DRIVELINE MOAN, DROAN OR VIB. AT 2800 RPM-INTERIOR VIBRATES. GMC Truck S15 Pickup - 2WD 1991

For 1990-2009 cars

# DRIVELINE MOAN, DROAN OR VIB. AT 2800 RPM-INTERIOR VIBRATES

#### SUBJECT: DRIVELINE MOAN DROAN RESONANCE VIBRATION AT 2800 RPM - INSTALL DAMPER KIT

#### VEHICLES AFFECTED: 84-86, 89-91 'S' PICKUP W/BORG-WARNER M/T AND 2.5L

Some 1984-86 and 1989-91 S pickup trucks may experience a condition described as driveline moan, drone, resonance or vibration. This condition usually occurs at approximately 2800 rpm when the cab and/or interior panels may buzz or vibrate.

Service damper kits are available for installation on these S pickup trucks. These dampers will significantly reduce vibrations in the 2800 rpm range. Refer to the SERVICE PROCEDURE section for the specific action required for the model years listed.

#### VEHICLES INVOLVED

1984-1986 and 1989-1991 S pickup trucks (models S10603, S10653, S10803) equipped with 2.5L engine and Borg-Warner 4 or 5 speed manual transmission.

#### SERVICE PROCEDURE

1984 - 1986 S pickup trucks:

These vehicles can be repaired using the damper P/N 14073312 and method described in Product Service Bulletin 83-7-127 This bulletin calls for a transmission mount change on some models. If the transmission mount features the dual captive stud mounting, the transmission mount does not require replacement.

1989 - 1991 S pickup trucks:

Service damper kit P/N 15674891 containing a damper, new transmission extension housing with damper mounting bosses and fasteners should be installed.

#### REMOVE-(Figure 1)

1. Transmission from vehicle.

- Refer to Section 7B of the appropriate S/T Service Manual for complete transmission removal procedure.

- Drain transmission before removal.

#### IMPORTANT: Do not let the transmission hang from the clutch.

2. Speed sensor from extension housing.

3. Roll pin (663) from offset lever.

- Place offset lever (659) in 3-4 position of neutral.

- Use a pin punch and hammer to drive the roll pin (663) through the shift shaft as shown in Figure 2.

#### IMPORTANT: Removal of the shift roll pin from the offset lever must be done with the offset lever in the 3-4 position of neutral or the pin may be driven into the detent/guide plate, damaging the plate and preventing further disassembly of the transmission.

4. Extension housing (610) from transmission.

- Remove the eight bolts holding the extension housing to the case.

- Separate the extension housing from the transmission case and slide rearward. The offset lever (659) will also separate from the shift shaft.

#### IMPORTANT: The offset lever is engaged into the extension housing and cannot be removed when the extension housing is mounted to the transmission.

- Detent ball (662) and detent spring (660) from the detent/guide plate.

- Clean old sealer from extension housing mating surface.

5. Roll pin (663) from the offset lever (659).

#### IMPORTANT: Failure to remove the roll pin from the offset lever may result in driving the pin into the detent/guide plate during assembly making future disassembly difficult.

INSTALL (Figure 1)

1. New extension housing (610).

- Apply a 3mm (1/8-inch) diameter bead of RTV sealant on the sealing surface of the extension housing.

- Lubricate the detent/guide plate with lithium grease and install the detent ball (662) in the 3-4 neutral position of the detent plate.

- Place the offset lever (659) and detent spring (660) over the detent ball (662) .

- Slide the extension housing against the transmission case while guiding the offset lever (659) over the shift shaft.

2. Extension to case bolts.

- Apply sealer to threads of top 2 bolts.

- Tighten bolts to 30 N.m (25 lbs. ft.).

3. Offset lever roll pin (663).

4. Speed sensor.

5. Transmission.

- Refer to Section 7B of the appropriate S/T Service Manual for complete transmission installation procedure.

- Refill transmission with fluid.

6. Damper to transmission as shown in Figure 3.

-Be sure damper is installed facing in the proper direction.

-Tighten bolts (2) to 45 N.m (35 ft.lbs.).

-Tighten weight bolt (5) to 100 N.m (75 ft.lbs.).

#### SERVICE PARTS INFORMATION

Part Number Description ----------- ------------------------------- 15674891 Damper Kit, Driveline Vibration

#### WARRANTY INFORMATION

For vehicle repaired under warranty use:

Labour Operation: T7156 Labour Time: 2.6 hrs

#### NOTE: Labour Operation is coded to base vehicle coverage in the warranty system.

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.