the only repair for the symptom.
If after replacing the drive belt(s) and completing the diagnostic table, the noise is only heard with the drive belt
(s) installed, there might be an accessory drive component failure. Varying the load on the accessory drive
component(s) may aid in identifying which accessory drive component is causing the rumbling noise.
Test Description
The number(s) below refer to the step(s) in the diagnostic table.
2:
This test is to verify that the symptom is present during diagnosing. Other vehicle components may
cause a similar symptom.
3:
This test is to verify that the drive belt(s) is causing the rumbling. Rumbling may be confused with an
internal engine noise due to the similarity in the description. Remove only one drive belt at a time if the
vehicle has multiple drive belts. Operate the engine for a few seconds, this will verify if the rumbling
noise is related to the drive belt(s) or not. With the drive belt(s) removed the water pump will not operate
and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated
with the drive belt(s) removed.
4:
Inspect the drive belt(s) to ensure that the drive belt(s) is not the cause of the noise. Small cracks across
the ribs of the drive belt(s) will not cause the noise. Belt separation is identified by the plys of the belt
separating, this may be seen at the edge of the belt or felt as a lump in the belt.
5:
Small amounts of pilling is a normal condition and acceptable. When the pilling is severe the drive belt
(s) does not have a smooth surface for proper operation.
Drive Belt Rumbling Diagnosis
Step
Action
Yes
No
DEFINITION:
z
A low pitch tapping, knocking, or thumping noise heard at or just above idle.
z
Heard once per revolution of the drive belt(s) or a pulley(s).
z
Rumbling may be caused from:
{
Pilling, the accumulation of rubber dust that forms small balls (pills) or strings in the drive
belt(s) pulley groove
{
The separation of the drive belt(s)
{
A damaged drive belt(s)
NOTE:
Refer to Belt Dressing Notice in Cautions and Notices.
1
Did you review the Symptoms - Engine
Mechanical diagnostic information, and
perform the necessary inspections?
Go to
Step 2
Go to
Symptoms -
Engine
Mechanical
2
Verify that there is a rumbling noise.
Does the engine make the rumbling
Go to Diagnostic
2004 Chevrolet Corvette
2004 ENGINE PERFORMANCE Engine Mechanical (Introduction) - 5.7L - Corvette
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December-24-07 10:50:10 AM
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