INFO. ON HIGH OIL PRESSURE READING AT START UP

Subject: HIGH OIL PRESSURE READING AT START-UP

Model and Year: 1992-93 LIGHT DUTY TRUCKS WITH 4.3L, 5.OL, AND 5.7L ENGINES

Some 1992 and 1993 Chevrolet Light Duty Trucks with oil pressure gages built after 6/15/92 may exhibit high oil pressure readings at start up, especially when cold.

Engines produced after 6/15/92 were built with an enhanced oil pump capable of producing approximately 1 0 psi more pressure than the previous pump. This may cause the gage to temporarily read as high as 60 psi during start up. The length of time the oil pressure stays high will depend on oil viscosity, engine temperature, and ambient temperature.

This condition will not cause any ill effects on the engine or gage and unless there are other symptoms to indicate an oil pressure or gage problem such as very low pressure after warm up, rapid fluctuation, engine noise etc. no repairs should be attempted. Replacing the oil pump or gage system parts will not be effective.

Build date of the engine can be verified by the engine code. The location of this code is illustrated in section OA of the appropriate service manual. The engine code is 8 positions long with an alpha plant designator in the first position, followed in the next four positions by the month and day; for example T0615xxx would indicate that this engine was built in Tonawanda on June 15th and, therefore, has the enhanced oil pump. The plant code is insignificant because all 4.3L, 5.OL, and 5.7L plants began using the enhanced oil pump on the same day.

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.