ENGINE BUZZING NOISE AT 3,000-4,000 RPM/REPAIR

"BUZZING" SOUND AT 3,000 TO 4,000 RPM

VEHICLES AFFECTED: 1988 N MODEL WITH QUAD 4 (LD2) ENGINE ----------------- Some 1988 "N" models with Quad 4 (LD2) engine built prior to (Pontiac) VIN JC624639, (Buick) VIN JM006657, (Oldsmobile) VIN JM209912, may exhibit an audible "buzz" sound between 3,000 and 4,000 rpm (usually at close to wide open throttle).

The noise is caused by the inlet duct rattling on the air cleaner inlet. The recommended correction is to remove the inlet duct and install a "J" nut, Part No. 11508490, on the top half of the air cleaner inlet with the threaded portion of the "J" nut on the inside (refer to figure) and reinstall the duct over the "J" nut. The "J" nut acts as a spring between the duct and the air cleaner to eliminate the rattle.

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.