DIAGNOSIS OF NOISE FROM REAR MAIN SEAL

VEHICLES AFFECTED: 1987 "J" WITH LL8 L-4 ENGINW (VIN CODE 1)

A chirp or squeal at the rear main seal area that goes away when oil is sprayed into the area may be encountered. This may be due to improper engine ventilation producing an internal vacuum depression drawing air past the seal.

If the noise symptom disappears when the dipstick cap or oil fill cap is removed, preventing sump depression, then check the fresh air feed hole in the air inlet rubber duct for blockage where it connects to the rocker cover. Cut out any blockage in the inlet rubber duct feed hole to eliminate the noise.

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.