Diagnostic Aids
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect the flywheel ring gear for damage or unusual wear.
- Shim the starter if applicable.
- In order to add pinion to ring gear clearance a full size shim must be used. Do not shim only 1 starter mounting bolt. There are 3 shims available in different shapes for clearance. All are 1 mm (.039 in) thick.
Starter Motor Noise Diagnosis
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you perform the Engine Electrical Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Engine Electrical |
| 2 | Start the engine. Does the starter operate normally? |
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Start the engine while listening to the starter motor turn. Is there a loud "whoop" which may sound like a siren if the engine is revved while the starter is engaged after the engine starts, but while the starter is still held in the engaged position? |
Go to Step 6 | Go to Step 4 |
| 4 | Do you hear a "rumble", a "growl", or, in some cases, a "knock" as the starter is coasting down to a stop after starting the engine? | Go to Step 7 | Go to Step 5 |
| 5 | This is often diagnosed as a starter drive gear hang-in or a weak solenoid. When the engine is cranked, do you hear a high-pitched whine after the engine cranks and starts normally? |
Go to Step 8 | Go to Step 7 |
| 6 | Inspect the flywheel ring gear for the following:
Is the flywheel bent, or does it have damaged teeth? |
Go to Step 9 | Go to Step 10 |
| 7 |
|
Go to Step 10 | Go to Step 9 |
| 8 | Shim the starter motor away from the flywheel by adding shims between the starter motor and the engine block one at a time. Flywheel runout may make this noise appear to be intermittent. Did you complete the repair? |
Go to Step 11 | - |
| 9 | Replace the flywheel. Refer to Engine Flywheel Replacement
in Engine Mechanical 4.3 L, Engine Flywheel Replacement
in Engine Mechanical 4.8 L, 5.3 L and 6.0 L, Engine Flywheel Replacement - Automatic Transmission
in Engine Mechanical 6.6 L, Engine Flywheel Replacement - Manual Transmission
in Engine Mechanical 6.6 L or Engine Flywheel Replacement
in Engine Mechanical 8.1 L. Did you complete the replacement? |
Go to Step 11 | - |
| 10 | Replace the starter motor. Refer to Starter Motor Replacement (4.3L Engine)
or Starter Motor Replacement (4.8L, 5.3L, and 6.0L Engines)
or Starter Motor Replacement (6.6L (LB7) Engine)
or Starter Motor Replacement (6.6L (LLY) Engine)
or Starter Motor Replacement (8.1L Engine)
. Did you complete the replacement? |
Go to Step 11 | - |
| 11 | Operate the system in order to verify the repair. Did you correct the condition? |
System OK | Go to Step 3 |