All FAQ
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How to Do a Compression TestA compression test reveals the condition of your engine's valves, its valve seats, and piston rings and whether these parts are wearing evenly. Healthy engines should have compression over 100 psi per cylinder, with no more than 10 percent variation between the highest and lowest readings. With a compression tester, a few hand tools, and 20 minutes, you can try this yourself.STEP 1 Remove the fuel pump and fuel-injection fuses. Disconnect the main wire to the coil and spark plug wires; remove spark plugs.STEP 2 Start the threaded end of the compression gauge in a spark plug hole by hand.STEP 3 Turn the ignition on, depress the throttle, and crank the engine four revolutions. This should result in a stable reading; if not, crank up to 10 revolutions, but do the same with all cylinders.STEP 4 Mark the pressure reading for each cylinder on the valve cover in chalk, then move to the next cylinder.TIP For a cylinder below 100 psi, pour 1 teaspoon of engine oil into the plug hole and retest. If the reading jumps, the piston rings are worn. If not, think valve problems.
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Tools Needed for Bleeding Your Car's BrakesHand-held vacuum pumpNew brake fluid (type recommended for your brake system)Floor jackJack standLug wrenchLine wrench (10mm or 11mm)Shop towelsTeflon tape, if necessaryGrease, if necessaryVehicle repair manual, if necessary1.Four Tips for Successful Brake System BleedingCheck the sequence the manufacturer recommends when bleeding your particular vehicle model and stick to that order. Consult your car owner's manual or vehicle repair manual.Always use new brake fluid when bleeding the brake system: Once you open a container of brake fluid, it begins to accumulate humidity. So using brake fluid a few weeks old will rust components in your brake system at a rapid rate. That's why manufacturers recommend replacing the brake fluid in your car every two or three years.To make your job easier, before you start bleeding a brake line, remove the bleeder screw from the caliper or wheel cylinder and apply some Teflon tape (about three turns) to the threads and replace the screw.After connecting the tube fitting from the pump to the bleeder screw, cover the fitting and screw union with grease (any type). This will prevent introducing air bubbles into the stream that might confuse you with the regular air (if any) you want to purge out of the system.2. What You Need to Know About the ABS in Your CarIf you own a 1996 or older model with ABS system that connects to the four wheels, and you want to bleed air out of the brake master cylinder or hydraulic control unit (HCU), most likely you'll need a special adapter or device for the control module to purge air from the HCU.Also, if you need to work on a master cylinder that comes with the pressure modulator (aka ABS actuator) as part of the unit, you may need special equipment. For example, depending on your particular model, you may need a special electronic device or special scan tool to operate the solenoids, valves, and pump during the bleeding procedure. So you may need to take your vehicle to the shop for service.Consult the service manual for your particular make and model for more information, especially if you own a GM vehicle.3. How to Bleed the Brakes Using a Vacuum Pump1. Before you remove the cap, wipe the brake master cylinder clean with a shop rag to get rid of grease and dust so you don't contaminate the brake hydraulic system, and follow the next suggestions:When flushing the system, remove as much fluid from the reservoir using your vacuum pump or turkey baster and add new brake fluid up to the MAX mark.Loosen the cap on the reservoir but don't tighten it. Keep the cap on the reservoir opening though. This will prevent forming a vacuum during the procedure.Watch the fluid level and don't let it go beyond the MIN mark to keep air out of the system during the bleeding or flushing procedure. Otherwise, you'll need to start purging the system all over again.2. Ready your vacuum pump by connecting the reservoir jar and the appropriate tubing and adapter that will connect the jar to the bleeder valve or screw in the wheel cylinder or caliper to prevent outside air from being sucked into the jar as much as possible.3. Depending on your vehicle make and model, you may need to remove the wheel on the assembly you need to work on to reach and work comfortably during the bleeding procedure. If necessary, loosen the