water from the area of the intake manifold gasket. Depending on how bad the gasket is broken, you may see nothing during idle except some steam, but you should be able to see water leaking from the gasket area if the gasket has a bad tear.

Jumat, 29 Oktober 2010

How to Test a 2007 Chevrolet 3500

The 2007 Chevrolet 3500 has a second-generation on-board diagnostic computer that monitors the power train and generates diagnostic trouble codes in the event of a malfunction. In order to troubleshoot a power train issue with your 2007 Chevrolet 3500, you'll need to retrieve these codes through a test of the system. Performing this test requires mechanical repair skill as well as a bit of computer savvy. If you possess both, you can test a 2007 Chevy 3500 in less than 20 minutes.

Instructions

    1

    Plug the scan tool's datalink cable into the 2007 Chevrolet 3500's diagnostic port located under the driver's side of the dashboard. For ease of visual recognition, the port is a female mate to the male end of your scan tool's datalink cable.

    2

    Turn the 3500's ignition to the run position. Perform a quick test on the 3500's on-board diagnostic computer per the specific instruction manual for your particular brand and model of scan tool.

    3

    Write the diagnostic code(s) down with pen and paper when they appear on the display screen of your scan tool. Complete the quick test without erasing the code(s), per the scan tool's specific instruction manual.

    4

    Turn off the 3500's ignition. Disconnect the datalink cable from the diagnostic port by hand.

Kamis, 28 Oktober 2010

Ford Focus Suspension Problems

Ford Focus Suspension Problems

Maintaining your Ford Focus' suspension system is important for all driving conditions, especially over rough roads. Proper suspension also offers you a smooth driving experience. Uncomfortable rides over normal roads is an indicator of suspension problems.

Struts

    Struts are the key components that help prevent the car from wanting to launch off of the road and then slam down during hilly or bumpy drives. As such, feeling your Focus bottoming is an indicator of worn struts. Other signs of worn struts include cupped tires and wheel noise and vibrations while driving.

Ball Joints

    Ball joints on your Focus connect the wheels to the car's suspension system. They allow the front wheels to move up and down over bumps and side to side when steering. Worn ball joints can cause cupped tires and noise in the front end of the car. A binding in the ball joints can seize the steering wheel from returning to a straight position after a turn.

Stabilizer Bar

    Your Focus' stabilizer bar prevents excessive body roll when cornering the car and stabilizes the car during rough driving conditions. As such, a loose stabilizer bar would cause poor steering stability, excessive rolling when cornering or turning and noise in the front end.

How to Troubleshoot a Slipping Transmission

When transmission problems surface in your vehicle, you should employ a few common troubleshooting techniques. Catching these problems early on can prevent more expensive issues from developing later. Familiarize yourself with the symptoms of transmission problems, and you'll be able to catch them should they arise again in the future.

Instructions

    1

    Look for leaks on the ground just beneath the engine. Transmission fluid is reddish, so it's easy to differentiate it from an oil leak. However, power steering fluid ca look similar to transmission fluid. A transmission fluid leak could mean a faulty pan gasket or filler tube, so try to look for the source of the leak.

    2

    Inspect the filler tube and check if there is fluid leaking out of it. Sometimes this could be the result of overfilling, or it could be a defective breather vent or a clogged filter.

    3

    Smell the transmission fluid. If it has a burnt odor, it could mean the transmission has overheated or the fluid is too low. Sometimes the burnt odor could be the result of a heavy load or a faulty oil pump.

    4

    Listen for a high-pitched whining or whirring noise while you're driving. This can be a sign of a clogged transmission filter or low fluid.

    5

    Notice if the gear shifting has been less than smooth. This could be sign of low transmission fluid, clogged filter or other transmission problems.

Rabu, 27 Oktober 2010

Can Heavy Rain Affect Your Car Battery?

Can Heavy Rain Affect Your Car Battery?

The humidity levels present during heavy rains may contribute to corrosion forming at the battery connections, but such conditions rarely affect battery function, or internal components. However, a car battery may seem to grow weaker as rainy day travels persist. The symptom could actually be a side effect of the operating conditions, rather than a direct response to the ample moisture. Traffic flow, electrical accessory operations and charging system function, must be taken into account to understand this clouded phenomena.

Speed Demons

    Heavy rains often cause traffic to slow to a crawl, even on interstate highways. Poor visibility and traction may force immediate, and possibly erroneous, driver reactions that impede forward progress. The engine revolutions needed for full charging system function are not achieved when inching along for extended periods. Although modern automotive charging systems are more capable than ever, no alternator produces maximum power at idle. Emergency vehicles are fitted with beefed-up alternators and engine speed controls to maintain good charging energy while powering all the elaborate lighting needed on such vehicles. Passenger vehicles lack this advantage and battery reserves are tapped heavily at low speeds.

Accessories to the Crime

    As the alternator struggles to keep energy flowing to the ignition system and fuel pump at low speeds, further battery reserves are stolen by the accessories used in inclement weather. The ventilation settings that clear the front glass employ electric blower motors to distribute the air, which in most cases is dried somewhat by the air conditioner. The rear glass might have an electric grid that dries the exterior and interior surfaces. The windshield wiper motor is also electric, while the headlights would be on in such instances. Other electrical equipment that could further rob the battery reserves can include fog lights, seat heaters, and repeated brake applications that illuminate a host of light bulbs to warn neighboring motorists.

Slip Sliding Away

    Just as car tires lose traction when wet, the same is true of the rubber belts that drive alternators. The squeal that normally accompanies belt slip may not occur when the pulleys and belts are wet. A slight imperfection in the belt drive system that escapes notice might have a minimal effect on sunny days, but cooling and lubricating water can aggravate the situation. Increased loads on the alternator make it harder to turn over and it is possible for the belt to glide silently through the alternator pulley when good traction is most acutely required.

Back to the Weather

    Colder temperatures that can coincide with rainy days might be blamed for some battery weakness, as cold does affect the specific gravity of the electrolyte contained in the battery case. Poorly sealed engine compartments could allow water to collect on the top of the battery and form a wet short circuit across the battery posts. A slight power drain occurs in this instance and will continue as long as the water remains in place. Side-post batteries are not subject to such ills; however, both top and side-post designs can be fouled by corrosion. Cables and connections that are kept clean and dry work best, and these considerations have lead to alternative battery placements. The battery is mounted under the rear seat bench, in some car models, and this particular design has gained in popularity recently because of its success in keeping the battery out of the elements.

How to Troubleshoot Hesitation in a 1999 GMC Sierra Truck

How to Troubleshoot Hesitation in a 1999 GMC Sierra Truck

A 1999 GMC Sierra truck has an onboard diagnostic (OBD) computer that will detect and diagnose problems with your truck. Hesitation in the engine can be caused by a failure in a number of systems, and the OBD will turn on the check engine light when necessary to let you know if the truck has a problem. A simple computer diagnosis will give you a code that can be downloaded and matched to the troubleshooting codes in your owner's manual to find out what the specific problem is with your Sierra.

Instructions

    1

    Locate and remove the cover from the fuse box on your 1999 GMC Sierra. Find the multiple-pin OBD computer port for your vehicle in the fuse box. Plug the diagnostic scanning tool into the port and turn the key to the right but do not start the engine.

    2

    Turn on the diagnostic tool, per the manufacturer's directions, and wait for it to download the trouble code. The tool will usually say "OK" or something equivalent when the code has been properly downloaded.

    3

    Unplug the tool from the port and replace the fuse box cover. Scroll down on the menu on the diagnostic tool to where it says "retrieve code." Find the code or codes stored in the computer that are the source of the engine hesitation problem.

    4

    Match these downloaded codes to the troubleshooting codes in your GMC Sierra owner's manual to determine what problems the computer has diagnosed. Repair or replace these parts as needed.

Troubleshooting BMW 3-Series Engine Problems

Troubleshooting BMW 3-Series Engine Problems

While a BMW 3-Series' engine problems can be investigated by sight and sound, the car's second generation On-Board Diagnostic system can save you a lot of time. The BMW 3-Series features an internal computer called a Powertrain Control Module. The PCM runs a series of diagnostic checks and procedures, and every instance of a malfunction is coded and recorded. By accessing the PCM, you can get a list of things that have gone wrong in your BMW's engine. To do this, however, you will need an OBD-II diagnostic scanner.

Instructions

    1

    Open the BMW's driver's door. Crouch down, and look into the leg space. On the left-hand side, near the left-side kick panel, you will find a computer outlet. In older 3-Series vehicles, this outlet will be concealed behind a panel, which will be easy to remove.

