تاريخ : Sun 21 Dec 2008 | 4 PM | نویسنده : علیرضا راجح پور
 

          

AUTOMOBILE MAINTENANCE AND REPAIR TUTORIAL

Presented by Cities Annex

TABLE OF CONTENTS

Introduction
Philosophy
Disclaimer
General Safety Procedures
Repair outline #1: Shock absorbers and struts
Repair outline #2: Car starter
Repair outline #3: Disc brake pads
Repair outline #4: Disc brake calipers
Repair outline #5: Disc brake rotors
Repair outline #6: Engine
Repair outline #7: Automatic transmission
Repair outline #8: Car air conditioner

INTRODUCTION

 This tutorial is designed to assist the do-it-yourselfer with performing automobile repairs. It is structured around problem areas, such as "my car won't start", encapsulating the problem area with an overview of the diagnosis and repair. It uniquely addresses maintenance and repair items at a summary level to provide a valuable supplement to detailed service and maintenance manuals. It addresses simpler areas, such as dealing with bad shocks, as well as complex areas, such as engine rebuilding and air conditioning repairs.

The goal of this tutorial is to support the do-it-yourselfer pursuing the goal of low cost, high quality, automobile transportation to the 200,000-mile vehicle life milestone and beyond.

PHILOSOPHY

Airplanes have a service life of forty years or longer. So why not cars? Cars can, and do, easily run 200,000 miles and more, and 20 years or longer, if given the proper maintenance.

The do-it-yourselfer (shade tree mechanic) remains in a position to run his/her car to the 200K-mile mark and beyond because of the massive amounts they can save on labor. These savings can pay for the tools and parts to not only pay for immediate repairs needed, but to implement thorough preventive maintenance as well.

For example, go to a repair shop with a bad alternator. You'll probably come out with a bill for $200 or more ($125 for a remanufactured alternator and $75 to diagnose the problem and replace the alternator). You may soon be back with a bad battery, bad alternator or bad drive belt, but those are new repairs. and they can "nickel and dime" you to death. Each of these problems can leave you stranded with a car that won't start and has to be towed to the shop. A few of these problems will soon have you feeling that your nice new car has turned into a clunker and reached the end of it's useful life. You may cast away a good car, even though it only has 80,000 miles on it, and opt to be saddled with new or larger monthly car payments rather than chance breaking down on the highway.

An alternative is to do the repair yourself, and throw in preventive maintenance as well, by rebuilding the whole charging system. You can replace the alternator, voltage regulator, battery and drive belt for about the same amount of money (assuming you buy the parts at a discount from a discount auto store, mail order firm or online car parts center). Then you can forget the whole charging system for several more years and many tens of thousands of miles, and not have your car turn into an unreliable clunker.

The key to keeping your car from turning into an unreliable clunker is to perform good preventive maintenance. If two tires are worn and two are marginal, replace all four.. If the shocks are getting old, replace all four at once. If the heater and radiator hoses are old, drain the antifreeze and replace all of them at once. When a drive belt gets worn, replace all of them at once. Going for 200K miles, if your engine smokes, rebuild the whole thing. If your transmission slips, rebuild it and throw in a new/remanufactured torque converter. If a front-wheel drive CV joint gets noisy, replace both drive shaft halves, and throw in new wheel bearings while you're at it. When you replace spark plugs, replace the plug wires and distributor cap and rotor at the same time.

By rebuilding systems, you'll save money in the long run and keep your car from becoming an unreliable clunker.

And above all, be sure to change your engine oil and filter religiously every three to five thousand miles (three if your trips are short). If you do this, you might even get 200K miles without an engine rebuild, but if you do have to rebuild the engine you may not have to have your cylinders bored ... a savings of several hundred dollars.

The do-it-yourselfer must be prepared to accept blotching an occasional repair. It's part of the learning process. When this happens, accept your misfortune and do the repair over again, or accept temporary defeat and take your car over to your favorite professional mechanic. Just be polite, be humble, bow your head and admit your failings, hand him the parts in a basket, then shut up and let him do the job. Being diplomatic with a blotched job is the mark of the seasoned shade tree mechanic.

