DIESEL CLUTCH INTERFERENCE HARD SHIFTING AND GEAR NOISE

MODELS: 1982 AND SOME 1983 C, K, AND P TRUCKS EQUIPPED WITH THE 6.2L DIESEL ENGINE (RPO LL4) AND THE 117 MM. 4-SPEED MANUAL TRANSMISSION (RPO M20)

1982 and some 1983 C, K, and P trucks equipped with the 6.2L diesel and 4-speed manual transmission may experience any or all of the following conditions:

Hard Shifting

Transmission Bearing and/or Gear Noise

Improper Clutch Operation

These conditions may be caused by a transmission to engine misalignment. The misalignment can be caused by the top cover of the transmission protruding beyond the front face of the transmission (see Figure No. 1).

If a vehicle exhibits any of the conditions listed above, the following procedure should be followed:

1. Raise the vehicle. Using a .127 mm. (.005 in.) shim, check for gaps between the transmission and clutch housing.

2. If a gap or separation is noted, check for clearance between the top cover and the clutch housing.

If an interference exists, it will be necessary to remove the transmission top cover and grind away the excessive material. The following steps should be performed to acquire the proper clearances. It will not be necessary to remove the transmission assembly from the vehicle.

1. Loosen, DO NOT REMOVE, four transmission to clutch housing attaching bolts.

2. Remove the transmission top cover as outlined in the Light Duty Truck Service Manual (X- 8232: Section 7B4-6 or X-8341: 117 mm. Manual Transmission, p. 6).

3. Grind away the excess material from the forward side of the top cover to allow a proper transmission to clutch housing fit.

NOTICE: All ground edges are to be deburred.

4. Wash the cover with a recommended solvent to remove metal contaminants.

5. Torque the four transmission to clutch housing attaching bolts before installing the top cover. Bolt torque is 100 N.m. (75 ft. lbs.).

6. Install the reworked top cover and a new gasket. Torque attaching bolts to 27 N.m. (20 ft. lbs.). If the top cover has proper clearances, there will not be interference with cover alignment or bolt installation.

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.