    2

    Connect your OBD-II scanner to this computer outlet. Scanners will either come with a diagnostic cable that will fit the outlet, or the scanner itself will directly fit into this outlet.

    3

    Climb into the driver's seat and set the OBD-II scanner onto your lap. Place your ignition key into the BMW and switch to the "On" position. Some OBD-II devices may also need you to crank and run the engine.

    4

    Wait a few seconds for your device to retrieve codes from the BMW's PCM. You may be using a scanner that is not set for automatic code retrieval. In that case, consult your device's manual for the precise procedure and key in the command yourself. Button layout differs by brand of OBD-II scanner, and so the instructions will not be the same for all devices.

    5

    Read through the alpha-numeric codes on your device's display. Ignore everything do not start with "P," since you are looking for potential engine issues. The "P" stands for "powertrain," and those codes cover malfunctions in the engine and the fueling system. Copy the codes onto a separate piece of paper, if your OBD-II scanner was not manufactured with USB-to-PC connectivity.

    6

    Find the meaning for each P-code you have written down. Your scanner's manual should have definitions for all the generic universal to OBD-II compliant vehicles. If you own a lower end, generalized code reader, your manual may only cover general device operations. OBD-II coding definitions are easily found online. Also, you will need to locate BMW's special set of diagnostic codes online. Your BMW's manual will neither have these codes nor the generic ones. Make a list of all the potential problems that will need to be investigated.

    7

    Make a decision, based on the definitions you found in Step 6. You can either drive the car to a mechanic for repairs or attempt a DIY fix yourself. If you decide to continue to troubleshoot the problems yourself, open the BMW's hood. Investigate not only the problem central to each specific OBD-II trouble code, but the system surrounding it. For example, P0400 deals with "flow malfunctions" withing Exhaust Gas Recirculation system. Troubleshoot not only the EGR valve, but the EGR system as a whole.

Selasa, 26 Oktober 2010

How to Tell If a Coil Pack Is Bad?

How to Tell If a Coil Pack Is Bad?

The coil pack is an essential component of a vehicle. Its main purpose is to transform the battery's voltage to the required amount of volts needed to fire the spark plugs. The coil pack consists of thin coils that are wrapped around a central core hundreds of times. Coil packs can become defective sometimes. When this happens, early signs usually appear, such as decreased engine power, rough idle or engine noise. Along with these symptoms, you can use certain techniques to determine if the coil pack in your vehicle is bad.

Instructions

    1

    Open the hood of the vehicle and remove the electrical connector from the coil pack. This is located next to the engine oil dipstick in the engine compartment.

    2

    Connect a spark tester or a 12-volt test light to the battery's positive terminal. Place the test light probe for the test light on each of the outside terminals of the coil pack connector.

    3

    Stand at a safe distance from the vehicle and ask someone to start the car for you. As the car cranks up, check to see if the test light blinks. If the test light does not blink or there is no spark, that means that the coil pack is bad.

Senin, 25 Oktober 2010

Tips to Stop an Automatic Transmission From Slipping

Tips to Stop an Automatic Transmission From Slipping

Slipping occurs when you are accelerating and your engine is producing the power to go faster, but your vehicle does not shift promptly. The RPM gauge on your vehicle will read unusually high, but your vehicle may feel as if it is struggling to accelerate or is stuck at one speed for a moment, before the vehicle shifts. When an automatic transmission begins slipping, it is normally a sign of a problem within the transmission. There are several things you can do that may help if your vehicle's transmission has started slipping.

Error Codes

    The transmission control module stores error codes for your transmission just as the vehicle's computer stores engine error codes. If your transmission is slipping, it is a good idea to take your vehicle to a transmission shop and have these codes scanned in order to determine what exact problem is causing the transmission to slip and have it repaired.

Transmission Fluids

    A transmission that is low on fluid may slip or fail to shift promptly. Transmission fluid provides lubrication and hydraulic pressure for the transmission, so if the fluid is low or too old, you may experience shifting problems. Old transmission fluid is an issue because it does not provide the same amount of lubrication as new fluid.

    To prevent slipping and other shifting problems, you should service your transmission and change the fluid in accordance with the manufacturer's recommendations for your specific car or truck.

Transmission Additives

    There are a number of transmission additives on the market that claim to be able to prevent and stop transmission slipping and other related problems. These products may be able to prolong the life of your transmission or provide a quick fix for problems. However, you should discuss use of any specific products with your transmission specialist before you add them to your vehicle's transmission fluid.

Jeep Liberty Troubleshooting

Jeep Liberty Troubleshooting

The Jeep Liberty is the offspring of the Jeep Cherokee, one of the first sports utility vehicles. The Liberty comes standard with a 3.7-liter, 210-horsepower V-6. Owners have the option of two- or four-wheel drive. As Edmunds points out, the Jeep Liberty was designed for off-road traveling. When something goes wrong with your Jeep Liberty, tracking down the source of the problem involves a logical process of elimination. Begin with the major sources of the engine's power, then narrow your search from there.

Instructions

    1

    Crank the engine and lift the hood. Check the hoses for cracks or damage, check the wires for looseness or disconnects, and check the belts for breaks or looseness. Look for signs of excessive wear, damage, rust and corrosion. Parts exhibiting these signs need to be examined and possibly replaced.

    2

    Pull the "Check Engine" codes. Attach the probe of an OBD scanner to the Assembly Line Diagnostic Link (ALDL) located under the dash on the driver's side. Follow the prompts on the scanner's screen and select the option to pull the diagnostic codes from the computer. Write them down and consult your owner's manual for what these codes mean.

    3

    Check the alternator and battery for sufficient energy with a voltmeter. Attach the positive, or red, voltmeter lead to the positive battery post and the negative voltmeter lead to the negative battery post while the engine is off. The voltmeter measures the voltage in the battery and should read between 12.5 and 12.8 volts. Crank the engine to test the alternator and read it again. It should now show between 13.6 and 14.3 volts.

    4

    Pull the fuses under the driver's side dash. Use a fuse puller to extract each fuse and inspect for breaks. Discard any broken fuses and replace them with new ones of the same amperage. The amperage is printed on the bottom of each fuse, and the fuses are color-coded as well to make identification easy.

    5

    Check the fluid levels if your Liberty has overheating issues. Low oil and coolant levels can cause the engine to lose its ability to cool itself. Make sure the radiator fan comes on when the engine is hot and check that the thermostat is opening by carefully touching the upper radiator hose. The hose will be hot if the thermostat is opening to release heat to the radiator.

Cadillac Code B2711

Cadillac Code B2711

Cadillacs and other General Motors vehicles that use the the Vehicle Anti-Theft System (VATS) may display a security error with the code B2711. This means that even though the car is probably starting just fine, the key's electronic chip is failing.

Significance

    The official on-board diagnostics description for code B2711 is "PASSKey Open/Shorted Pellet After Good Key." The ignition key can still start the engine, but the Cadillac's VATS has detected an electric failure with GM's proprietary PASSkey pellet. The pellet is the small chip embedded on the shaft of a Cadillac key, and the error code means it isn't connecting properly.

Solutions

    If your Cadillac key appears worn down, it's likely that the pellet is simply not making physical contact inside the ignition column. A GM dealer or other licensed VATS locksmith can provide a new key that will clear the error code. Otherwise, the damaged part may be inside the column and the ignition switch itself may need replacement.

DIY Alternative

    A B2711 code can also be cleared by bypassing the VATS system altogether. This means abandoning the Cadillac's anti-theft system and potentially voiding warranties. The bypass process involves using a voltmeter, soldering iron and wire strippers. Deciding to bypass VATS requires a certain amount of mechanical and electrical expertise.

Minggu, 24 Oktober 2010

Signs of a Bad Fuel Filter in a 1993 Ford Escort

The 1993 Ford Escort is a member of the second generation of this vehicle type manufactured from 1991-1996 by the Detroit based automaker. This generation featured new developments for Ford models including fuel injection, sports packages and trim levels. Fuel filters, an important part of the vehicle's engine system can cause problems for Escort owners if allowed to clog or otherwise malfunction.

Hesitation During Acceleration

    A clogged or damaged fuel filter in a 1993 Escort will cause the vehicle's 4-cylinder engine to hesitate while accelerating. This is because fuel cannot flow to the engine in adequate supply resulting in an altered air-to-fuel mixture. Drivers may notice the engine begin to sputter when first pressing the gas pedal. Acceleration will be choppy with drivers feeling the vehicle lurching to get back up to speed. The problem caused by the bad fuel filter may seem to go away once the vehicle is up to speed but it will quickly reemerge once the vehicle stops.

