To correct starter motor noise during starting, use the following procedure:
Checks | Action |
|---|---|
Inspect for a high-pitched whine during cranking before the engine fires. The engine cranks and fires properly. | The distance is too great between the starter pinion and the flywheel. Shimming the starter toward the flywheel is required. |
Inspect for a high-pitched whine after the engine fires, as the key is being released. The engine cranks and fires properly. This intermittent complaint is often diagnosed as starter hang-in or solenoid weak. | The distance is too small between the starter pinion and the flywheel. Shimming the starter away from the flywheel is required. |
Inspect for a loud whoop after the engine fires but while the starter is still held engaged. The sound is like a siren if the engine is revved while the starter is engaged. | The most probable cause is a defective clutch. A new clutch will often correct this problem. |
Inspect for a rumble, a growl, or, in severe cases, a knock as the starter is coasting down to a stop after starting the engine. | The most probable cause is a bent or an unbalanced starter armature. A new armature will often correct this problem. |
If the complaint is noise, correction can be achieved by proper shimming as follows:
- Check for a bent or a worn flywheel.
- Start the engine and carefully touch the outside diameter of the rotating flywheel ring gear with chalk or a crayon to show the high point of the tooth runout. Turn OFF the engine and rotate the flywheel so that the marked teeth are in the area of the starter pinion gear.
- Disconnect the negative battery cable in order to prevent the cranking of the engine.
- Check the pinion-to-flywheel clearance by using a wire gage of 0.5 mm (0.02 inch) minimum thickness or diameter. Center a pinion tooth between two flywheel teeth and the gage. Do not gage in the corners where a misleading larger dimension may be observed. If the clearance is under this minimum, shim the starter away from the flywheel.
- If the clearance approaches 1.5 mm (0.06 inch) or more, shim the starter toward the flywheel. This condition is generally the cause of broken flywheel teeth or the starter housing. Shim the starter toward the flywheel by shimming only the outboard starter mounting pad. A shim of 0.40 mm (0.016 inch) thickness at this location will decrease the clearance by approximately 0.30 mm (0.012 inch). If normal starter shims are not available, plain washers or other suitable material may be used as shims.