Even with blotching a job here and there, you'll save money in the long run and be able to afford keeping your car in like-new running condition long after others have hit the bone yard.

Save a bundle of money on labor doing your own repairs, but don't cut corners on tools and parts. You'll watch your neighbors go through three or four cars while you go through one. Then take the money you save on car payments and go buy yourself a nice classic. It'll be a lot of fun to own and drive, it'll turn heads going down the street, and you'll probably sell it for more than you paid for it.

 

 

DISCLAIMER

This tutorial on auto repairs is only an overview of procedures. It is not intended to be a substitute for professional instructions and/or directions. All auto repairs should be performed according to the automobile manufacturer's factory maintenance and repair manuals.

The general safety procedures listed in this tutorial are not exclusive. Other, more detailed and specific safety instructions are found in the factory repair manuals and must be read, understood and followed when performing auto repairs to avoid the risk of serious injury or death.

GENERAL SAFETY PROCEDURES

Following is an abbreviated list of general safety procedures to follow when working on you automobile. As discussed in the Disclaimer above, they are not exclusive.

1. Never trust a jack to hold your car up while you get under it. Jacks can, an often do, slip or fall over, allowing the car to fall. If you are going to work under the car, it must be supported on quality jack stands. Two jack stands are better than one.

Jack stands can sink into hot asphalt under the weight of a car. When working on asphalt, place a 12" x 12" or larger piece of plywood under the jack stands.

2. Do not attempt to remove engines or transmissions without the proper lifting and/or supporting equipment. A falling transmission can kill you. An engine that suddenly shifts while pulling it can result in fractured bones or lost fingers. Never attempt heavy jobs like these without an assistant.

3. Always disconnect your battery at the terminals before working on your car. An accidental short with created with a metal tool can result in serious burns.

4. Remove rings and loose clothing before working on your car. Loose clothing can easily get caught in rotating machinery. If a metal ring becomes part of an electrical short, serious burns can result.

5. Be extra cautious with flammable liquids, especially gasoline. Gasoline is nearly explosive, even in the open. A single spark can ignite gasoline with disastrous results.

Never work in an enclosed space if there can be flammable fumes, especially from gasoline or cleaning solvents. Good ventilation, like a nice outdoor breeze, is desirable when working with flammable liquids. Needless to say, don't smoke around flammable liquids.

Make sure there is an approved fire extinguisher in your work area, where you can get at it in a hurry if you need to. Make sure you know how to use it before an emergency arises.

6. Always wear eye protection when working on your car. Slipping tools, falling parts and debris, splashing liquids, flying dust and other eye hazards are the order of the day.

7. Be extremely cautious around a running engine. Also watch out for electric cooling fans that can start up by surprise, even with the ignition turned off and the engine not running

8. Engines and exhaust systems get real hot and can burn you real bad. Make sure everything is cool before working on it. Remember, too, that hot crankcase oil can result in serious burns. Let your engine cool, even if it takes and hour or two, before attempting an oil change.


9. Air conditioning systems call for special handling. Do not vent refrigerant into the atmosphere. Take your car to a professional shop and have them remove the refrigerant before attempting repairs. If adding refrigerant yourself, wear good goggles. A refrigerant line or fitting can burst under high pressure, shooting refrigerant into your eyes and blinding you.

10. Exhaust fumes contain deadly gases, like carbon monoxide, a colorless, odorless gas. Never work in an enclosed space, such as a garage, with your car engine running. Not even for a brief moment.

11. Always assume your hand tool will slip, then ask yourself what your hand will hit will hit when it does. You be the judge if the skinned knuckles will be worth taking the chance. Wear a glove and save your knuckles.

12. Always chock the wheels on your car when raising your car, even on level ground. This helps prevent the car from rolling off the jack and/or jack stands and falling on you.

 

Repair outline #1: Shock absorbers and strut cartridges

 Problem: Car bounces and sways ... uneven tire wear.

Shock absorbers should last twenty to thirty thousand miles. Strut cartridges should last forty to sixty thousand miles. Struts are typically found on the front of cars and shocks are typically found on the rear, but there are variations to this theme.

Sometimes, a bad shock leaks hydraulic fluid, which then collects road dust. A visual inspection of the shock should reveal if the shock is leaking. There may be no other symptoms, but a leaking shock should be replaced because it will soon cease to function properly.