Loss of Power at High Speed

    The lean fuel mixture that results from a clogged fuel filter can cause an engine to lose power when running at high speeds. Vehicles with fuel injected engine systems like the Ford Escort are particularly sensitive to timing issues that can result from a bad fuel filter. As a result, drivers may also experience engine backfires resulting from too much air in the fuel lines and a decrease in fuel economy from improper combustion.

Rough Idle/No Start

    A rough idle is a common symptom of a bad fuel filter in a Ford Escort. This is due to inadequate engine combustion that creates fuel starved conditions in the vehicle's engine. Drivers will notice a rumble in the engine block that can result in the vehicle stalling out. A completely blocked fuel filter will more than likely result in the Escort not being able to start because no fuel can make it through the blockage to power the engine.

How to Troubleshoot a Chevy Lumina PCM

How to Troubleshoot a Chevy Lumina PCM

A Chevrolet Lumina's powertrain control module as at the heart of the vehicle's On-Board Diagnostic system. If it ceases to work, you will have to have it replaced immediately. The PCM monitor's engine and fuel system functions, and it keeps a record of everything that goes wrong. Once a fault is detected, the PCM activates the Lumina's check engine light. If your are driving a Lumina with a dead PCM, you will not get advanced warning of serious engine malfunction.

Instructions

    1

    Page through your OBD-II scanner's manual and bookmark the pages listing generic OBD-II codes universal to all vehicles made after 1996.

    2

    Print out Chevrolet's OBD-II codes off of the internet. These will be General Motor's supplemental trouble codes. The Lumina's manual will not have these codes. However, a Haynes or Chilton repair manual will, and you will find it the chapter dealing with emissions.

    3

    Read through the materials and highlight all the trouble codes dealing with the PCM. Code P1621, for example, deals with the PCM's memory and its perfomance. Place all the highlighted material into your Lumina's navigator seat.

    4

    Walk around the car and climb into the driver's seat. Connect your OBD-II scanner to the Lumina's diagnostic computer port. This data link connector can be found under the dash, above the gas pedal.

    5

    Turn the Lumina's electrical array on, and depending on your brand of scanner, possibly the engine too. Look at the scanner's display, and key in a retrieval code, if your brand of scanner was not prefigured to automatically do so. Since all scanners are manufactured slightly differently, consult the scanner's manual for precise instructions.

    6

    Scroll through the codes reported on your scanner's display. Look only for the PCM related codes you highlighted earlier. If there are no PCM related codes on the scanner's display, then the component is fine. Seriously consider, however, troubleshooting any unrelated, non-PCM codes reported by your scanner.

How to Check and Repair the Ignition Module on a 1990 Buick Le Sabre

The ignition control module on a 1990 Buick LeSabre is a full-function ignition control module. It receives an 18X and 3X sync signal from the crankshaft sensor to use for firing the coil in a specific sequence as well as timing for starting. In turn, the ICM sends a 3X signal to the power train control module, which determines timing strategy relative to real-time demand and returns the 3X signal to the ICM for ignition timing during engine operation. The ICM also sends the 18X crankshaft signal to the powertrain control module that controls the sequential fuel injection.

Instructions

    1

    Check for spark, assuming the check engine light is not on indicating a sensor problem. If the light is on, pull the codes to ensure the crankshaft sensor is working. This requires a code reader available at any auto parts store. Auto parts store personnel can also provide the meaning of the code. The crankshaft sensor is the trigger. Without that, the ICM will not function. Pull a spark plug wire off a spark plug on the radiator side of the engine. Insert a spark plug into the end of the wire and lay it on the engine in good contact with bare metal for a good ground. Have a helper crank the engine over while you watch the plug. If there is a spark, the ICM is working. If there is no spark, pull the spark plug and install the wire back on the spark plug on the engine.

    2

    Look at the coil pack -- three coils grouped together -- and find them on the radiator side valve-cover perched on top of the flat ICM. In front of the ICM, which faces the radiator, you'll find an electrical connector with fourteen wires with an 8 mm bolt in the center to secure the connector to the ICM. Connect the voltmeter black lead to a good ground. Use the red lead to probe the next to the last wire on the passenger side of the connector. Use the center bolt as the dividing line between the fourteen wires -- seven on each side of the bolt. When facing the connector from the front of the car, the next to the last wire closest to the fender well is the wire you need to probe.

    3

    Turn the key to the "On" position and the voltmeter should display 10 volts give or take a half a volt. If voltage is present, move to the next test. If no voltage is present, the ICM is bad.

    4

    Leave the ground lead where it is and probe the white wire, which is the first wire on the driver's side of the connector. Have the helper attempt to start the car. Watch the voltmeter. It should show 12 volts for a flash and then "0" and "12" and so on. This will happen quickly, so watch carefully for these fluctuations, which are called duty cycles. If the voltage does not fluctuate, the ICM is bad. If they do fluctuate, the coils are bad.

    5

    Disconnect the voltmeter and put it away. Disconnect the battery negative cable using a ratchet and socket. Mark all the plug wires in a 1-2-3 sequence starting at the top coil for reinstalling in the same manner once removed. Pull all the coil wires out of the coils.

    6

    Remove the 8 mm bolt in the center of the electrical plug in the front of the ICM. Pull the plug out. Remove the bolts from the bracket holding the ICM using a ratchet and a socket. Roll the ICM over and remove the bolts holding the ICM to the mounting bracket using a socket.

    7

    Remove all the bolts securing the three coils to the ICM. Lift each coil, one at a time, off the ICM carefully and disconnect the two wires under each of the coils to the ICM.

    8

    Install the coils in the same order on the new ICM. Do this one at a time, connecting the two wires to each coil. Set the coil down on top of the ICM and install the bolts securing this coil. Move on to the next coil until all three are mounted. Mount the coil on the support bracket and install the bolts.

    9

    Install the ICM to the valve cover and tighten the bolts. Install the ignition wires. Install the electrical connector taking care to ensure that you push the plug in straight so you do not bend the pins. Tighten the center bolt snugly to draw the plug in all the way. Do not over-tighten the center bolt.

How do I Diagnose Car Problems in a '92 Saturn?

The Saturn car brand enjoyed a large amount of popularity. However, General Motors starved its Saturn division of R & D funds. Additionally, the UAW refused to renegotiate wages and benefits to match the Asian competitors, so Saturn cars slowly got worse as lower-quality parts were used to keep costs down. The 1992 Saturns can have a number of minor and major issues that could be causing problems, due to the cost-cutting and low-quality parts.

Instructions

    1

    Inspect the tires for any damage or worn tread. The first thing Saturn started to cut back on was the tires (the lower-quality rubber would fray early). If the tires are worn bald then they must be replaced, as they will not have any grip on the road if it rains. Look to see if any of the tires is low on pressure, which might indicate an air leak.

    2

    Pop the hood of the Saturn and inspect the engine bay. If your car is a turbo model, then inspect the turbo housing for any deformation. If the blow-off valve had jammed shut, then overpressure could have distended or even ruptured the housing. Look on the downpipe to see if the blow-off valve is still attached. If the blow-off valve is missing, then the car will be down on power until it is replaced.

    3

    Turn the car on and shift into drive. Listen for the transmission to shift, any loud bangs could indicate a failing transmission. Listen for any grinding while driving straight if you have an all-wheel-drive Saturn. Grinding could indicate a warped transaxle or a damaged transfer case.

    4

    Listen to the car when steering around a corner. Any periodic clicking or banging could indicate a damaged steering knuckle or continuous velocity joint. The steering knuckle is what allows the wheel to twist independent of the axle and the continuous velocity joint aides in that endeavor. Have the car flat-bedded if the steering is compromised in any way.

    5

    Look at the interior panels to see if they are hanging off. Listen for them to squeak or rattle during your test-drive. To keep prices down Saturn used a lot of hard plastics that become brittle with age. These plastic panels can break their retaining clips and pegs and become loose.

Sabtu, 23 Oktober 2010

Pontiac G6 Electric Power Steering Problems

The Pontiac G6, a mid-size car available in coupe and sedan, was introduced in 2004 as a replacement to the Grand Am model. Despite being Pontiac's "go-to car" according to Edmunds.com, the G6 suffers from numerous mechanical issues. In particular, the G6 suffers multiple power steering problems which may result in an accident.

Power Steering

    Pontiac technical service bulletins (TSBs) indicate the the G6's main steering problem is the loss of power steering assistance. TSBs report that the primary cause of power steering loss is electrical input signal failure within the steering column.

Symptoms

    TSBs state that one indicator of power steering assistance loss is difficulty turning the wheel, which may require "increased steering effort." Additionally, the steering wheel may move slightly by itself. If the power steering unit fails completely, the steering wheel may become inoperative.

