Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
SHIMMING THE STARTER
See Figure 12
Starter noise during cranking and after the engine fires is often a result of too much or too little distance between the starter pinion gear and the flywheel. A high pitched whine during cranking (before the engine fires) can be caused by the pinion and flywheel being too far apart. Likewise, a whine after the engine starts (as the key is released) is often a result of the pinion-flywheel relationship being too close. In both cases, flywheel damage can occur. Shims are available in various sizes to properly adjust the starter on its mount. In order to check and adjust the shims, you will also need a flywheel turning tool, available at most auto parts stores.
If your car's starter emits the above noises, follow the shimming procedure:
Fig. 12: Checking the gap between the starter pinion and flywheel
Disconnect the negative battery cable.
Raise and support the vehicle safely using jackstands.
Remove the torque converter/flywheel cover from the bottom of the bell housing.
Using the flywheel turning tool, turn the flywheel and examine the flywheel teeth. If damage is evident, the flywheel should be replaced.
Most starters are equipped with an access hole in which a small screwdriver or prybar may be inserted to push the starter pinion outward into contact with the flywheel.
Move the starter pinion and clutch assembly so the pinion and flywheel teeth mesh. If necessary, rotate the flywheel so that a pinion tooth is directly in the center of the two flywheel teeth and on the centerline of the two gears, as shown in the accompanying illustration.
Normal pinion-to-flywheel clearance is about 0.01-0.06 in. (0.5-1.5mm).
Check the pinion-to-flywheel clearance by using a 0.020 in. (0.5mm) wire gauge (a spark plug wire gauge may work here, or you can make your own). Make sure you center the pinion tooth between the flywheel teeth and the gauge - NOT in the corners, as you may get a false reading. If the clearance is under this minimum, shim the starter away from the flywheel by adding 0.04 in. (1mm) shims one at a time to the starter mount. Check clearance after adding each shim, but do not use more than 2 shims.
If the clearance is over 0.060 in. (1.5mm), shim the starter towards the flywheel. Broken or severely mangled flywheel teeth are also a good indicator that the clearance here is too great. Shimming the starter towards the flywheel is done by adding shims to the outboard starter mounting pad only. Check the clearance after each shim is added. Add 0.013 in. (0.33mm) shims at this location, one at a time, but do NOT add a total of more than 4 shims.