Supercharger Noise - keywords compartment engine speed

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may comment about a noise coming from the engine compartment that gets louder as engine speed increases. Upon inspection you may find that noise appears to be coming from the supercharger assembly.

1. Verify that the oil level in the supercharger assembly is full. If additional supercharger oil is needed, add part number 12345982 as necessary. See SI for additional information.
2. Verify that the noise is NOT the usual "whine" type sound that is typically heard on a supercharged engine.
3. If possible, compare the noise level to that on another "Supercharged" vehicle.
4. Verify that the noise is coming from the supercharger by removing the drive belt. If the noise is still present it probably is not coming from the supercharger.
5. If the noise returns after the belt is reinstalled, apply a light spray of soapy water on the belt. If the noise goes away, check the supercharger belt and the alignment of the supercharger drive belt pulleys.

Metro Detroit Dealers:

Engineering is looking for a vehicle in the "Metro Detroit" (Southeast Michigan) area that exhibits the condition. Dealers in the "Metro Detroit" area that have a vehicle that exhibits the condition should contact Jim Kelly at (586) 492-5612. He will assist in making arrangements for Engineering to review the vehicle at your Metro Detroit area location.

All Other Dealers:

As soon as the root cause of this condition is identified and an approved repair is developed, this document will be updated and/or a bulletin published. In the meantime do not attempt to repair the condition by replacing the supercharger or related parts. Advise the vehicle owner that GM is working to find the cause of the noise and that you will contact them when a repair procedure has been made available.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.