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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Grand Prix 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Drive Belt Rumbling Diagnosis

Diagnostic Aids

Vibration from the engine operating may cause a body component or another part of the vehicle to make rumbling noise.

The drive belts may have a condition that can not be seen or felt. Sometimes replacing the drive belts may be the only repair for the symptom.

If after replacing the drive belts and completing the diagnostic table, the rumbling is only heard with the drive belts installed, there might be an accessory drive component failure. Varying the load on the accessory drive components may aid in identifying which component is causing the rumbling noise.

Test Description

The numbers below refer to the steps in the diagnostic table.

  1. This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom.

    2.

  2. This test is to verify that the drive belts 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 belts or not. With the drive belts removed the water pump will not operate and the engine may overheat. Also DTCs may set when the engine is operated with the drive belts removed.

    3.

  3. Inspect the drive belts to ensure that the drive belts is not the cause of the noise. Small cracks across the ribs of the drive belts 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.

    4.

  4. Small amounts of pilling is a normal condition and acceptable. When the pilling is severe the drive belts does not have a smooth surface for proper operation.

Step

Action

Yes

No

Notice: Do not use belt dressing on the drive belt. Belt dressing causes the breakdown of the composition of the drive belt. Failure to follow this recommendation will damage the drive belt.

DEFINITION:

    • A low pitch tapping, knocking, or thumping noise heard at or just above idle
    • Heard once per revolution of the drive belts or pulleys
    • Rumbling may be caused from:
       - Pilling, the accumulation of rubber dust that forms small balls (pills) or strings in the drive belts pulley groove.
       - The separation of the drive belts
       - A damaged drive belts

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 noise?

Go to Step 3

Go to Diagnostic Aids

3

  1. Remove the drive belts. Refer to Drive Belt Replacement - Accessory .
  2. Operate the engine for no longer than 30-40 seconds.

Does the rumbling noise still exist?

Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds

Go to Step 4

4

Inspect the drive belts for damage, separation, or sections of missing ribs.

Were any of these conditions found?

Go to Step 7

Go to Step 5

5

Inspect for severe pilling of more than 1/3 of the drive belt groove depth.

Do the drive belt grooves have pilling?

Go to Step 6

Go to Step 7

6
  1. Clean the drive belt pulleys using a suitable wire brush.
  2. Reinstall the drive belts. Refer to Drive Belt Replacement - Accessory .

Did you complete the repair?

Go to Step 8

--

7

Install a new drive belts. Refer to Drive Belt Replacement - Accessory .

Did you complete the replacement?

Go to Step 8

--

8
  1. Clear any codes.
  2. Run the engine in order to verify the repair.

Does the rumbling noise still exist?

--

System OK