lug nuts on the wheel, raise the wheel with a floor jack, secure the vehicle with a jack stand and remove the wheel.4. Thoroughly clean the bleeder screw to prevent oil or grease from entering and blocking the bleeding tube.5. Choose the correct line wrench size to turn the bleeder screw open and close. Place the wrench in position, if necessary, before connecting the bleeding tubing to the bleeder screw.6. Loosen the bleeder screw, but don't force it; if necessary, spray some penetrating oil on the screw and tap the screw lightly with a rubber mallet or hammer. Then try loosening the screw.7. Connect the bleeder tubing to the bleeder screw.8. Without starting the engine, pump the brake pedal at normal foot pressure, about 10 times, to get rid of any residual vacuum out of the brake booster.NOTE: Watch the fluid level in the reservoir as you bleed the lines, or you'll bring air back into the system and you'll have to start the bleeding procedure all over again.9. Add brake fluid to the brake master cylinder reservoir to bring the level up to the MAX mark, if necessary. Place the lid back on the master cylinder reservoir but don't tighten it.10. When ready, squeeze the pump handle 15 times.11. Then, turn the bleeder screw or valve open about 1/2-inch. This will cause brake fluid to flow into the bleeder jar.12. Watch the size of the bubbles in the stream of fluid going into the jar. Keep pumping until the fluid level in the jar is about an inch from the cap.13. Tighten the bleeder screw, and remove the fluid collected in the jar; reinstall the jar and repeat steps 9 through 13, until you have purged or flushed the line.14. Add new brake fluid to the master cylinder reservoir, if necessary.15. When ready, move on to the next wheel assembly and repeat the procedure to bleed the brake line.16. When you finish bleeding the four brake lines, check that you have tightened all bleeding screws. After depressing the brake pedal several times, examine the bleeding screws for leaks.17. Verify that the brakes feel solid (not spongy); hold your foot on the brake pedal applying normal stopping pressure. The pedal should hold pressure without falling to the floor. Otherwise, there's air in the system you need to purge.18. Carefully, test drive your car around the block at low speed to confirm the repair.4. Do I Need to Bleed All Four Lines?You don't necessarily need to bleed all four lines from the system. For example, if you replace a single brake caliper, wheel cylinder, or rubber hose, you only need to bleed that line.However, you need to bleed all four brake lines if:you had to remove or disconnect the brake master cylinder for repairs.the fluid level dropped drastically in the reservoir.you feel a spongy brake pedal.Consult your car owner's manual or repair manual for more information5. How to Bleed the Brake Master CylinderGet your vacuum pump ready by connecting the pump's reservoir jar with a piece of tubing. Then attach a length of tubing of the appropriate size to the reservoir jar; you'll need to connect the other end of the tubing to the master cylinder's ports, in turn, during the bleeding procedure. Use tubing and adapters of the appropriate diameter that come with your kit. (Usually, manufacturers include a couple of plastic tubes and plugs with their units for bleeding as well.)Ask an assistant to hold the piece in place during the bleeding process with the push-rod end at a slightly higher angle than the opposite end. Or you can use a vise, but be careful not to damage the cylinder's body when securing it to the vise.Fill the cylinder reservoir with new brake fluid. Use the fluid type recommended by your vehicle manufacturer. During the bleeding procedure, don't let the brake fluid reach bottom to prevent air from entering the cylinder; otherwise, you'll need to start the bleeding process all over again.Unplug one of the cylinder ports and plug in the vacuum pump to it.Pump the cylinder until you see brake fluid free of bubbles entering the pump's reservoir jar.Disconnect the pump from the outlet port and tightly plug the port.Repeat the bleeding procedure in the other port(s).Now, with all the ports plugged, position the cylinder push-rod end at a slightly lower angle than the opposite end.Then, use a Phillips screwdriver or a punch to slide the cylinder push rod in and out about 1/8 inches. Repeat until you see no bubbles in the master cylinder reservoir.Raise the angle of the push-rod end again and bleed the cylinder again through the ports.Now you can install your new brake master cylinder.