Solution

    Prior to deciding to replace the entire steering column, a professional should determine whether replacing the power steering pump or power steering hoses will remedy the problem. Pontiac TSBs indicate that the most common remedy for the G6's power steering failure is steering column replacement, which can cost anywhere from $600 to $1500 (as of March 2011).

How to Troubleshoot a Nissan Pickup Transmission

Nissan pickup transmissions manage the transfer of power produced by the engine to the driven wheels. Nissan makes both automatic and manual transmissions. Automatic transmissions change gears through the use of electric pumps and hydraulic fluid, shifting gear-sets at pre-set speeds without driver intervention. Manual transmissions use a manually operated clutch to disconnect the gear box from the engine so that shifts can be made. Troubleshooting both is necessary for the car to stay useful.

Instructions

Automatic Transmissions

    1

    Examine the floor of the garage or driveway where you park the vehicle. Transmission fluid looks like cherry cough syrup. Check to see if it's coming from the front of the transmission or the rear. There are two main seals in a transmission. One joins it to the engine. The other joins it to the drive shaft. Leaks can come from either one.

    2

    Open the hood when the engine is warm and smell inside. Burned transmission fluid makes a strong odor. Low fluid level, internal slippage caused by mechanical defects or clogged fuel lines can overcook the fluid.

    3

    Take the pickup for a drive and listen closely to the transmission. If you hear whirring or buzzing coming from the automatic transmission, there could be a defective torque converter or the fluid level might be low.

    4

    Pay attention to the shifting pattern and speeds of the pickup. Shifting should take place at the same engine speed and ground speed under the same driving conditions and go through all of the gears all the time. If the pickup starts shifting at much lower or higher speeds than usual or misses a gear, there is something wrong. This could be caused by a broken vacuum linkage control, broken lines, or band failure.

Manual Transmissions

    5

    Look for a sudden gear change into neutral. Does the pickup pop out of a gear? Is it the same gear? If it's the same gear, then it could be a transmission problem. If it's all gears, it might be a bad clutch.

    6

    Listen for strange noises when you shift. The synchronizers inside the transmission help match gear speeds so each gear is traveling at the same rate for the shift. They should make each shift quiet and smooth. If you hear grinding in any gear, then the pickup needs to be serviced.

    7

    Be aware of the effort it takes to move from gear to gear. The effort should be the same in all gears. A clutch problem can make it hard to move from gear to gear, but it will be the same for each gear change. When it's harder to move from fourth to fifth than it is to move from first to second, there's a problem developing inside the transmission.

    8

    Open the hood and check the engine mounts. Look for open breaks or cracks. If the engine shifts, it will move it out of alignment with the transmission.

    9

    Ask your mechanic to change the transmission fluid and look for metal shavings which may be in the fluid or clinging onto the drain plug.

Jumat, 22 Oktober 2010

How to Check Bearing Wear

How to Check Bearing Wear

In engines with rotating parts, bearings provide the mechanical glue that not only keeps the parts working correctly but also prevents them from failing catastrophically. When bearing wear occurs, various signs begin to become apparent to the trained eye. When aught in a timely manner, bearing replacement can save an engine from serious part failure and disintegration. Ignored, and the bearing itself can eventually come apart under high speed and pressure.

Instructions

    1

    Locate the particular engine part that you know has a bearing attached to it. Try to manipulate the part to see if there is any play or excessive wiggle. For example, test wheel bearings by grabbing the vehicle wheel with both hands and try to wiggle the tire -- you shouldn't be able to. Identify odd movement in bearing-connected parts for further inspection of the bearing involved.

    2

    Expose the bearing installed in the particular mechanical part by removing the bearing seals, if necessary. Use a bearing puller to remove the oil seal. Use a flashlight if viewing is difficult.

    3

    Look for signs of burning, scoring, carbon blackening or scratches. Replace the bearing if any such signs are found near or on the bearing in question. Install new bearing seals as well, throwing out the old ones once removed. Place the new bearing with a properly-sized drift and hammer. Install a new bearing by tapping it into place with the same tools.

    4

    Examine the grease around the installed engine or part bearing for contamination or drying out. Look for bits of metal or dirt in the grease to identify degradation of the bearing parts. Wipe off the old grease and compress new engine grease into the bearings to provide adequate lubrication.

    5

    Look for brown or blue shades of coloring on the bearing itself, signaling excessive heat damage from too much friction in the bearing parts. Replace the bearing if found as friction has probably already caused damage which will only get worse with time.

    6

    Use new bearings from a reputable provider. Do not use cheap bearings simply based on price alone. Confirm the bearing can handle the application you put it into by checking the bearing grade score if any on the packaging. Compare the grade score with the requirements of your engine or part using the bearing before installation.

Kamis, 21 Oktober 2010

How to Test a Pickup Coil on an ATV

An ignition system uses several capacitors, sensors and coils to send electrical energy from the source -- alternator or battery -- to the spark plug. The pickup coil, also known as the stator, provides a low-voltage on/off signal to the ignition module, which interprets the signal's frequency as an indicator of rpm. Pickup coils aren't generally expensive to replace, but a bad one can still strand you in the middle of nowhere.

Instructions

    1

    Locate the wiring harness on your distributor and unplug it. Different manufacturers use different systems, but in general the source (inside) coil's wires are solid-colored and the outside pickup coil's wires are multicolored. For example, the primary coil's wire may be red and white, while the pickup coils wires might be white/brown and white/green.

    2

    Set your multi-meter to the 2000-range Ohms, often abbreviated as "2K" followed by the Greek Omega symbol. Stick the end of the probes into the multi-colored wire terminals (on the engine side) and check the resistance. Manufacturer specs vary, but your reading should come in at somewhere between 270 and 350 Ohms; anything outside of this range indicates a bad pickup coil, as does an "infinite" reading.

    3

    Repeat this procedure with the solid wires to check the source coil; it's resistance should read about 200 ohms higher than the pickup coil, or from 450 to 570 ohms. Again, manufacturer tolerances vary, but if your meter reads 150 or 15,000 ohms, then you can be pretty sure that there's something wrong with the source coil.

Rabu, 20 Oktober 2010

Reasons a Power Steering Pump Leaks

Reasons a Power Steering Pump Leaks

The power steering pump is an automobile device that provides hydraulic pressure to assist with steering. Though power steering pumps will typically provide for many years of dependable use, leaks can develop that may cause the system to fail.

Seal Leaks

    As the seals in the power steering pump and system age, the seals may shrink and become brittle, allowing power steering fluid to leak. Leaks in the seals are the most common source of a power steering leak. Power steering stop-leak additives can be used to restore older seals, but seals that have broken will require replacement.

Line or Hose Leaks

    Power steering lines and hoses transfer pressurized power steering fluid from the power steering pump to the steering rack, small cracks and tears can develop in these lines, creating a leak. Power steering fluid leaks from lines and hoses will require the defective part to be replaced.

Pump Housing Leaks

    The power steering pump typically has a fluid reservoir built into the housing, though some are separate. This housing can become cracked and cause a leak, which will require replacement. The power steering's bearings and internal workings may also become worn, allowing fluid to leak and requiring the pump to be replaced.

Selasa, 19 Oktober 2010

How to Tell What Direction a Car Engine Turns

How to Tell What Direction a Car Engine Turns

Engine, or crankshaft rotation, is the direction the engine spins: either clockwise or counterclockwise. Most vehicles have the standard rotation, counterclockwise. Only a few vehicles, such as early Hondas and the American-made Chevrolet Corvair flat-six, had reverse rotation, or right-hand spin in a clockwise direction. If you want to determine the turning direction of an engine, there are a few things to look for.

Instructions

    1

    Look up your vehicle engine size and statistics in an owner's repair manual for the exact make, year, and model of your vehicle. Engine rotation -- either standard or reverse -- will be listed under engine statistics and performance. Chances are good that your engine is standard and rotates counterclockwise.

    2

    Raise the hood of the vehicle and disconnect the ignition coil wire from the coil or coil pack. Put the transmission selector in neutral or park, depending upon your transmission type. Set the emergency brake.

    3

    Raise the vehicle with a floor jack and place two jack stands under the rear frame and two jack stands under the front frame.

    4

    Use a socket and ratchet wrench to remove the inspection cover of the flywheel. Use a screwdriver if screws hold the plate to the housing. Check your owner's manual to see if your inspection plate sits on the top or the side of the engine (unique to your make, model and engine placement) and remove it with a socket or screwdriver.

