CYLINDER HEAD GASKET LEAK REPAIR PROCEDURES- DIESEL

Questions regarding recessed or protruding prechambers in the cylinder head have been raised. Dealer Technical Bulletin 81-T-40 states that prechambers must not be recessed into the cylinder head or protrude out of the cylinder head by more than .004". This measurement should be made on both sides of the prechamber where the gasket sealing ring crosses the prechamber and cylinder head. It does not matter if the prechamber is cocked a little bit so that you get a different measurement on each side. Both sides, however, must be within the tolerance.

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.