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How to Use a Motorcycle Chain Tool Using a Motorcycle Chain Tool to Break a ChainStep 1. Insert the extractor spring and the extractor pin into the body bolt, then screw the extractor pin guide into the end of the body bolt until it's finger tight.Step 2. Back off the extractor bolt until the extractor pin is recessed about 2mm into the extractor pin guide.Step 3. Position the tool over the chain, and align the extractor pin with the pin of the chain you want to push out.Step 4. Tighten the body bolt so it is snug against the chain and is securing it in place.Step 5. Use a wrench to tighten the extractor bolt and drive the pin out from the chain. NOTE: There will be a lot of resistance at first, but once the pin is broken loose the resistance will lessen.Step 6. Once the pin has been pushed through, back off the extractor bolt, then the back off the body bolt, and remove the old chain.Using a Motorcycle Chain Tool to Make a Chain - Clip MethodStep 1. Using a digital caliper, measure the distance between the outer plates of the new chain you'll be installing.Step 2. Grease the new chain's master link, outer plate and the O-rings. NOTE: Never assemble a new chain without greasing the parts first.Step 3. Put an O-ring on each of the new master link's pins, then install the master link into the chain. Next, install another O-ring on each of the pins and then install the outer plate.Step 4. Back off the extractor bolt so the extractor pin is retracted within the body bolt, and install the press plate to the extractor pin guide.Step 5. Position the tool over the chain, and align the press plate with the pins of the new master link.Step 6. Slowly tighten the body bolt so it presses the new outer plate down onto the pins. The outer plate must not be too tight, or it will compress the O-rings and cause the chain to kink. Tighten the body bolt a half turn, then stop and measure the distance between the outer plates of the new master link. Continue tightening, pausing and remeasuring until the chain measurement is correct.Step 7. Install the new chain clip to the new master link. Make sure the front of the clip (the enclosed end) is facing the direction the chain will be travelling in when the motorcycle is running.
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CV jointsWhile the wheel has remained more or less round since its inception, the axle has evolved to spin in all manner of configurations and situations. Insofar as automobiles are concerned, there are more than a few different types of axles. Some are of the short and stubby variety like the spindles upon which nondriven wheels spin. Things get more complicated, however, when the axles have to deliver power to the wheels. If a powered wheel had nothing to do but roll on a perfectly smooth surface, the solution would be simple. A straight axle with no suspension would do the job. As anybody who has recently driven around can attest, roads are everything but perfectly smooth; thus, the axle must be able to deliver power to the wheels and travel with the suspension as it soaks up the bumps.This gets particularly tricky in the case of a front-wheel-drive car, where the wheels are steering the vehicle as well. With all the angles created by the suspension traveling over the bumps and wheels steering to and fro, the axle must be as flexible as a gymnast while spinning like a whirling dervish. The solution was to make axles with constant velocity (CV) joints. Front-wheel, all-wheel and certain rear-wheel-drive vehicles with independent suspensions also use this same type of axle, which employs two CV joints to deliver flexible power to the wheels. Some vehicles even employ CV joint axles in the drivelines.Assessing axle wearA CV joint is a collection of bearings and cages that allows for axle rotation and power delivery on a number of different angles and planes and enables the axle to change length as it travels up and down. All the parts spin around in a protective layer of grease that is held inside the joint by a flexible, rubber boot. Without the boot, the grease would simply spin out of the CV joints. The boot also keeps dirt and grime out. On the CV axle are two CV joints along with one or two sets of splines. One side of the axle gets power from the engine while the other delivers the power to the driven wheel. Presto.Over time the rubber boots of the CV joints can become cracked, torn or otherwise compromised. Once moisture and dirt get into a CV joint axle and grease makes its way out, the CV joint’s days are numbered. Signs of impending failures are a click-click-clicking or metallic crackling noise while turning and accelerating or a clunking upon deceleration. While one can repack, reboot and rebuild CV axles, it makes more sense for the average do-it-yourselfer to procure replacement units and swap out the old axles. If a boot is torn or missing, it is possible to save the joint if caught early enough, but usually the damage has already been done. Replacing or servicing the entire CV joint axle assembly may be the smarter move since replacing a boot may involve removing an axle, which may also involve removing half or all of the vehicle’s brakes and suspension.Replacing CV joint axlesWhile the basic concept of a CV joint axle is