SERPENTINE BELT CHIRP PAINT IN PULLEY GROOVES

MODELS: 1987 M AND G VANS EQUIPPED WITH 4.3L (VIN CODE Z) ENGINES

Some 1987 4.3L "M" and "G" vans equipped with serpentine belt accessory drive may exhibit a chirping sound from the engine compartment. ("Chirp" is a short duration, intermittent, high pitched sound and should not be confused with "squeal", which is continuous in nature.)

The cause of this condition is likely to be paint in the pulley grooves of the serpentine belt or misalignment of the power steering pump pulley. The paint in the belt groove is a result of paint transfer from the A/C compressor pulley to the serpentine belt.

To repair this conditon, perform the following steps:

1. Remove the serpentine belt using procedures in section 6B, Engine Cooling of the service manual.

2. Remove all paint from the A/C compressor pulley grooves. A wire brush mounted on an electric drill can be used to perform this operation.

3. Check alignment of P/S pump pulley hub to the power steering pump shaft and correct as necessary (see Figure No. 1). The power steering pump pulley must be flush, +/-.010 inch, with the shaft for correct alignment.

4. Replace the serpentine belt with a new belt.

NOTICE: BELT DRESSING IS NOT TO BE USED ON THE SERPENTINE BELT, AS IT WILL ONLY AGGRAVATE THE CHIRP CONDITION.

Labor Operation: T7460

Labor Time: .2Hr. Clean A/C pulley and inspect for proper belt alignment.

Add: .2Hr. To loosen and align P/S pulley (include R and R lower shroud on " M", vans).

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.