T/CASE NOISE/2- WHEEL DRIVE P/N'S FOR SPROCKET BRGS.. GMC Truck S15 Pickup - 4WD 1985

For 1990-2009 cars

# T/CASE NOISE/2- WHEEL DRIVE P/N'S FOR SPROCKET BRGS.

TRANSFER CASE NOISE IN 2 WHEEL DRIVE

#### VEHICLES AFFECTED: 1985-86 T TRUCKS -----------------

Some 1985 and 1986 T trucks may experience a high pitched (bearing type) whining noise while operating in 2 wheel drive. These vehicles can be checked for this condition by applying firm pressure to the transfer case shift lever and pulling the lever in the direction of 4 High. If this eliminates the whining noise, the condition can be repaired by replacing the two sprocket bearings (See Figure No. 1 - Item 31). This condition is caused by the needle bearings which are inside the sprocket bearing having skewed (turn slightly sideways), which causes them to slide instead of roll.

The above situation was repaired by using a caged bearing on transfer cases dated 4-1-86 and later, which can be identified by, the serial number tag that is located on the rearward side of the transfer case. The serial number is the Date Code. Example Serial Number 4-1-86 (April 1, 1986).

#### Service Parts

P/N 9442178 - Sprocket Bearing/2 Required per vehicle (caged)

#### NOTE: New style sprocket bearings can be identified by vendors name which is stamped on the side, "INA".

#### Service Manual

Refer to the 1986 Unit Repair Manual, Section 7D, for procedures to replace the sprocket bearing.

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.