BACK PRESSURE EGR VALVES IDENTIFICATION METHOD

VEHICLES AFFECTED: ALL 1983 VEHICLES EQUIPPED WITH THE 3.0 LITER V-6 (VIN CODE E), 3.8 LITER V-6 (VIN CODE A), OR 4.1 LITER V6 (VIN CODE 4) ENGINES INTERNAL REVISIONS HAVE BEEN MADE TO BACKPRESSURE EGR VALVES USED ON THESE ENGINES. IT IS NO LONGER POSSIBLE TO IDENTIFY A POSITIVE OR NEGATIVE TYPE VALVE BY VISUAL INSPECTION OF THE DIAPHRAM PLATE, AS HAS BEEN DONE IN THE PAST. THE NEW EGR VALVE HAS THE LETTER 'N' (FOR NEGATIVE BACKPRESSURE), OR 'P' (FOR POSITIVE BACKPRESSURE), ON THE LINE BELOW THE MODEL IDENTIFICATION NUMBER, AS SHOWN. THE PRESENT SHOP MANUAL SERVICE PROCEDURE HAS NOT BEEN CHANGED.

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.