the same from vehicle to vehicle, there are a number of different peculiarities that make access to a service manual an important first step before disassembly. Axle pullers and impact wrenches may be required. Pry bars, c-clips and snap rings inside differentials may also be part of the bargain. This knowledge is best gained before getting started, not while 90-weight gear oil is dripping down your sleeve.How-to steps for replacing two CV joint axlesStep 1: This is a rear drive vehicle with two CV joint axles. Start by disconnecting the battery, jacking up the vehicle and allowing some penetrating oil to soak into any retaining bolts.Step 2: In this case, suspension disassembly was not required. Moving brake lines and other obstacles out of the way of wrenches is a good bet before beginning.Step 3: Loosening but not removing the strut top mounts and sway bar end link bushings can provide a bit more suspension travel for easier axle removal.Step 4: Loosen and remove the wheel side axle mounting bolts.Step 5: Separate the axle from the wheel. Do not allow the axle to hang from the transmission or differential. Oil seals could be damaged.Step 6: Gently pull, pry or otherwise liberate the axle from the transmission or differential. Do not bend axle seals. Be careful not to tear the transmission or differential oil seals.Step 7: The axle splines on the left show damage. Note the c-clip on both axles.Step 8: Don't forget to transfer any axle seals, ABS rings or other parts to the replacement axles.Step 9: Guide the replacement CV joint axle into place. Depending on the type of retainer, the axle should click firmly in place.Step 10: Always use the proper torque on the axle bolts. Check axle rotation. Reassemble dismantled components.
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Replacing a leaking oil pan is one of the best ways to ensure your engine is receiving the oil it needs, and it can sometimes be done in a matter of a few simple steps. For the lucky few, the source can be a loose oil-pan drain plug, a dipstick tube that’s come unseated from the engine block, or an oil filter that’s either not screwed down or has a cracked gasket.Detect oil leaking from an oil pan To trace oil leaking from an oil pan, begin by cleaning the engine with a degreaser, possibly at the self-service car wash. When external oil reappears, follow the trail to its highest point. Hopefully, the culprit will be one of the offenders listed above. If the evidence leads to the top of the oil pan, however, the solution will be more labor intensive.Installation of oil pan gasket replacement A service manual is a valuable resource when removing the oil pan. Other parts and brackets might need to be removed first to access the pan and its bolts, the locations of which are illustrated in the manual. Vehicle-specific procedures will also be described in the manual, such as if the crankshaft needs to be rotated before the pan will come out. Also read the instructions that come with the oil pan gasket replacement to see what, if any, sealers and chemicals the job requires.The steps here show oil-pan gasket replacement on a front-wheel-drive car. The job is somewhat straightforward, but it can be messy. Be conscientious of a few potential pitfalls: Try not to bend the oil pan when removing it. Attempting to pry the pan loose with a screwdriver can bend the mounting surface. Tapping it with a mallet can actually crack the pan if all bolts aren’t out. (Double-check the bolt count and locations in the manual if the pan doesn’t release easily.) Once the oil pan is off the vehicle, check it for metal shavings to reveal other potential problems. Also clean all sludge out of the pan and inspect for cracks before reinstalling it. h3,.surfaced-item-copy" data-analytics="{ "name": "list" }" style="box-sizing: border-box; margin: 0px 0px 2rem; list-style-type: none; padding-left: 0px; padding-right: 0px; color: rgb(43, 38, 38); font-family: EMprint, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 16px;"Step 1: Obtain the appropriate oil pan gasket replacement. Gasket materials vary depending on what types of metals they’re intended to seal. Name-brand gaskets come with any necessary sealants.Step 2: While the oil is draining, remove the splash shield and bellhousing cover.Step 3: In front-wheel-drive vehicles, the oil pan is often mated to the transaxle. Other accessories such as exhaust-manifold support and air-conditioning bracketry might need to be detached too.Step 4: A service manual helps identify all oil-pan bolt locations. Some might be obscured behind other parts.Step 5: Removing the wheel-well-liner pieces eased access to the outboard passenger's side bolts on this vehicle.Step 6: Once all bolts are removed, the pan can be dropped. If necessary, tap it lightly with a mallet to break the seal.Step 7: Scrape off any gasket residue and clean all sealing surfaces thoroughly with a solvent. Also clean the inside of the oil pan and inspect it for cracks. Then install the new gasket per its instructions. This one uses regular grease to hold it in position.Step 8: Use thread sealer, if specified, then torque the oil pan bolts to spec in a spiral pattern, beginning in the center. Reattach any accessory brackets, refill the crankcase with oil, start the engine and inspect for leaks.