Another problem can be loose nuts or bolts on the shock absorber mounting studs or brackets. This may reveal itself as a thumping or banging noise when you drive over bumps, as well as by visual inspection.

When shocks or struts wear out, your car will bounce a lot when you drive over bumps. It will also sway a lot when you go into a turn. You may also find uneven wear patterns on your tires.

Bad shocks and/or struts lead to serious handling problems with your vehicle and should be replaced before they get to this point. They should always be replaced in pairs. If possible, replace struts/shocks on all four wheels at once.

Shock absorbers can usually be replaced by the do-it-yourselfer equipped with basic mechanic's tools, a pair of quality jack stands and a maintenance/repair manual specific to the vehicle. Plan on spending a day in the driveway or garage the first time, and half a day the second time.

Most strut cartridges are more difficult to replace, especially when the strut cartridges are mounted inside the coil springs. These designs require disassembly of the steering linkage. They also require a pair of coil spring compressors. Working with a compressed spring is dangerous and can result in serious injury if a mistake is made. So if you are going to replace this type of strut cartridge yourself, get a knowledgeable friend to help the first time. Some strut designs do not require compressing the springs. The cartridges on these designs are mounted outside the coil spring and are much less of a problem to replace. Your maintenance/repair manual should explain which type you have, and how to replace them.

When you remove springs to replace strut cartridges, be sure to inspect or replace the bearing assembly that the spring rotates on with many designs. The bearing will be found at the top of the spring.

If you have to disassemble the steering linkage to remove the strut cartridges, be sure to have the front end re-aligned immediately afterwards.

Repair outline #2: Car starter

Problem: Car won't start

If you turn your ignition key to the start position and your car won't start, the problem could be your starter.

The starter turns the engine, so if your engine turns over, the starter is not bad.

If the engine won't turn over, first eliminate other problems, such as

(a) A dead battery or corroded battery terminals. Turn on your headlights and interior lights, and then try to start your car. Have an assistant tell you if the headlights dim a lot, while you also watch the interior lights. If they do, and the engine won't turn over, suspect a bad battery or corroded battery terminals. You might also hear your starter's solenoid click or chatter, as the light dim, if the battery is weak or it's terminals are corroded.

(b) A bad starter solenoid (if it is separate from your starter). If your battery and battery terminals are in good shape, you should hear the starter solenoid click once each time you turn the ignition to the start position. If not, suspect the solenoid. But before the final verdict, make sure there are not defective interlock switches, such as a park switch (with automatic transmissions) or a clutch switch (with manual transmissions) that prevent you from starting your car with gears engaged.

If, after performing the above tests, you're still not sure what the problem is, and your starter has over 50,000 miles on it, consider replacing it (as well as the starter solenoid), as preventive maintenance, or, quite possibly, to solve the problem. And if your battery is more than four years old, replace it too.

Repair outline #3: Disc brake pads

Problem: Disc brakes squeal

Some disc brake pads have wear sensors. When the pads wear down, the sensor starts touching the rotor causing a high-pitched squeal. The solution to this problem is to replace the pads immediately, before the meal wear sensors damage the rotors. When pads without wear sensors wear down to nothing, the metal backing on the pads begins wearing away the rotors with a grinding noise when the brakes are applied. When this happens, expect to replace the rotors as well as the pads. If the damage is mild, you may get away with having them resurfaced. To avoid damage to your disc brake rotors, check your pads every 10,000 miles.

If you have a damaged rotor, resurface or replace both sides at once. Keep them matched.

Sometimes, brakes squeal for no obvious reason. When rebuilding brakes, be sure to clean any rust from sliding metal surfaces and make sure all anti-rattle springs and other parts are installed. Anti-squeal compound may also help. If you've taken every precaution and the brakes still squeal, try a different brand of pads.

Repair outline #4. Disc brake calipers

Problem: Disc brake pull to one side

When your disk brakes pull to one side, you may have a sticking caliper. A sticking caliper can cause the brake to be slightly applied, causing the pad to overheat and brake with less force than the other side. If this condition exits for long, the pad under the sticking caliper will quickly wear out. When you inspect the pads, you will find the side with the sticking caliper worn much more than the other side. In fact, you may find a damaged rotor.

