DIESEL/LOW ENGINE OIL PRESSURE VALVE LIFTER BORE CLEARANCE

Models Affected: 5.7L (V-8) and 4.3L (V-6) Diesel Engines

Low oil pressure on a diesel engine can be caused by valve lifter clearance due to wear. The wear may occur in the upper end of the bore although the lifter ususally wears more than the bore. To determine if wear has occurred measure the upper end of the lifter in two spots, where it contacts the bore, parallel with the roller and 90 DEG to the roller. Refer to illustration. Wear of .005 to .008 inches is enough to cause low oil pressure and the lifter should be replaced.

Measure the lifter bore in the block. Wear should not exceed .003 inches. If it is necessary to replace the lifters, stone the sharp edges on the bearing shoulder area of the new lifters as shown in illustration, before installation in the lifter bore.

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.