REDUCED PWR. STEER. ASST. WHEN COLD (REPL. W/NEW VALVE ASSY.)

SUBJECT: REDUCED POWER STEERING ASSIST WHEN COLD (REPLACE WITH NEW VALVE ASSEMBLY)

MODELS: 1988-92 C/K TRUCKS

THIS BULLETIN CANCELS AND REPLACES GMC TRUCK SERVICE BULLETIN 92-3B-146, DATED DECEMBER 1992 TO CHANGE THE PARTS INFORMATION. ALL COPIES OF 92-3B-146 SHOULD BE DESTROYED.

Owners of some 1988-92 C/K trucks equipped with power steering may comment that during a cold start condition there is reduced power steering assist.

This condition is caused by the current fluoroelastomer O-rings not providing enough spring force to engage the teflon valve rings under all dimensional stack conditions. This condition occurs during vehicle cold starts, after the vehicle has been subjected to high temperature operating conditions.

To correct this condition the steering gear valve assembly should be replaced with a new valve assembly that features new hydrogenated nitrile base rubber valve body O-rings to eliminate potential for lack of power steering assist during cold starts. The 1993 C/K production steering gears include the new valve assembly.

SERVICE PROCEDURE

Tools Required :

J 7624 Adjustable Spanner Wrench

J 4245 Snap Ring Pliers

J 8524-1 Adjuster Plug Bearing Installer

J 7079-2 Driver

J 29810 Seal Protector

J 7754-01 0-25 lbs. in. torque wrench

Remove (Figure 1)

1. Steering gear from the vehicle.

- Refer to section 3B1 of the appropriate C/K service manual for complete removal instructions.

2. Adjuster plug locknut (245).

3. Adjuster plug assembly (240) using J 7624.

- Retaining ring (244) using J 4245 or equivalent snap ring pliers.

- Washer (243).

- Stub shaft oil seal (242).

- Adjuster plug seal (239)

4. Steering valve assembly (250) and stub shaft O-ring seal (249).

Important

Do not remove the worm shaft (248) and thrust bearing assembly (246, 247) when removing the steering valve assembly. Removing the worm shaft will result in one or more balls (213) dropping out of the steering worm circuit. Loss of any balls in the circuit will require a complete rebuilding of the steering rack and worm assembly.

Install (Figure 1)

1. New stub shaft O-ring seal (249).

Important

The valve body assembly, rings and all seals should be lubricated with power steering fluid before assembly.

2. New steering valve assembly (250) (Figure 2).

Important

Note that pin (A) on the worm gear (248) lines up with slot (B) in the steering valve assembly (250).

3. Stub shaft oil seal (242) to adjuster plug (240) using J 8524-1 and J 7079-2.

- Be sure adjuster plug bearing (241) is seat ed in adjuster plug (240). Use J 8524-1 and J 7079-2 if necessary.

4. New adjuster plug seal (239) to the adjuster plug assembly (240).

5. Adjuster plug assembly (240) using J 7624.

- Protect the stub shaft oil seal (242) from damage by placing J 29810 over the splined end of stub shaft (251) before installing the adjuster plug (240).

- Adjust thrust bearing preload (Figure 3).

- After adjusting thrust bearing preload, check the turning torque of the stub shaft (251) using J 7754-01 (0-25 lbs. in. torque wrench) and a 12-point socket. Combined torque reading (stub shaft bearing preload and pitman shaft preload) for the gear assembly must not exceed 20 lbs. in. (2.26 N.m). If this reading is exceeded, repeat the adjustment procedure. If necessary, refer to section 3B1A-4 (Unit Repair Manual) for pitman shaft preload. Adjustment of 5-10 lbs. in. (0.57-1.13 N-m.) is desired. If this reading is not obtained, repeat the adjustment procedure.

6. Washer (243).

7. Retaining ring (244).

Important

The retainer projections must not extend beyond the washer (243) when the retaining ring (244) is seated. The washer must be free to rotate.

8. Adjuster plug locknut (245).

9. Steering gear to vehicle.

- Refer to section 3B1 of the appropriate C/K service manual for complete installation and system bleed procedure instructions.

SERVICE PARTS INFORMATION

P/N Description Year Applications --- ----------- ---- ------------ 26036096 Valve Assembly, 1992 C1 K1 Suburban Steering Gear L05 Engines

26036095 Valve Assembly, 1988-92 All Other Steering Gear C/K Models

26010275 Seal Kit, All Models Adjuster Plug

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

Labor Operation Model Labor Time --------- ----- ---------- T7176 C 1.2 hrs.

T7176 K 1.3 hrs.

NOTE: Labor 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.