Starter Noise Diagnosis. GMC Truck GMC P42 Commercial Chassis 1998

GM Service Manual Online

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC P42 Commercial Chassis 🢒 Engine 🢒 Engine Electrical 🢒 Starter Noise Diagnosis

Table 1:	High-Pitched Whine During Cranking
Table 2:	High-Pitched Whine after the Engine Fires
Table 3:	Loud Whoop Sound after the Engine Fires
Table 4:	Rumble, Growl, or a Knock

High-Pitched Whine During Cranking

Problem	Action
DEFINITION: A high-pitched whine during cranking (before the engine fires), but the engine cranks and fires normally.
The distance is too great between the starter pinion and the flywheel.	Remove the shims at the starter mount. Refer to Starter Pinion Clearance Check .

High-Pitched Whine after the Engine Fires

Problem	Action
DEFINITION: A high-pitched whine, after the engine fires, as the key is being released. The engine cranks and fires normally. This complaint is often diagnosed as starter hang-in or solenoid weak.
The distance is too small between the starter pinion and the flywheel (flywheel runout contributes to the intermittent nature of the problem).	Add shims at the starter mount. Refer to Starter Pinion Clearance Check .

Loud Whoop Sound after the Engine Fires

Problem	Action
DEFINITION: A loud whoop sound after the engine fires, but while the starter is still held engaged. The sound is similar to a siren if the engine is revved while the starter is engaged.
The starter motor clutch is worn.	Remove the starter motor. Refer to Starter Motor Replacement . Check the clutch. Refer to Starter Motor Inspection .

Rumble, Growl, or a Knock

Problem	Action
DEFINITION: A rumble, growl, or a knock (in severe cases) as the starter is coasting down to a stop after starting the engine.
The starter armature is bent or unbalanced.	Remove the starter motor. Refer to Starter Motor Replacement . Check the clutch. Refer to Starter Motor Inspection .