The solution is to replace the damaged caliper. . Don't try to rebuild the calipers. Quality inexpensive remanufactured calipers are available. Replace them on both sides at once. If a rotor is damaged, replace them in pairs also.

Repair outline #5. Disc brake rotors

Problem: Disc brakes pulsate

When disc brake rotors wear unevenly, they may pulsate when the brakes are applied. However, anti-lock brakes can do this under normal conditions. If in doubt about the condition of your rotors, have them resurfaced or replaced. Always resurface or replace rotors in pairs to keep both sides matched.

 

 

Repair outline #6:  Engine

Problem: Engine smokes

A worn engine can smoke because oil leaks into the cylinders around worn valve guides, or the oil rings are worn, or both. These conditions will create white smoke, which is burning oil, as opposed to a rich fuel problem, which will create black smoke, which is burning fuel.

If you get a puff of white smoke when you start your engine, after it has been sitting for hours, that's probably due to worn valve guides. Oil laying on the cylinder heads leaks into the cylinders while the car sits. Since the engine isn't running, the oil accumulates enough to cause visible smoke for a moment when the engine is started.

As long as the smoking engine doesn't foul spark plugs to often and can still pass emission tests, there's no big rush to do anything. Your can plan this job, making arrangements for other transportation while the car is out of service. But don't procrastinate too long. If you do, you'll soon find yourself wanting to rid yourself of a clunker.

I your car suddenly begins belching out white smoke, you can't wait. Something broke. Park it immediately and begin planning an engine rebuild or replacement.

An engine that smokes (white smoke) is getting tired. It needs rebuilt ... completely rebuilt. There's no sense in doing half a job. Bite the bullet and take your car or engine to your favorite engine re-builder, or take it apart and go to your auto machine shop with the parts. Don't cut corners ... get the cylinders bored if out of specs ... get the block deck and cylinder head(s) resurfaced ... have the rods reconditioned ... get the heads rebuilt ... replace the crankshaft if it's scored. Get a master engine kit that includes piston rings (pistons too if the cylinders were rebored), main, rod and camshaft bearing, a new camshaft (stock) and lifters, timing gears and timing chain, oil pump (normal volume), freeze plugs, gaskets and seals. And while you're at it, throw in a new water pump.

Don't attempt an engine rebuild yourself without good manuals and precision tools. And make sure you have the assistance of someone that knows what they're doing the first time.

Always rebuild your engine as it was originally (stock or OEM) if you want to minimize hassles, like emissions problems, and want to get a long engine life.

For some cars, exact factory replacement engines are available at a surprising good price. These are called factory crate engines. Not only are they brand new engines made by the car manufacturer, they carry a decent warranty. Check with your car dealer for this option. Then shop around between dealers, mail order and online suppliers to make sure you get a good price. You may find a large variation in prices.

Do not attempt to rebuild an engine in the car. You can't do the job right and you will probably risk injury. Get a quality engine lift and pull the engine. You'll save hassles in the long run and be able to do the job right. If your car is high mileage (over 100K miles), you may want to pull the engine and transmission together and rebuild them both at once.

Repair outline #7: Automatic transmission

Problem: Transmission slips during gear shifts

An old automatic transmission often starts slipping between shifts. This can be due to worn clutch discs or bands.

If you're good at other car repairs, why not tackle and automatic transmission repair? A rebuild kit will set you back only a fraction the cost of a new or rebuilt transmission.

You'll probably need a day to pull the transmission (with help of an assistant), a day to take it apart, a day to inspect all the parts, a day to put it back together and a day to put it back in your car (with assistance again). If you've done this before, the time will be much less.

You'll also make a big mess with spilled transmission fluid so protect your garage floor with lots of newspaper and have lots of sawdust to soak up spills. You'll need lots of working surfaces to spread out all the parts in the order you remove them. A couple of cheap folding tables should do the trick if you need to improvise working surfaces. Finally, buy or borrow any special tools your manual calls for. If you're creative, you can probably improvise or even fabricate the special tools.

Above all, be patient and attentive to detail when rebuilding an automatic transmission, and follow a good manual step by step.

