ENGINE EXCHANGE PROGRAM NEW SERIES OF MARK ENGINES

SUBJECT: ENGINE EXCHANGE PROGRAM

VEHICLES AFFECTED: 1991 TRUCKS WITH 6.OL, 7.OL AND 7.4L ENGINE WITH ALL TRANSMISSIONS

For 1991, GM has introduced a new series of Mark engines. The displacement is the same as the Mark IV engine that they replaced (6.OL, 7.OL and 7.4L). To gain helpful product feedback when an engine must be replaced, and Engine Exchange Program will be in effect until December 31, 1990.

Only valve rocker covers and oil pan can be removed to determine whether engine must be replaced; but before returning engine, valve rocker covers and oil pan must be reinstalled. Complete engines are required.

EXCHANGE PROCEDURE:

Once preliminary diagnosis and/or repairs are made and an exchange unit is deemed necessary, call Technical Assistance Centre (TAC).

- TAC will require VIN and engine serial number. Engine serial number can be found as shown on the attached illustration.

- TAC will arrange with the Woodstock Parts Distribution Centre to directly ship a replacement engine within 24 hours. The replacement engine will be complete except for accessories (i.e., starter, generator, fuel system, etc.).

- TAC will provide a TAC case # for each engine exchange. This number must be recorded on identification card supplied with replacement engine and affixed to replaced engine to be returned. Identification card must be filled out completely.

- Exchange unit must be returned to Woodstock through your local P.D.C. within 7 days in original shipping crate to avoid a chargeback.

EXCHANGE PROCEDURES, CONTINUED:

- Exchange engine must be complete as removed from vehicle. Dealerships returning incomplete units will be subject to being billed for materials missing.

- Shipping instructions will be included with the new engine.

Use applicable Labour Operation Number and Times.taken from the Canadian Labour 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.