    5

    Instruct an assistant to "bump" the starter over, to rotate the engine. Watch the rotation of the flywheel from the rear. If the flywheel turns counterclockwise, or left-handed, it denotes a standard rotation. If the flywheel turns clockwise, or right-handed, it signifies a reverse rotation engine. Remember that if the front of the flywheel shows through an inspection plate, reverse the rotation to account for the flywheel as seen from the rear.

    6

    Stand in front of the engine, facing the pulleys. This applies to an inline or side-mount engine. Have an assistant bump the starter motor so the pulleys and belts move from the crankshaft rotation. This procedures works if you cannot see the rear or front of the flywheel anywhere on the engine. Note the rotation. Pulleys that move clockwise have left-hand rotation, and pulleys that turn counterclockwise have right-hand rotation.

What Causes a Squeaky Noise From the Front of a Vehicle at Lower Speeds?

Squeaking cars leave you three basic options: You can fix the squeak; you can sell the car; or you can begin plotting to take over the world with a legion of trained mice under the hood. Since the last two aren't options for most, the logical choice is to track the squeak down and get rid of it. First, you need to know where to look.

Ball Joints

    Your car's upper and lower ball joints -- the spherical links that connect the steering knuckle to the control arms -- are a likely culprit, especially if the squeaks occur even when bouncing the car body while parked. Suspect a bad ball joint if the car emits more noise when you bounce the body on one side than it does on the other side. A dry ball joint emits more of a screech than a squeak -- the sound of metal grinding against metal rather than rubber chattering against rubber or metal. Many cars have smaller ball joints on the steering end links that warrant equal consideration.

Bushings

    A bushing is a rubber isolator that sits between a suspension bolt and the chassis, like a sleeve that goes around the bolt and keeps minor vibrations isolated in the suspension. These rubber, sometimes plastic, isolators consist of a flexible inner core with a metal sleeve on the inside and possibly the outside. This rubber shrinks and dries as it ages, and the metal sleeves themselves wear and allow for some slop in the assembly. Any bushing, if its worn or old enough, causes suspension squeaking at low speeds and when going over bumps.

Spring Isolators

    A spring isolator is a rubber puck or gasket that sits between the top of the coil spring and the chassis. The isolator keeps the spring from chafing against the chassis metal, and works something like a bushing to keep suspension vibrations out of the chassis. These isolators can wear through and allow the spring to come in contact with the chassis, or they can shrink and dry out. Once the isolator rips or starts to move around, it'll squeak against the spring mounts, especially when traversing a washboard road or any kind of quick bump.

Worn Chassis

    While uni-body or frame-less chassis may be light and cheap to produce, they do have one inherent flaw. A uni-body essentially is a bunch of steel panels stitch-welded together; over time, excess shock loading (read: jumping your car like them Duke boys and hitting every pothole at 80 mph) will work harden the welds and break them like bending a paperclip back and forth. Once the welds weaken, your chassis starts flopping around like a wet noodle and hard components such as the doors and trunk lid rub against the weatherstripping. Short of stripping the car down to its shell and re-welding everything, a set of front and rear triangulating strut tower braces will help restore some of the lost chassis rigidity.

Prevention

    Much of preventing chassis squeaks and chassis wear in general comes down to proper maintenance and periodic lubrication. Big tractor trailers experience far greater stresses than the average automobile, but even the average one has a service life of several million miles. But trucks are machines of commerce, which means they're designed with regular greasing and lubrication in mind. Your car may not have suspension components that can be lubricated, such as steering components and bushings, but that doesn't mean you can't hit them with a spray of penetrating oil or spray-grease during each oil change. It's 15 minutes well spent.

Senin, 18 Oktober 2010

How to Troubleshoot Turn Signals

How to Troubleshoot Turn Signals

If your turn signals stopped working, there's no need to panic or run straight to an auto mechanic. Turn signals are one of the features on cars that you can expect to go out at some point, so you should know what to do when this happens. You can do some troubleshooting yourself to diagnose the problem, because it may be an easy and inexpensive fix. You will need to check a few components, in order, with the help of a few standard tools.

Instructions

    1

    Check for a blown turn signal fuse. Locate the fuse box, which is usually underneath the dash board, and remove the cover with your hands or with the help of a flat head screwdriver. Refer to your owners manual to see which fuses are connected to your turn signals and remove them with a pair of pliers. If the metal link in the fuse is separated, it is blown and you will need to install a replacement.

    2

    Remove the turn signal bulbs (if the fuses don't appear to be blown) by pushing them in and turning them counter-clockwise. If the bulb has a dark film around the base, it is burned and needs to be replaced. If the bulb looks OK, clean out the fixture and the base of the bulb with a rag to get rid of any dirt that may be interfering with the connection. Check the turn signal and to see if it is working.

    3

    Check the wire connections to the turn signal bulb sockets and the grounds, which are often connected to the fender (the side of the car). If the connections are rusty or corroded, make sure the power is off to your car and unscrew them. Buy a new ground wire and attach it by screwing it into place.

What Are the Dangers of Driving With a Tire Bubble?

What Are the Dangers of Driving With a Tire Bubble?

Tires can fail in any number of ways, some more predictable than others. Generally speaking, tire failure is the result of either wear or damage during the course of duty, but sometimes it can result from an error at the tire assembly plant. Driving on a tire bubble is just like driving on a balloon; sooner or later, it's going to pop.

Tire Basics

    Tires are not made of a single piece of rubber; rather, they're composed of several plies or sheets bonded together with adhesive. Under normal conditions, these plies stay glued together for the life of the tires and act to reinforce each other. However, ply separation will allow tire pressure to push out on the thin outer layer, creating a bubble.

Defect Bubbles

    Believe it or not, a certain amount of ply separation isn't uncommon, particularly with new tires. The glues used to bond tires are very sensitive to environmental conditions and contaminants; that's what that six-month to one-year "manufacturer defect" warranty is about. The initial bubble may be very small, but vibration and movement will eventually cause the bubble to grow. Sooner or later the bubble will grow large enough to create vibration.

Damage Bubbles

    Defect bubbles will typically appear within six months of a tire's installation on the car. After that, a bubble is likely the result of damage to the tire. Hitting large potholes or curbs will place a shear stress on the tire, causing the outer ply to to separate from the inner ply. Under-inflated tires and tires with very short sidewalls are more prone to impact damage than larger and properly inflated tires. Big, heavy wheels will also increase the odds of impact damage because the wheel's mass hammers on the tire during an impact.

Consequences

    The bubble is going to burst sooner or later, and when it does there's a good chance you'll experience a complete blowout. Blown bubbles can happen at any time, but are most likely to do so at high speeds when the tire is hot and moving very quickly. Use your imagination as to what will happen during to your car during a high-speed blowout. A rear-wheel blowout may prove catchable, but a front tire blowout will almost certainly result in rapid veering and probable loss of control. Bubble-induced vibration will also quickly wear out shock absorbers, springs and control arm bushings. Wheel bearings aren't particularly fond of constant vibration, either.

Minggu, 17 Oktober 2010

Engine Troubleshooting Guides for 2002 KIA Optima

Basic engine troubleshooting procedures for the 2002 Kia Optima are given in the Owner's Manual that is included with the car at point of sale. Detailed troubleshooting procedures for all systems, including the engine, are provided in the various Kia Motors technical information manuals, all of which can be found on Kia Motors Global Information System Internet site.

Troubleshooting Known Problems

    The 2002 Kia Optima shop manual has a troubleshooting section for both electrical and mechanical engine problems. Each section has a table of problem symptoms, likely causes, and recommended fixes. The root cause of most apparent engine problems can be determined by following the analysis procedures outlined in these tables. These procedures are most useful for engine problems that do not lend themselves to diagnosis by the car's On-Board Diagnostics system.

Regular Troubleshooting Procedures

    The owner's manual and shop manual for the Kia Optima specify certain troubleshooting procedures to be performed at specified regular intervals, These procedures are designed to reveal developing malfunctions that are not necessarily obvious while driving the vehicle, and aid in identifying potential issues before they develop into serious problems.

Computer-based On-Board Diagnostics

    Kia Optima models are equipped with second-generation On-Board Diagnostics (OBD-II) systems that greatly simplify troubleshooting. The OBD-II consists of a computerized system connected to sensors located throughout critical vehicle systems. The computer continuously monitors important engine functions and systematically analyzes the data to deduce vehicle problems. The OBD-II system transmits a specific trouble code that can be read by an OBD-II code reader once it senses a problem, and triggers a dashboard warning light to alert the driver if the problem requires immediate attention. The Kia Optima shop manual has a complete list of OBD-II codes and the engine problems that they signify. OBD-II readers are available at most auto parts stores, or you can have the codes checked by your mechanic.

