ENG. RAP NOISE DURING WARM-UP (NOISE GOES AWAY HOT)

Models Affected: EARLY 1990 PRODUCTION 3800 V6

Some owners of 1990 Pontiac vehicles equipped with 3800 V-6 engines may comment on an engine 'rap' or 'diesel' type noise prior to the engine reaching normal operating temperature. The noise will normally appear after one (1) or two (2) minutes of operation and disappear after ten (10) or fifteen (15) minutes of operation. The source of the noise was found to be caused by the addition of a splash oil hole in the pistons. This hole was added to improve high mileage durability and the noise will in no way adversely affect engine operation or durability.

For purposes of customer satisfaction, the noise can be eliminated on 3800 V-6 engines by installing a set of service pistons. GMSPO service pistons do not have the extra splash oil hole drilled.

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.