For 1990-2009 cars

# GROUP 6A - ENGINE MECHANICAL MISCELLANEOUS ITEMS

1. VI-6-4 EXHAUST MANIFOLDS

CRACKED EXHAUST MANIFOLDS EXPERIENCED ON V8-6-4 EQUIPPED VEHICLES MAY RESULT FROM IMPROPER MANIFOLD INSTALLATION. WHEN INSTALLING THESE EXHAUST MANIFOLDS, A THIN COAT OF MOLY BASED LUBRICANT (GRAPHITE) MUST BE USED. THE CORRECT EXHAUST MANIFOLD INSTALLATION PROCEDURE IS OUTLINED IN THE 1981 SERVICE MANUAL ON PAGE 6A-43 AND IN SERVICEMAN BULLETIN 81-74 (DFI EXHAUST MANIFOLD BOLTS).

2. HT4100 OIL GALLERY PLUG TOOL

REMOVAL OF THE HT4100 VERTICAL OIL GALLERY PLUG (REFER TO THE 1982 SERVICE MANUAL FIGURE 6A8-72, HOLE #109) MAY BE SIMPLIFIED BY USING A SPECIAL TOOL. THIS TOOL CAN BE MADE FROM A STANDARD 3/8" ALLEN WRENCH AS DESCRIBED BELOW:

A. CUT THE SHORT END OFF 1 1/2" FROM THE END.

B. WELD THE TWO PIECES TOGETHER AS SHOWN BELOW.

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.