VEHICLES AFFECTED: 1982-93 "B,D,F,Y" MODELS, "C/K, R/V, SIT" TRUCKS AND "G,M,L" VAN WITH 4L60 TRANSMISSION
Some 1982-1993 vehicles equipped with a HYDRA-MATIC 4L60 transmission may have a buzzing noise coming from the transmission when the vehicle is at idle. The buzzing noise may be noticed more when the vehicle is in reverse at idle.
The buzzing noise may be a result of pressure regulator valve oscillating due to oil pressure instability at lower idle RPM.
A new pressure regulator valve (Illustration # 218) has been made which will improve the oil pressure stability at lower RPM.
SERVICE PARTS INFORMATION:
Description Part Number Valve, Pressure Regulator 8684048 (Illustration # 218)
For vehicles repaired under warranty use: Labour Operation: K6550 Valve, Pressure Regulator--R&R or Replace
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.