DRIVE BELT ALIGNMENT DIESEL CRANKSHAFT PULLEY

A crankshaft pulley that is out of alignment on the hub may cause the following conditions.

1. Belt shifting one or more grooves on the crankshaft pulley.

2. Belt coming off of the accessory pulleys.

3. Belt squeaking during engine operation.

4. Loss of the pulley's isolation feature. This results in excessive belt tensioner movement and reduces belt life.

The pulley should have a minimum of 1mm (.040") clearance between the hub and the pulley at the location shown in the Figure below. If the appropriate feeler gage cannot be inserted at this location, the pulley must be replaced. It is not possible to reposition the pulley on the hub.

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.