How to Adjust the Idle on a 1986 Honda Civic

Honda's third-generation Civic from 1983 to 1987 used four engine variations on the E-series four-cylinder in the United States, and three more engines in Japan. Most Civics came with the EV1, a three-barrel carburetor version of the E-series producing between 60 and 80 horsepower. Later EW3, EW4 and EW5 engines received fuel injection, upping horsepower to between 91 and 100 horsepower. Setting the idle is an easy adjustment, requiring only the simplest of hand tools.

Instructions

    1

    Drive the 1986 Honda Civic on a flat surface and place it in park. Engage the parking brake before continuing.

    2

    Pop the hood to locate the carburetor's idle-adjustment screw. Follow the throttle cable coming from the firewall to the throttle bracket on the carburetor. Find the idle-adjustment screw on the carburetor's base plate. Grasp the throttle bracket and turn it to open the throttle plates and rev up the engine. When the bracket returns to its starting position, the flat spot on it comes to rest against a threaded tip -- this is the idle-adjustment screw.

    3

    Turn the screw clockwise to increase idle, or counter-clockwise to decrease the idle. On some fuel-injected engines, you'll find the idle-adjustment screw inside a recess in the top of the throttle body. The throttle body is the large valve that bolts to the intake manifolds where the carburetor otherwise would. Look down into the drilled recess for a black, flat-head screw; turn it clockwise to increase idle, counter-clockwise to decrease it.

    4

    Adjust the idle via the throttle cable. This is an alternative procedure for some engines, and the only available procedure for others. To adjust the cable, loosen one or both retaining nuts on either side of the cable where it passes through the throttle cable bracket. Now, readjust the nuts so that the cable either pulls the throttle lever open further or allows it to stay shut. Once you have the idle where you want it, tighten the nuts against the bracket.

Sabtu, 16 Oktober 2010

How do I Get Troubleshooting Codes for a 1994 Dodge Caravan?

How do I Get Troubleshooting Codes for a 1994 Dodge Caravan?

When the "Check Engine" or maintenance lights come on in your vehicle's dash, you know you've got problems. The computer stores trouble codes when they occur and sends an indicator to the dash panel to let you know what's going on. Retrieving those codes, and finding out what they mean, helps you track down the source of the malfunction. Pulling codes for a 1994 Dodge Caravan is simple. Dodge is a Chrysler product, so these methods work for all older Chrysler vehicles.

Instructions

    1

    Locate the "Check Engine" light on your dash panel, as this is where the troubleshooting codes come from.

    2

    Turn the ignition key into the "On" position without cranking the engine. Turn the key on and off in quick sequence (on, off, on, off, on), ending with the key on. Don't crank the engine. If you accidentally do, begin the sequence again.

    3

    Jot down the number of times the "Check Engine" light flashes. It will pulse several times to indicate the first digit of the code, then pause and flash again, this time to indicate the second digit. For example, Code 23 will flash this way: flash, flash, pause, flash, flash, flash.

    4

    Check under the dash for the Assembly Line Diagnostic Link, a 12-port electrical terminal. Turn the key into the "On" position, then connect ports "A" and "B." Click the link in "References" for a diagram of the ALDL. This runs the diagnostic sequence as well, with the error codes flashing from the "Check Engine" light.

How to Test Cam Sensors With an Ohm Meter

If your car begins sputtering or refusing to start, the problem could lie with a faulty camshaft sensor. Camshafts are connected to your engine's crankshaft and cause the valves to compress. According to Merced College, the camshaft sensor relays information to the fuel injector computer and times the spark that ignites the fuel-air mixture. A faulty cam sensor could disrupt the timing of your engine's stroke cycle. Testing its electrical resistance with an ohmmeter or multimeter allows you to troubleshoot the cam sensor. Cam sensor resistances and the location of the sensor vary with your vehicle's make and model.

Instructions

    1

    Move your vehicle to a well-lit area. Turn it off and wait several hours for the engine to cool off. For safety purposes, disconnect your car's positive and negative battery terminals by unscrewing the nuts near them with the 1/2 inch wrench and removing the terminals from the posts. Avoid allowing them to contact anything metal.

    2

    Consult your owner's manual to determine the location of your camshafts and sensors. Access them; you may need to remove other engine components in the process.

    3

    Connect the red lead of your meter to the socket marked "VO+." Connect the black lead to the socket marked "COM." Set your meter to the ohms setting if necessary. According to Harvard University, the symbol for ohms is the Greek letter "omega," which resembles a horseshoe.

    4

    Touch the leads of your ohmmeter or multimeter to opposite sides of the camshaft sensor on electrical contact points.

    5

    Note the measurement and consult your user manual to determine whether your camshaft sensor has the proper resistance.

How to Locate the Intake Manifold on a PT Cruiser

How to Locate the Intake Manifold on a PT Cruiser

The Chrysler PT Cruiser has been in production since 2001. The PT Cruiser has seen many upgrades since 2001, with the introduction of the PT Bruiser and the PT Cruiser Turbo. The 2011 PT Cruiser will feature a PT Cruiser Classic model and a PT Cruiser Couture model. Finding the intake plenum on the PT Cruiser is an identical process regardless of the year of the car, as the engine size and layout have not changed since 2001.

Instructions

    1

    Open the hood of your PT Cruiser.

    2

    Locate the air intake tube, which is the black tube that extends from the air filter box to the engine. Follow the tube until you get to the engine.

    3

    Look where the air intake tube enters the engine. The point at which it ends at the side of the engine is called the throttle body. The part on the other side of the throttle body is called the intake manifold. The intake manifold is seated directly on top of the main intake plenum.

Jumat, 15 Oktober 2010

GMC Sierra Transmission Problems

The GMC Sierra is one vehicle on General Motors' line of pick-up trucks. In 2011, the truck came in three models: the 1500, Hybrid and Denali. Throughout its years of production, the Sierra has seen several transmission complaints and problems.

Identification

    Consumer protection and feedback sites have identified complications with a number of Sierra year-models. These include but are not limited to the 1999, 2001 and 2005 models. However, it is the 2005 Sierra that saw official recalls due to the transmission.

2005

    Some 2005 Sierra 1500s were recalled due to issues with the gear box and shaft sector. The bolt connecting the shaft to the gear was found to be problematic. Additionally, some 2005 automatic transmission Sierras were recalled because various components of the transmission, such as the shift lever, did not meet safety standards issued by the Federal Motor Carrier Safety Administration. The shift pattern indicator on 2005 manual transmissions was also a subject to recall.

Considerations

    In some 2001 Sierras, the speed sensor did not operate correctly. Also, 2001 manual Sierras were found to have a parking brake problem if they were equipped with either the PBR or TRW system. 2011 Sierras are subject to recalls due to the locking of the rear axle. While the latter is not a transmission problem, it might be easy to misinterpret it as such.

Starting Problems in a Town & Country

A nonstarting Chrysler Town and Country may experience starting problems for a number of reasons. While there could be many different parts at fault, there are a few general areas to troubleshoot. Many of those smaller parts will be located in these areas.

Battery Trouble

    To start a Town and Country, the battery needs to have a charge. Even if the battery itself is fine, the battery's cables could be damaged or not properly attached. Older batteries also face corrosion problems. If the battery or its terminals show signs of white powder, then corrosion is present.

Fuel Issues

    If fuel cannot reach the Town and Country's injectors, then the vehicle will not start. Other issues can include a damaged fuel filter or faulty spark plugs. Water within the gas tank or any of the fuel lines will also immobilize the vehicle. Fuel systems can be complex, and the vehicle may need to be towed to a mechanic.

Wiring Concerns

    Any damage within the electrical system will cause starting trouble. While replacing blown fuses is a relatively easy remedy, the problem could also be with the automobile's relays. Check the wiring itself. Deterioration can lead to faulty wiring, and the electrical system will not work if wires are loose or not properly attached to their corresponding components. Wet wires can also temporarily disable a vehicle.

Mechanical Problems

    Investigate the Town and Country's starter motor. Any damage or malfunctions there could be to blame. Also, problems with the pinion may be at fault.

How to Retrieve an OBD2 Code Without a Scan Gauge

How to Retrieve an OBD2 Code Without a Scan Gauge

OBD2 trouble codes are part of a troubleshooting system that helps you track down the source of your engine's problems. For example, if the engine's computer recognizes a malfunction during operation, it isolates it, translates it into a code and saves it so you can access it. You retrieve it using one of the methods outlined here. Let's say the code indicates a too-rich oxygen-to-fuel ratio. Look this up in a repair manual and you'll see this is usually liked to a faulty oxygen sensor. Replacing it solves the problem and the code resets.

