VALVE TAPPET AND INABILITY TO SET VALVE LASH (VALVE TRAIN NOISE OR TAPPET NOISE) CHECK ROCKER ARMS Revised to clarify the statement on rocker arm replacement.
If the engine build date is from T0505xxx to T0512xxx, then the rocker arms should be checked. The engine build date is located on top-rear surface of cylinder case on exhaust side of engine -- NO PARTS NEED TO BE REMOVED TO READ THE NUMBER. The rocker arms that have excessive valve lash and have the correct valve rocker arm nut torque should be replaced with a new service part.
Engines that display valve train noise and are outside THIS ENGINE BUILD DATE GROUP should be examined in other areas of the valve train for cause of the noise.
Use applicable labor operation code and labor time.
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.