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If your car won't start or it hesitates when you crank it, you might have a bad ignition coil. Testing an ignition coil on most cars is pretty easy. No special tools are required, and you don't even have to remove the coil. Just remember to be careful, because the amount of electricity generated by your ignition system can be dangerous.What the Coil DoesAn ignition coil is a kind of high-voltage transformer. It converts the power from your car's 12-volt battery into the thousand or so volts that the spark plugs need in order to fire and then ignite the engine's air-fuel mixture. Although manufactured to last, ignition coils are not fail-safe. Over time, heat, vibration from the road, and even degraded insulation will necessitate that you change out this part.Safety FirstYou can easily test the coil on your car yourself, either while it's still on the car or after you've removed it. Just take a few precautions first. Make sure you're wearing a pair of safety glasses and old clothing with no loose sleeves or shirttails that can get caught in the engine or elsewhere on the vehicle. Also be aware that your car's engine is an electrical system, so be cautious when you are working on a running engine and avoid those parts and processes that can deliver a shock—or worse.Testing the CoilYou don't have to remove the coil in order to test it. It can be done by checking the spark plugs. For this test, you'll need a pair of safety goggles, some insulated pliers, a spark plug socket tool, and a helper. The test can be done in two easy steps:First, turn off your car's engine. Then consult your owner's manual to locate the wire that attaches to one of your spark plugs. Remove the wire and use a spark plug socket tool to remove the spark plug from its socket. Be careful not to let anything drop into the empty spark plug hole.Next, reattach the spark plug wire. Hold the spark plug with a pair of insulated pliers and touch the threaded bare end of the spark plug to a grounding surface. Pretty much any exposed metal, including the engine itself, will do. Have your helper crank the engine while you look for a bright blue spark to jump across the spark plug gap. If you see a nice, bright spark (clearly visible in daylight) your coil is doing its job.If your coil is already off the car, or if there was no spark or the spark was weak, then move on to bench test your coil. This test will tell you without question whether or not you have a bad ignition coil.
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OverviewIn the old days (generally before 2000), changing your vehicle’s coolant was simple. That procedure is shown in Step 2, below. After 2000, cars got more complex and many DIYers got intimidated by the precise filling and “air-bleeding” procedures required to eliminate engine air pockets. But don’t worry, it’s easier than it looks. All it takes to get back in the game is a one-time $83 investment in an air-powered refilling tool. The details follow in Step 3.Either way, you can change your coolant yourself in about an hour. But before you do anything, check your owner’s manual for the recommended procedures and coolant for your car.Draining and refilling coolant in older carsHow to Put Coolant in a Car1.How to drain a radiator.Open drain cock ,Open the drain cock by unscrewing, twisting a quarter turn, or twisting and pulling. 2.Remove the hose,Push together the clamp spring with a slip-joint pliers and slip the clamp away from the neck. Pull the hose free and drain the remaining coolant. If access is difficult, a hose clamp pliers saves time and bruised knuckles.3.Hose clamp pliers are available at auto parts stores or online.4.Add coolant, Stir 1 gallon of full-strength (not premixed) coolant and 1 gallon of distilled water together in a clean bucket before adding the mix to the radiator.If you’re way past due for a coolant change and your cooling system is corroded, you should take your car in for a professional flush. The same is true if you’ve mixed different types of coolant in your radiator. But if you’re on schedule for a coolant change and your coolant is free of brown, gunky corrosion (extract a little coolant with a baster to examine it), you can skip the flush procedure and perform a simple drain and refill operation yourself and save money. Here’s how:Start by buying the type of coolant listed in your owner’s manual. If your manual calls for an “extended life” coolant that isn’t available at the auto parts store, buy it from the dealer. Don’t buy a “universal” coolant. Using the wrong coolant can cause premature component failure and void your warranty.Raise and safely support the front end of your car on jack stands. Place a large drain pan under the radiator and remove