AIR PUMP SQUEAL NORMAL MOD.DISPLACEMENT ENGINES

AIR PUMP SQUEAL SOME AIR PUMPS ON DFI AND V-6 ENGINES HAVE BEEN FOUND TO EMIT A "SQUEALING SOUND" UPON ENGINE COLD STARTS, WHICH LASTS APPROXIMATELY 30 SECONDS OR LESS. THIS CONDITION IS RELATED TO THE DESIGN OF THE PUMP AND SHOULD NOT BE CONSIDERED AS AN INDICATOR COMPONENT REPLACEMENT IS NECESSARY. DO NOT REPLACE PUMPS FOR THIS CONDITION. THE SOUND HAS BEEN EXPERIENCED DURING COLD STARTS AND OCCURS ONLY ONCE AT A PARTICULAR TEMPERATURE. IN COLD WEATHER, THE PLASTIC FAN CONTRACTS SOMEWHAT AND MAY RUB AGAINST THE ALUMINUM BODY OF THE PUMP. THIS CAUSES THE CONTACTING EDGES OF THE FAN TO WEAR DOWN A SMALL AMOUNT AND MAKE A SQUEALING NOISE WHILE DOING SO. IT IS BELIEVED THAT ONCE THE FAN IS "WORN-IN", THE SQUEALING SOUND WILL NOT OCCUR AGAIN UNTIL A SUBSEQUENT COLD START AT A LOWER TEMPERATURE.

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.