GASKET IN PLACE OF RTV ON ROCKER ARM COVER

SUBJECT: USE OF GASKET IN PLACE OF RTV ON THE 2.5L ENGINE ROCKER ARM COVER

MODELS: 1985-91 S/T LIGHT DUTY TRUCKS AND M VANS WITH 2.5L ENGINES THIS BULLETIN CANCELS AND REPLACES GMC TRUCK SERVICE BULLETIN 89-T-100 DATED SEPTEMBER 1989. ALL COPIES OF 89-T-100 SHOULD BE DISCARDED.

- Two styles of rocker arm cover are available, with and without dimples in the flange area.

- Both silicone/steel and cork/rubber gaskets are available for service applications.

- With the dimpled cover (dimples are located on the flange area), the cork/rubber gasket, P/N 10101791 is preferred; however, RTV may be used.

- With the non-dimpled cover, the silicone/steel gasket, P/N 10124688 is preferred. However, the cork/rubber gasket may be used.

Parts are currently available from GMSPO.

[!] Important ---------

DO NOT USE RTV WITH A NON-DIMPLED COVER. DO NOT USE A SILICONE/STEEL GASKET WITH A DIMPLED COVER.

Even though the gaskets are less sensitive to surface contamination, it is recommended that the sealing surfaces be as clean as possible to assure a reliable seal.

Inspect the rocker arm cover for any bent or distorted flanges. If the flanges are damaged, replace the cover with a new like part.

For the composite cork/rubber gasket, remove the protective paper from the gasket. Place the sticky side of the gasket onto the rocker arm cover.

NOTICE IT IS ESSENTIAL THAT THE PROTECTIVE PAPER BE REMOVED PRIOR 70 GASKET INSTALLATION FOR LEAK PREVENTION

Install the rocker arm cover onto the cylinder head and torque the cover bolts to (5 N-M) 45 in. lb.

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.