INFO ON AVAILABLE DIAGNOSTIC AIDS 4.5L 4.9L DRIVE NOISE

SUBJECT: 1990-1992 4.5L, 4.9L ACCESSORY DRIVE NOISE DIAGNOSIS

Many dealers have had great success diagnosing engine and accessory drive noises using a series of special length serpentine drive belts which allow the engine to be operated temporarily with each of the driven accessories inoperative. A kit containing one each of these special length belts is available from Kent-Moore under J-36312 for all 1985-1989 engines. (These engines incorporate an AIR pump in the accessory drive.) Now available is a similar set of belts for 1990-1992 engines without the AIR pump. Dealers may order this kit J-39429 using the attached order form.

We believe this source and their equipment to be reliable. There may be additional manufacturers of such equipment, however, General Motors does not endorse, indicate any preference for, or assume all responsibility for the products or equipment from these firms or for any such items which may be available from other sources.

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.