the radiator cap. If your radiator doesn’t have a cap, remove the pressure cap from the coolant tank. Then open the drain cock and drain the radiator.Drain cocks come in several different styles—screw threads, quarter-turn twist, and quarter turn and pull. Plastic drain cocks become brittle with age and can break easily, especially if you try to unscrew a quarter-turn twist style. So, buy a replacement drain cock at the auto parts store before you begin the job (they only cost a few dollars; return it if you don’t need it).Then remove the lower radiator hose clamp and hose from the engine to drain the rest of the coolant. Use a slip-joint pliers to remove spring-style clamps. If you have trouble accessing or releasing the clamps with a pliers, buy a hose clamp pliers (see photo). Reconnect and clamp the radiator hose and reinstall the drain cock after draining.How to Put Coolant in a CarFollow the coolant manufacturer’s directions for diluting concentrated coolant. Mix the coolant and water thoroughly in a clean bucket. To prevent mineral deposits on internal engine and radiator surfaces, always use distilled water—never tap water. Leave the car raised while you refill the radiator to reduce the possibility of air pockets forming in the engine.Slowly fill the radiator or coolant tank with fresh coolant until the coolant is 1 in. below the neck of the radiator or a few inches below the full mark on the coolant tank. Start the engine and let it run. After the engine warms, you’ll see the coolant level quickly drop in the radiator/coolant tank. That means the thermostat has opened and it’s time to add more coolant to bring the level to the top of the radiator, or to the “HOT” mark on the coolant tank. Check your owner’s manual or service manual to see if your car requires a special air bleeding procedure. Check for leaks, shut off the engine, install the cap, lower the car and go for a spin.CAUTION! Used coolant is toxic waste. Pour it into a screw-cap plastic container and drop it off at a recycling center. Sweet-tasting coolant is irresistible to pets—and poisonous. Just a small amount can be deadly. So soak up any spills with paper towels or rags immediately if you have pets wandering around.Draining and refilling coolant in newer carsChanging your coolant yourself, including buying the air-powered refill tool, will save about $50 on your very first coolant change, and about $100 on each one after that. This procedure works for any cooling system that’s not contaminated with rust or oil. We’ll show you how to check yours and then how to change the coolant.Here’s what you need to change coolant:New coolant (2 gallons)Air-powered refill tool Air compressorHose removal tool Shop manual to locate block drain plugsDrain panAbsorbent paper towelsWrenches and screwdriversStart by checking the condition of your coolant when the engine is cool. Remove the radiator or coolant reservoir cap and examine the coolant color. If it looks rusty (don’t confuse orange coolant with rust), has crud or oil floating on the top, or looks like chocolate milk, call it quits and take it to a pro. You have problems that this procedure won’t solve.If the coolant looks clean, start the job by jacking up the vehicle and supporting it with jack stands. Next, place a large drain pan under the radiator. Loosen the lower radiator hose clamp with pliers (springtype clamp) or screwdriver (worm-drive clamp) and remove the hose (Remove the lower hose.Slip the pointed end of the removal tool all the way into the end of the hose. Then pull it around the radiator neck to break the hose loose. Pull it off quickly and immediately direct the coolant into the drain pan.). If the hose won’t budge, use a hose removal tool to break it loose. Let the radiator and water pump drain completely. Then reattach the lower radiator hose and clamp.Next, locate and remove the block drain plugs (they’re in a different spot on every engine, so refer to a repair manual for the location of yours). Reinstall the block drain plugs and move on to the refilling step.Refilling car with fresh coolant:Insert the air tool into the radiator neck or overflow bottle. Connect the exhaust hose and compressed air line and route the open end of the tool’s exhaust hose into an empty gallon jug or pail. Then open the valve and let the vacuum rise until the needle reaches the edge of the red zone on the gauge. Then fill with coolant (Vacuum-fill the cooling system.Jam the fill tube into the coolant bottle. Then open the valve and let the vacuum suck fresh coolant into the system. Repeat the procedure until the system is full.). The vacuum sucks out any air pockets as it refills the system. When it’s full, just reinstall the radiator or overflow tank caps, remove the jack stands, and go for a spin.
