OIL PRESSURE LIGHT ON AT IDLE LOSS OF OIL PRESSURE AT IDLE

VEHICLES AFFECTED: 1985-86 Engines (Engine Code L) and 1986 Enqines (Engine Codes B and 3)

If a condition of no oil pressure at idle occurs on one of the above engines, the oil pressure relief valve may be sticking in the bore in the engine front cover. To check for freeness, remove the oil filter adapter assembly. Spring tension behind the valve should cause it to pop out of the bore once the adapter assembly is removed. If it does not, it is sticking or binding and needs to be freed up.

Simply forcing the valve in board as far as possible several times against the spring pressure behind it will usually free it up. To insure continued freeness of the valve it should be removed and a very small chamfer should be formed at the outer edge of the outside of the valve at the stepped end using crocus cloth or extremely fine emery paper. (See illustration).

The first land of the bore inside the timing chain cover should also be checked for smoothness. A thorough cleaning of the bore should be performed to remove all foreign material before reassembly.

Additionally, the oil filter adapter gasket may have a tear area in the gasket surface that covers, an oil channel port in the timing cover. Pieces of the gasket may stick the oil pressure relief valve. To correct this condition, clean cover oil passages of any gasket material and replace gasket with a new one, Part number 25529916. The new gasket has an irregular shaped hole to avoid exposure of gasket material to the oil channel.

Use applicable labour time and operation number.

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.