GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case while in the 4HI range only.

Review the Symptoms - Transfer Case and perform the necessary inspections.

Incorrect fluid level or incorrect fluid

  1. Inspect the transfer case for the correct fluid level. Refer to Transfer Case Fluid Replacement .
  2. Inspect the transfer case for the correct type of fluid.
  3. Flush the transfer case and fill with the correct fluid, if required. Refer to Transfer Case Fluid Replacement .

Input shaft thrust bearings

  1. Inspect for worn or missing input shaft thrust bearings. Refer to Transfer Case Cleaning and Inspection in Transfer Case - Isuzu T150 Unit Repair.
  2. Replace the thrust bearings, as required. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - Isuzu T150 Unit Repair.

2/4 Wheel drive synchronizer assembly

  1. Inspect the synchronizer for the following conditions:
  2. • The synchronizer hub for not being press fit on the rear output shaft splines
    • The synchronizer sleeve to the synchronizer hub for wear
    • The synchronizer sleeve to the drive sprocket engagement teeth
    • Refer to Transfer Case Cleaning and Inspection in Transfer Case - Isuzu T150 Unit Repair.
  3. Replace the synchronizer assembly if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - Isuzu T150 Unit Repair.

Rear output shaft bearing outer retaining ring

  1. Inspect for the following conditions:
  2. • Proper installation of the rear output shaft bearing retaining ring
    • Excessive wear or damaged retaining ring groove in the rear case half
  3. Repair or replace the following components if found faulty:
  4. • Properly install a new rear output shaft bearing outer retaining ring.
    • Replace the rear case half if the retaining ring groove is excessively worn. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - Isuzu T150 Unit Repair.
    • 

Range sleeve

  1. Inspect the range sleeve for the following conditions:
  2. • Worn engagement teeth
    • Worn internal splines
    • Refer to Transfer Case Cleaning and Inspection in Transfer Case - Isuzu T150 Unit Repair.
  3. Replace the range sleeve if worn. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - Isuzu T150 Unit Repair.

Front output shaft yoke

  1. Inspect the front output shaft yoke for the following conditions:
  2. • Yoke flange nut loose
    • Yoke loose fit on the front output shaft
  3. Replace the yoke flange nut if loose. Refer to Front Output Shaft Seal Replacement .
  4. Replace the yoke if the internal splines are worn. Refer to Front Output Shaft Seal Replacement .
  5. Replace the front output shaft if the splines are worn. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - Isuzu T150 Unit Repair.