Instructions

Retrieve OBD2 Codes Using Your Ignition Key

    1

    Turn the ignition key "On" and "Off" without cranking the engine. How many times you do this depends on your particular vehicle. Most Chryslers require five times; other cars require three. End with the key in the "On" position. Start the sequence anew if you accidentally crank the car.

    2

    Watch the "Check Engine" or "Service" light on the dash. It will be lit, and will begin to pulse. Each pulse represents a number. A pause separates one digit from the next in a two-digit code. For instance, Code 23 will go like this: pulse, pulse, pause, pulse, pulse, pulse.

    3

    Write down the codes as they flash through the "Check Engine" light. Each code has a meaning, directly related to a problem in the engine. Look up the codes in a repair manual.

Other Options

    4

    Depress the odometer "Trip" and "Reset" buttons while turning the key "On." Release the buttons and watch the odometer display for the trouble codes to read out digitally.

    5

    Depress the odometer "Trip" and "Reset" buttons while simultaneously turning the ignition key "On" and "Off." End with the key in the "On" position. Release the odometer buttons and read the trouble codes from the digital odometer.

    6

    Locate the test port under the dash where the OBD2 scanner plugs in. Use a piece of jumper wire or even an unbent paper clip to link ports "A" and "B," initiating the diagnostic sequence. Watch the "Check Engine" light for the codes to flash.

Kamis, 14 Oktober 2010

Infinity I30 Troubleshooting

Infinity I30 Troubleshooting

Infiniti introduced the I30 car model in 1996. All I30's have an onboard diagnostic (OBD) computer installed. When the OBD detects a problem with your Infiniti I30, a "Check Engine" signal lights up on the dashboard to let you know a system is malfunctioning. A scan with an OBD auto diagnostic scanner will tell you what problems the car's computer has found in a system. The scanner downloads a code that is matched against the troubleshooting codes found in the owner's manual to diagnose the faulty system so it can be serviced, repaired or replaced as needed.

Instructions

    1

    Remove the cover from the Infiniti I30's fuse box located under the driver's side dashboard. Find the OBD computer port in the fuse box. It is a multiple-pin port that the auto diagnostic scanner plugs into. Plug the end of the scanner into the port and turn the key to the right but do not start the engine. The plug on the scanner should attach to the port easily. If it does not slide right in, back it out and start over. An OBD scanner for the Infiniti I30 is available at auto parts stores or online.

    2

    Turn on the diagnostic tool per the manufacturer's instructions and wait for the trouble code to download on the scanner. The scanner tells you when the code is read and downloaded.

    3

    Unplug the tool from the port by pulling it straight out and put the fuse box cover back in place. Scroll down on the menu on the diagnostic tool to where it says "Retrieve Code" and retrieve the trouble code stored in the scanner. The code indicates the problem with the car as diagnosed by the OBD computer.

    4

    Find the appropriate code listed in your Infiniti I30 owner's manual to determine what the problem is with your Infiniti. Repair and/or replace the faulty components on your vehicle as needed.

How to Check the Engine Code Without a Code Reader on a Dodge Stratus

How to Check the Engine Code Without a Code Reader on a Dodge Stratus

Back in the early 1980s, car manufacturers in the United States began to equip their vehicles with the on-board diagnostic system. In 1996, when the system was made mandatory, many manufacturers switched to the second-generation system, the OBD-II. Trouble codes stored in the computer of the first generation OBD system may be accessed through different methods, depending on the particular make and model. Chrysler continued to use the OBD-I system along with the second generation in many of its vehicles, including the Dodge Stratus.

Instructions

    1

    Place your transmission in park (automatic) or neutral (manual).

    2

    Start the engine and then race it up to 2500 rpm. Gradually, bring the engine speed down to idle again.

    3

    Turn on the air conditioner for about one minute---if your Stratus model is so-equipped---and then turn it off.

    4

    Depress the brake pedal if you have an automatic transmission, and move the shift selector through every gear and than back to park.

    5

    Turn off the engine and grab a small notepad and pencil.

    6

    Turn the ignition key to the on position and then to the off position. Repeat this step once more and then turn the ignition key to the on position again and let it stay there. You have now accessed your Stratus's computer trouble code memory.

    7

    Watch for the Check Engine light on the instrument panel to begin flashing.

    8

    Count the number of times the Check Engine light flashes before pausing and record the number, which will be a single-digit number.

    9

    Count the number of flashes in the second sequence, following the first pause. Place this single-digit number next to the first. For example, if the light flashes three times, pauses, and then flashes five more times, this will be recorded as 35.

    10

    Wait for a longer pause after the first two sequences of flashes and record the next two digits in the same manner as in the previous step. Each two-digit number is a trouble code stored in the computer memory. When the computer reaches the end of the trouble codes stored in memory, it will repeat the same codes so you may verify your notes. At the end of the second cycle of sequences, turn the key to the off position.

    11

    Look up the trouble code definitions obtained from the computer memory in the service manual for your specific Stratus model.

How to Find a Gear Oil Leak in a Ford F-150

How to Find a Gear Oil Leak in a Ford F-150

Ford F-150s use gear oil in the differentials to protect the ring and pinion gear sets from damage. Over time, the gaskets and seals can break down and fail to retain the gear oil, which could cause a leak around the rear cover, pinion seal or axle tube seals. This might require the efforts of an advanced automotive technician to repair the leak, depending on where it's coming from.

Instructions

    1

    Set the drain pan under the area where you have noted the leak on the F-150. Oil leaks leave a residue behind, so once you have gear oil on your differential or axle tubes, it's easy to spot.

    2

    Wash the leak residue off the F-150's differential or axle tubes with brake cleaner. Wipe the area clean and dry with rags.

    3

    Reposition the drain pan so it's directly below the differential fill spot. Remove the F-150's differential fill plug with a socket wrench.

    4

    Pour automotive leak dye into the differential and reinstall the fill plug. Clean any fluid that may have leaked from the fill plug, or any dye you may have spilled, from the side of the F-150's differential with brake cleaner and a rag.

    5

    Drive the F-150 approximately 20 miles. Shine the black light on the differential and/or axle tubes, concentrating on the area where you cleaned the residue from in step two. The leak dye will appear as a fluorescent green mark coming from the failed seal or gasket. Once you've spotted the dye, you've found the leak.

1995 Dodge Dakota Transmission Problems

1995 Dodge Dakota Transmission Problems

The 1995 Dodge Dakota came equipped with either an automatic or manual transmission. There have been no recalls or any major complaints from Dodge Dakota owners related to transmission problems found in the 1995 model-year. In fact, most transmission problems have been due to using DEXRON-II transmission fluid rather than the recommended MS-7176D, which provides more lubrication.

Transmission Fluid

    The most common 1995 Dodge Dakota transmission problem is with the automatic transmission fluid (ATF). This fluid lubricates the gears and cools the temperature inside the transmission. When the ATF is low, it can cause numerous problems, such as gear slippage between shifting, slow take-off or even lock-up. Under the hood of the 1995 Dodge Dakota is a dipstick to check the ATF level. The ATF level must be checked when the engine is idling and the parking brake in gear. If the ATF is too low, then add MS-7176D. Overfilling the ATF in the transmission can also cause transmission problems. A Dakota owner can easily determine whether the ATF needs to be changed by looking at the color of the ATF or smelling it. If the ATF is brown or very dark-colored, then the ATF may need to be changed; if the ATF smells burnt, then the transmission fluid needs to be changed as soon as possible.

Transmission Leak

    A reason for the ATF levels to go down in a 1995 Dodge Dakota is because of a leak in the transmission. This fluid leak may be coming from the seals inside the transmission. These seals can begin to deteriorate over time or when the truck is used extensively. The more daily miles put on a Dakota transmission, the harder the gears work, creating higher temperatures inside the transmission. This can cause the transmission seals to leak and lose fluid, requiring frequent addition of ATF or replacement of the seals by a qualified mechanic.

Transmission Filter

    The transmission in a 1995 Dodge Dakota has a filter that traps debris caused by normal gear wear. This filter can become clogged or cracked, causing the transmission to slip when shifting gears or slow take-off. The filter can easily be replaced by removing the drain pan to access the filter.

Computer Codes

    Once repairs or a fluid change is done on a 1995 Dodge Dakota, the check engine light will come on. If the check engine light comes on for no apparent reason, then the truck should be taken to a qualified technician and hooked up to a diagnostics computer. Chrysler transmissions may experience a bump shift problem which happens when the computer is not programmed properly to the shift points of the transmission. A technician can re-calibrate the transmission shift points to eliminate this problem.

