DIY: Replace Your Timing Belt
What you will need:
Combination Wrenches
A Socket Set
Torque Wrench
A Harmonic Balancer Puller
A Three-jaw Gear Puller
Screwdrivers
Timing Light
Timing Belt Cover Gasket Set
New Timing Belt
Drain Pan
Antifreeze
Jack
Jack stands
(Some models may require special tools)
Before You Start:
Follow these instructions carefully. Read and be sure you understand them before you begin.
Gather together all of your tools and supplies before you begin.
Allow plenty of time to do the job so you don't have to hurry.
Remember that these are general instructions. For more detailed instructions pertaining to your specific vehicle, consult an appropriate repair manual.
Safety is important whenever you're working around machinery. Beware of hot objects, sharp instruments and hazardous materials.
Don't substitute tools unless you're sure you won't compromise either your safety or the performance of your vehicle.
Never work on a vehicle that is only supported by a jack. Use jack stands to support the vehicle while you work. Work on a solid, level surface. Never jack a car up on dirt or grass.
Why Replace Your Timing Belt?
The purpose of a timing belt is to provide a quiet, flexible connection between the camshaft and crankshaft to keep the valves opening and closing in phase with the movement of the pistons.
NOTE: Timing belts are used in two types of engines designated "interference" and "non-interference". If the timing belt breaks on a non-interference design, there is enough clearance between the pistons and valves to prevent damaging contact. An interference design does not have sufficient clearance between those parts and engine damage would result from a broken timing belt. This list notes whether engine damage would result if the belt should break. For vehicles not listed, I recommend replacement at 60,000-mile intervals. Breakage is not the only reason to replace your timing belt. Looseness and wear will allow the timing belt to slip and change valve timing resulting in very poor performance, a no-start condition, or engine damage.
Removal:
Disconnecting the negative battery cable. Insure you have your radio security code (if equipped) and record any preset radio stations and the time on a piece of paper to allow for quick resetting once repairs are made.)
Remove the distributor cap.
Using a wrench on the crankshaft bolt rotate the engine until the timing mark on the crankshaft pulley is aligned with the 0° mark on the timing scale.
Verify the distributor rotor is aligned with the index mark on the distributor housing indicating the rotor is in position to fire the number one cylinder. If not, rotate the engine another full turn.
Remove any components or accessory drive belts that interfere with removing the timing belt cover. This varies by model; consult your service manual to determine which parts need to be removed from your vehicle.
Remove the bolts or screws holding the timing cover in place, and lift the cover off the engine. Some engines have a two-piece timing cover.
Check for proper alignment of the crank and camshaft timing marks.
NOTE: Many engines have a dot or index line on the pulleys or sprockets that must be lined up with corresponding marks on the block, cylinder head, or accessory shaft. On some engines, the index mark on the camshaft sprocket aligns with the parting line of the first camshaft-bearing tower. This is very important if you're replacing a timing belt that has broken. Consult your service manual for the correct alignment procedure for your vehicle and correct any misalignment before installing the new timing belt.
CAUTION: Check the area around the belt for signs of oil or other fluid leakage at seals, cam cover and oil pan. Leaks must be repaired before the new belt is installed.
Loosen the timing belt tensioner.
NOTE: Some vehicles may require a special tool to reach tensioner mounting bolts hidden by components such as motor mounts. Some engines require a special tool to release a spring-loaded timing belt tensioner. However, most engines have a spring-loaded tensioner that can be operated using common tools in the following manner.
Loosen the mounting bolt(s) holding the belt tensioner but do not remove it.
Pry the tensioner away from the belt and then retighten the mounting bolt(s)to hold the tensioner in the loose position.
Examine the tensioner pulley for damage such as dents or cracks.
Spin the tensioner pulley and listen for a rattle or humming noise that would indicate loose or worn bearings. Uneven wear at the rear of the old timing belt could indicate a misalignment between the tension pulley and timing belt due to worn bearings. If any indications of damage or worn bearings are found, replace the tensioner pulley.
With the tension on the timing belt relieved, the belt should slide easily off the sprockets. Timing belts that have been used for a long time may stick in the pulley grooves and require some gentle prying with a screwdriver to release.
Installation:
Caution: Do not rotate the crankshaft or camshaft after removing the timing belt unless it's necessary to correct a timing mark misalignment. This could cause engine damage on an "interference" design engine.
Compare the old and new timing belts. Compare the shape of the belt teeth, the spacing between the teeth, and the width of the belt.
While the belt is off, check the cam and crankshaft sprockets for wear or damage. Replace them if any damage is found.
Slide the new timing belt into position on the sprockets.
CAUTION: Do not force a new timing belt over the sprockets. If the belt won't slide easily check to make sure the belt tensioner is fully released. Timing belts are strong in their correctly installed position only. Do not bend or twist them into any configuration other than the correct one.
Loosen the bolt(s) holding the timing belt tensioner and allow it to contact the belt.
Proper timing belt tension is essential. Adjust the timing belt to the correct tension, following the procedures for your specific vehicle as outlined in your service manual.
After the belt tension is properly adjusted, verify the timing marks on the cam, crank, and accessory sprockets are still in alignment.
With a wrench on the crankshaft pulley, turn the engine over by hand at least two complete revolutions in its normal direction of travel returning to the 0° mark. This will help seat the new belt into place on the sprockets. On "interference" engines, it will also allow you to feel for any hard resistance that may indicate pistons and valves coming into contact.
Verify the position of all timing marks.
Reinstall the timing covers and tighten the attaching bolts or screws securely.
Reinstall the components and drive belts that were removed to gain access to the timing cover.
Reconnect the negative battery cable.
Start the engine and verify proper operation.
That's it, you're done. The average time for this job is from three to four hours. Some vehicles will take somewhat longer, especially for a V-6 engine. By doing it yourself, you'll save anywhere from $250.00 to $400.00. |
匿名
发表于 2010-11-15 16:59:16
