CRANKSHAFT SPROCKET KEY SHEAR (VIBR. DAMPERS COMING LOOSE)

MODELS: 1982-89 C/K, RN, P TRUCKS, AND G VANS EQUIPPED WITH 6.2L DIESEL (VIN CODE C, J)

THIS BULLETIN CANCELS AND SUPERSEDES BULLETIN 89-T-26 TO CORRECT A TORQUE SPECIFICATION. ALL COPIES OF 89-T-26 SHOULD BE DISCARDED.

A new hardened washer, P/N 23504011 bas been released for improved clamp load of the crankshaft sprocket to the crankshaft via the crankshaft bolt. Installation torques for the hardened washer have been increased from 190 Nm (140 lbs/ft) to 240 - 250 Nm (180-185 lbs/ft).

Should damper loosening occur, resulting in the crankshaft sprocket shearing the lead alignment key, they should be repaired using the new washer and torque value.

Examine the crankshaft sprocket, and assure before reassembly that there is no damage to the keyway.

During the assembly of the crankshaft sprocket to the crankshaft, GM Goodwrench Thread Locker 272, P/N 12345492 or equivalent should be applied to the crankshaft post for 360 degrees at the rear crankshaft key area only. Thread Locker 272 material should not be applied to the sprocket inside diameter (See illustration).

Parts are currently available from GMSPO.

Use applicable Labor Operation and 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.