DRIVE BELT RUMBLING AND VIBRATION DIAGNOSIS
Diagnostic Aids
The accessory drive components can have an affect on engine vibration. Vibration from the
engine operating may cause a body component or another part of the vehicle to make rumbling
noise. Vibration can be caused by, but not limited to the air conditioning (A/C) system over
charged, the power steering system restricted or the incorrect fluid, or an extra load on the
generator. To help identify an intermittent or an improper condition, vary the loads on the
accessory drive components.
The drive belt may have a rumbling condition that can not be seen or felt. Sometimes replacing
the drive belt may be the only repair for the symptom.
If replacing the drive belt, completing the diagnostic table, and the noise is only heard when the
drive belts are installed, there might be an accessory drive component with a failure. Varying the
load on the different accessory drive components may aid in identifying which component is
causing the rumbling noise.
Test Description
The numbers below refer to the step numbers on 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 one of the drive belts is causing the rumbling noise or vibration.
Rumbling noise 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.
17
Inspect for the correct pulley size.
Did you find and correct the condition?
Go to Step 20
Go to Diagnostic
Aids
18
Replace the bent pulley.
Did you complete the repair?
Go to Step 20
Go to Step 19
19
Replace the drive belt. Refer to Drive Belt
Replacement - Accessory or Air
Conditioning Compressor Belt
Replacement .
Did you complete the repair?
Go to Step 20
Go to Diagnostic
Aids
20
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 3
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Mechanical - 4.3L - Sierra & Silverado