EXCESSIVE OIL CONSUMPTION INSPECT INTAKE VALVE SEALS

SUBJECT: EXCESSIVE OIL CONSUMPTION (INSPECT INTAKE VALVE STEM SEALS)

MODELS: 1988 S/T TRUCKS AND M VANS (WITH 2.5L ENGINES)

Customer comments may be received regarding excessive engine oil consumption. Light blue-colored exhaust smoke may or may not be evident in these cases due to the catalytic converter's exhaust gas processing.

This oil consumption condition may be caused by one or more damaged intake valve stem seals.

NOTE: It is recommended that intake valve stem seal inspection be performed first in diagnosing reported cases of excessive engine oil consumption.

An inspection of the intake valve stem seal of any cylinder will reveal if the seal is in fact damaged. The damaged seal(s) can be identified by a cutout section on the top portion of the seal, see Figure 1. Valve spring removal is required to properly inspect the seal. If a seal is identified as damaged, all intake valve stem seals must be replaced with P/N 10042875. Refer to Section 6Al of the Service Manual for details on seal servicing.

Parts are currently available from GMSPO.

If the intake valve stem seal inspection for all cylinders does not reveal any damaged seals, then the cause of the excessive oil consumption is in some other area of the engine.

Use applicable labor operation and time per the Labor Time Guide.

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.