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On the left (A) is a typical flywheel extractor. On the right (B) is a three bolt puller.Special tools are essential for certain jobs on classic motorcycles. One job, in particular, is removing the flywheel from the end of the crankshaft.Typically, the flywheels on motorcycles are held in place by a taper. Both the crankshaft and the flywheel have a machined tapered interface that locks the two components together when a retaining bolt or nut is tightened.To locate a flywheel, a Woodruff key is used. However, it should be noted that the Woodruff key is not intended to stop the flywheel from rotating, but to fix its position for ignition timing purposes.Extractors and PullersRemoving a flywheel from a motorcycle will require the use of an extractor or puller. Many flywheels have a threaded center section for the location of a specific puller (see 'A' in the photograph). Other designs require the use of a bolted plate with a large center bolt that draws the flywheel off as it is tightened (item 'B' in the photograph).Occasionally it is possible to remove a flywheel with a universal extractor such as a three-legged puller. However, small flywheels rarely have sufficient clearance for the legs to pass through.Before the flywheel extractor is located, the retaining center nut or bolt must first be removed. To facilitate the loosening process of the retaining nut, it is necessary to stop the flywheel from rotating. Most manufacturers have a special tool available for this purpose.Note: The temptation to place a large screwdriver (or similar) into the flywheel must be resisted at all costs. The electrical components inside the flywheel will be irreparably damaged by this method.An alternative to a flywheel holding tool when un-tightening the center nut is to use a gloved hand to hold the flywheel while an air powered impact gun is used. However, this method must be approached with caution as the impact gun will try to spin the flywheel.Checking the Thread DirectionBefore attempting to loosen the center nut, the mechanic must ascertain the thread direction; that is, left or right handed threads. Typically, flywheels are designed to rotate in the opposite direction of the threads holding them in place. For instance, a flywheel center nut on the left side of an engine that rotates anti-clockwise when viewed from the left side will have a center nut with standard right-hand threads. (Careful examination of the threads will indicate whether they are left or right handed).With the center nut loosened, it should be backed off until it is level with the end of the shaft, this will support the shaft when the extractor is engaged.Using a proprietary extractor (A), the mechanic must insert it to the full extent of its outer threads. Before tightening the center bolt, when the bolt is tightened against the shaft, the mechanic should tap the extractors bolt with a hammer. The shock from the hammer will separate the tappers and loosen the flywheel.If the flywheel does not come loose the first time the center bolt is tapped, the process should be repeated; for example re-tighten the center bolt, tap with a hammer and so on until the flywheel becomes loose.Seized FlywheelsOccasionally a flywheel will be seized to the crankshaft. This seized condition is due to the flywheel becoming loose at some time and shearing off the Woodruff key. Should the mechanic encounter this problem he may find it necessary to take the components to a specialist engineering or auto-engineering shop to have the flywheel removed. However, he should first check the availability of the components as machining may well destroy them.Before replacing the flywheel it is good practice to lap in the surfaces. This can be accomplished by removing the Woodruff key (ensure there are no high spots around the key's location hole), applying a small amount of fine valve lapping compound and rotating the flywheel on the shaft. Both items must be thoroughly cleaned after this process to remove any dirt or swarf.Replacing the flywheel is simply a case of locating the Woodruff key (leading edge down), and carefully pressing it onto the shaft. With the flywheel located, the center nut should be hand tightened. Next, the flywheel can be tapped onto its tapper with an oversize socket and a dead blow hammer (a lead hammer is ideal for this job). Finally, the center nut must be tightened to its recommended torque.
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