Don't cut any corners. Inspect all hard parts, like shafts and gears, and replace them if damaged or worn. You may have to go to a car dealer or transmission shop to buy these parts, or pick up a sacrificial transmission from the bone yard. Replace that old torque converter with a quality new or rebuilt converter.

Repair outline #8: Car air conditioner

Problem: Air conditioner doesn't cool

Automotive air conditioners usually cost a bundle to have them repaired. It takes special training, equipment and parts to do the job right. Because of the high cost of repairs, many people decide not to have the repairs done. They suffer in the heat and start thinking about trading in their clunker.

Many car air conditioner repairs can be done by the do-it-yourselfer, giving fresh life to their car.

The simplest repair is replacing a broken or slipping compressor drive belt, so start with an inspection and/or adjustment of the belt.

Next, check your refrigerant charge and add refrigerant if needed. You'll need an auto air conditioner pressure gage and a refill kit. You'll need to determine if your system uses the older R12 or the newer R134 refrigerant (look for a label under the hood). You must wear goggles when adding refrigerant to avoid being blinded if refrigerant gets in your eyes. If your air conditioner is one of the newer R134 systems, you're in luck.

See if your air conditioner clutch engages and turns the compressor with the AC on and the engine running. If not, or if it cycles on briefly, then back off, the refrigerant charge may be low. Attach the pressure gage to the high-pressure line and monitor the pressure. If the AC clutch never engages, you may have to hotwire the clutch directly from the battery to make it engage. Once the clutch engages, see if the high pressure reaches the factory recommended value. If not, add refrigerant to the low pressure fitting, until the factory recommended pressure is achieved (or about 80% of that for R12 systems retrofitted to R134).

You can buy R134 in small cans at your local auto store, but you can't buy R12. If your system uses R12 and needs a charge, get out you checkbook and go over to the repair shop, since professional shops can still get R12 (it costs a small fortune). Before adding R12, the shop will probably insist on finding and repairing any leaks, adding to the costs.

If you have the older R12 system, you might want to consider converting to R134. A repair shop can do this (bring your banker along) or you can take a chance a do it yourself. Inexpensive retrofit kits are now available at your local auto parts store. The kits include high and low-pressure Schrader valve adapters (because R12 and R134 fittings are different), a can of a special R134-compatible oil charge, a refilling hose, and a couple cans of R134. Be sure you have a high-pressure gage that connects to the new R134 fittings. Remove the old R12. Be responsible and go over to the auto air conditioning shop to have the R12 removed, so as to not contribute to damage to the earth's ozone layer and get in trouble with the law. Follow the kit's instructions and install the R134 retrofit fittings on the existing R12 Schrader valves ... then add the oil charge and the R134 charge up to the kit's recommended pressure. Don't expect a retrofit to freeze you out. R134 is not as good a refrigerant as R12, but it will do the job if the rest of the system is working OK. Also, professionals will probably advise you not to conduct this simple retrofit, insisting that you'll risk damaging your system with incompatible compressor oils. So you be the judge ... pay their lofty price for a professional retrofit or do it yourself for next to nothing and risk a blotched job. If your AC doesn't work, and you can't afford to pay for a professional retrofit, and you can't take the heat, ask yourself if you have much to loose trying the retrofit. Ask around and you'll probably find people that got away with the do-it-yourself retrofit and are pleased with the results.

If you have a seized compressor or compressor clutch, and have some experience working with automotive air conditioning systems, go ahead and replace the compressor with a quality rebuilt unit (in some systems, it's best to replace the compressor and clutch as an assembly). Again, have the refrigerant professionally removed. Make every attempt possible to avoid having much air enter the system. Air does not compress easily and carries moisture. Both are a big problem. The moisture will condense inside the system and combine with refrigerant to create a corrosive acid that damages components. Air can overload the compressor and damage it. Any air and moisture that gets into the system must be drawn out with a vacuum pump before adding fresh refrigerant. So have a suitable vacuum pump ready or don't attempt the job. It is also advisable to replace the drier in your AC system. It's purpose is to capture any moister you missed with the vacuum pump.

Links and References:

http://dr_hess.tripod.com/strut_replacement.htm

 



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