- Low-pitched knocking, detonation, or thumping sounds are heard only at idle speed or slightly above.
- It is heard once per revolution of the drive belt or pulley.
- The rumble may be caused by the following reasons:
- 1. Foreign Particle Adhesion and Embedding - accumulation of rubber dust that forms small balls or threads in the groove of the drive belt pulley
- 2. Drive belt delamination
- 3. Damaged drive belt
Diagnostic information
A rumbling sound may be caused by a body component or another part of the vehicle due to vibration from the running engine.
The drive belt may have properties that cannot be determined by visual inspection. Sometimes replacing the drive belt is enough to eliminate the symptom.
If, after replacing the drive belt and following all of the troubleshooting chart, the rumbling noise is only heard with the drive belt installed, a failure of an accessory drive component may be the cause. Changing the load on the accessory drive component may help identify which component is causing the rumbling noise.
Description of the test
The numbers below refer to the operations in the diagnostic table:
2. This test is performed to check if this symptom is present during diagnosis. Other components of the vehicle may also cause this symptom.
3. This test is done to verify that the rattling noise is actually caused by the drive belt. The rattling noise can be confused with internal engine noise due to the similarity in the description. Running the engine for a few seconds will help determine whether the rattling noise is related to the drive belt or not. Without the drive belt, the water pump will not work and the engine may overheat. Diagnostic trouble codes (DTCs) may also be activated if the engine is running without the drive belt.
4. Carefully inspect the drive belt to make sure it is not the cause of the noise. Small cracks across the ribs of the drive belt will not cause noise. Belt delamination is determined by the bending and twisting of the belt, it can be seen on the side edges of the belt or felt as a bulge on the surface of the belt.
5. A small amount of sticking and inclusions is normal and acceptable. If there is a significant amount of sticking and inclusions, the drive belt no longer has the smooth surface necessary for proper operation.
| Step | Operation | Values | Yes | No |
| 1 |
Have you reviewed the diagnostic information Symptoms - Engine Mechanical and performed the necessary inspections?
|
-
|
Jump to operations 2
|
Go to item Symptoms - Engine Mechanical
|
| 2 |
Check for the presence of a rumbling sound.
Does the engine make a rumbling sound?
|
-
|
Jump to operations 3
|
Go to Diagnostic Information
|
| 3 |
Is the whistling sound still present?
|
-
|
Jump to operations 4
|
|
| 4 |
Inspect the drive belt for damage, delamination, or missing rib sections.
Were any of these conditions detected?
|
-
|
Jump to operations 7
|
Jump to operations 5
|
| 5 |
Inspect for adhesion and inclusions over more than 1/3 of the drive belt groove depth.
Are there any sticking or inclusions in the drive belt grooves?
|
-
|
Jump to operations 6
|
Jump to operations 7
|
| 6 |
Is the renovation complete?
|
-
|
Jump to operations 8
|
-
|
| 7 |
Install a new drive belt. See. Part 1C2, "Engine Mechanical - HFV6 3.2L".
Has the replacement been made?
|
-
|
Jump to operations 8
|
-
|
| 8 |
Is the rumbling sound still present?
|
-
|
-
|
The system is normal
|
[The original text can be found on the website «CHEVYMAN»]