Rabu, 13 Oktober 2010

How to Troubleshoot a Starter Solenoid in an Oldsmobile Cutlass Supreme

How to Troubleshoot a Starter Solenoid in an Oldsmobile Cutlass Supreme

When you turn the ignition key of your Oldsmobile Cutlass Supreme, there are a number of things that need to happen for the car to start. Should any one of them not happen, then your car is likely not going to start and the hunt to find the reason begins. In addition to the battery and starter motor there is another component called a starter solenoid. This is part of the electrical system that transfers the current from the battery to the starter motor. If it is defective, your Oldsmobile Cutlass Supreme will not start. Troubleshooting the solenoid is a fairly straightforward task.

Instructions

    1

    Remove the cable connections from your Oldsmobile Cutlass Supreme battery and from the solenoid. Clean the contacts using a toothbrush and a solution made of water and baking soda. Mix the solution at a one-to-one ratio.

    2

    Clean the cable contacts with the water/baking soda solution. Once the posts on the battery and solenoid are dry and the cable contacts are clean reconnect them and try to start the car. If the car does not start, move to the next step.

    3

    Test the solenoid by connecting a battery jumper cable to the battery post on the solenoid. Touch the second battery jumper cable to the other large post. If you hear no noise at all, the solenoid needs to be replaced.

How to Troubleshoot a Generator Alternator

How to Troubleshoot a Generator Alternator

The function of the automotive generator, or alternator, is recharging the battery after start-up and maintaining enough current for the engine components, accessories and sensors. Generators were used on older vehicles and did the same thing as the alternator, but were replaced because of their inefficiency to produce enough voltage at lower rpm. Alternators get their rotational force from a pulley and belt driven by the engine. They produce electricity through a series of copper wiring windings and an armature. Any failure of the interior alternator wiring, a mechanical shaft or bearing malfunction, or a missing fan belt can interrupt the needed flow of electricity. A competent vehicle owner can diagnose failing alternators with a few tools and tips.

Instructions

    1

    Place the vehicle in park or neutral with the emergency brake set. Open the hood. Attach a battery charger to your battery--red to red and black to black. Charge the battery fully. Inspect the inside and outsides of the battery cable connectors. Clean them with a battery cleaner tool, removing all oxidation, rust and dirt.

    2

    Turn the ignition key to the "On" position (not start) and note the dash lights that have illuminated. Start the vehicle and see if any of the lights have remained on. If a light that stays on reads "Bat" or "Alt," you have a low charging condition or a no charging condition in the alternator wiring circuit. If applicable, rent or obtain a trouble code scanner and trouble code book for your vehicle, then follow the directions for hook-up and analysis. This will pinpoint the charging problem.

    3

    Turn the ignition key off and step up to the engine compartment. Locate your alternator; use your owner's manual if unsure of its location. The majority of alternators sit directly under the power steering pump, and a single belt or a serpentine belt is around its pulley. Use a bright shop light to inspect the belt condition. Look for excess slack in the belt--if you can move the alternator pulley by hand, the belt has loosened up. Look and feel for cracks in the belt or fluid that might have dropped on it. An oily belt will slip and not charge properly. Look for a leak coming from the power steering pump directly above. A bad power steering pump seal will leak into the windings of the alternator and short it out.

    4

    Use an automotive stethoscope or long-handled screwdriver to listen to the alternator while the engine runs at idle. Listen for a "howling" or "grating" noise when you place the stethoscope or screwdriver against the alternator case. A light humming sound is normal. A louder grating noise indicates bad alternator shaft bearings or races. See if the pulley wobbles. A wobbling pulley in conjunction with a grating noise confirms bad shaft bearings or races in the alternator.

    5

    Hook up a voltmeter to the car's battery. Place the positive (red) voltmeter clip on the positive (red) battery terminal post, and the black clip on the battery negative (black) terminal post. Look at the reading displayed in charging volts. The charging volts should range between 14 and 15 volts. A drop under 13.8 volts indicates a problem with the alternator armature and windings.

    6

    Hook up an ammeter to the battery, with the engine off. Remove the wire from the terminal marked "B" on the alternator and connect it to the negative post on the ammeter. Connect the positive lead on the ammeter to the "B" terminal on the alternator. Have an assistant start the engine and let it idle. The standard amp reading should be 10 amps or less (consult your manual for the exact number). Have your assistant raise the engine speed to 2,000 rpm and turn on all of the accessories--high beams, air conditioning and heater to their highest settings. Read the ammeter. The amp draw should be 30 amps or more. Any number less indicates a bad alternator.

    7

    Trace the large "B" wire coming from the alternator and find any fuseable links along its path. Open the fuse links and check for any blown fuses or melted fuse wire. Replace if necessary. Inspect the main fuse box panel, located in the engine compartment, glove box or side kick panel. Find any battery or charging fuses on the fuse diagram and replace any defective fuses.

Problems Caused by Using the Wrong Oil for a Car

"It's more than just oil. It's liquid engineering." This little snippet isn't just a tagline for Castrol motor oil -- it sums up the purpose and principles behind all motor oil. Oil isn't just some slippery stuff that keeps things slick -- it's at least as complex and vital to your engine as blood is to the human body. Using the wrong kind may not result in immediate disaster, but manufacturers are generally pretty good about knowing what's best for their vehicles' engines.

Extremes

    There are three factors that set one kind of oil apart from another: its viscosity or "weight," its composition (regular or synthetic) and the additives it contains. Each of these three factors contribute to how an oil behaves in your engine, what it protects, when it works best and what kind of abuse it can take. Manufacturers build engines with specific performance criteria in mind, and there's no hyperbole in saying that -- in many cases -- they design the engine around the oil it's going to use.

Oil Viscosity

    A numerically higher-weight oil is thicker than a numerically lower-weight oil. For example, an average car might use a fairly thin 30W, while chainsaws and gearboxes will use a very thick 90W type. This rating is critical because oil thins out with heat caused either by friction or by ambient conditions, and thin oil doesn't protect as well as thick oils do. Most oils on the market today are multi-viscosity types, meaning that they contain additives that make them act like a thinner oil at low temperatures and a thicker one at high temperatures. One example would be a 5W-30, which is as thin as a 5W when cold, but maintains the viscosity of a 30W when hot.

Consequences of Changing Viscosity

    Using a thicker oil will generally protect the engine better, but will also reduce fuel economy and horsepower, and increase starting difficulty in low temperatures. Using a thinner oil is more risky, since doing so decreases protection for the bearings, but thinner oil will perform better at low temperatures and increase fuel economy and power output.

Synthetic vs. Regular Oil

    Most synthetics on the market today aren't full synthetics, meaning that they don't use a 100-percent, full-synthetic base stock. Rather, they use a roughly 80/20 mix of high-grade mineral oil and synthetic molecules. This might not sound like much, but the synthetic molecules present are far "larger" and "softer" on a molecular level than the mineral oil molecules. This means that they'll bear the brunt of engine shear stresses, and will help the mineral oil -- which is really just a carrier for the synthetic -- to last longer and perform better than it otherwise would.

Consequences of Changing Oil Type

    Using a full synthetic oil in any engine is never a bad idea, but using a natural oil in an engine that calls for synthetic is asking for trouble. Cases such as this are prime examples of an engine designed for its oil, and odds are that if your manufacturer recommends it, then the engine needs it. Turbocharged engines will always last longer with synthetic oil, and may completely fry without it. Some engines, like Chrysler's sludge-prone early 2.7-liter V-6, don't specifically call for synthetic oil, but will eventually fail without it.

Additives in Oil

    Most gasoline engines don't need an oil with any specific type of non-standard additive, but diesel engines and transmissions do. Diesel oil contains a number of detergents and buffering agents to help it deal with soot and other junk produced by the diesel combustion process. Running a diesel oil in a gas engine will scrub it nearly as clean as it was when it left the show-room floor, which makes it perfect for flushing before switching to a synthetic, but it's not suited for long-term use in gas engines. If flushing the engine, leave the diesel oil in for around 500 miles and then flush and replace it with synthetic. Any more than that and you risk damage to the bearings. Never use a gasoline-grade oil in a diesel; it'll quickly cook, turn into sludge and kill your engine.

Transmission Fluid in Oil

    Transmission fluid is a variation on engine oil, but is far thinner and contains more friction modifiers and detergents than diesel oil does. Old mechanics with several cars and a pit-bull in the yard will often drop a quart of Dextron III into an engine about 50 miles before its yearly oil change to dissolve sludge and clean the motor out.