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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 Driveline/Axle 🢒 Transfer Case - BW 4476/79 🢒 Transfer Case Leak Diagnosis

Cause

Correction

DEFINITION: A visible indication of an external fluid leak from the transfer case.

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

Drain plug or fill plug leak
  1. Inspect for the correct sealer and the correct amount of sealer on the plugs.
  2. Install the plugs correctly. Refer to Transfer Case Fluid Replacement .

Rear output shaft seal leaking
  1. Inspect for the following conditions:
    2. • Overfilled or improper transfer case fluid
    • Blocked vent
    • Seal improperly installed, worn, or damaged
    • Seal bore damaged or cracked
  2. Repair or replace the following components if found faulty:
    3. • Adjust or replace the transfer case fluid. Refer to Transfer Case Fluid Replacement .
    • Replace the rear case half if the seal bore is damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - BW 4476/79 Unit Repair.
    • Replace the rear output shaft seal. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - BW 4476/79 Unit Repair.

Front output shaft seal leaking
  1. Inspect for the following conditions:
    2. • Overfilled or improper transfer case fluid
    • Blocked vent
    • Seal improperly installed, worn, or damaged
    • Seal bore damaged or cracked
  2. Repair or replace the following components if found faulty:
    3. • Adjust or replace the transfer case fluid. Refer to Transfer Case Fluid Replacement .
    • Replace the front case half if the seal bore is damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - BW 4476/79 Unit Repair.
    • Replace the front output shaft seal. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - BW 4476/79 Unit Repair.

Leaking at the vent

    • Leaking vent or input seal will be noticed from a weep hole between the adapter and the transfer case.
    • Transfer case overfilled
        Inspect for the correct transfer case fluid level. Refer to Transfer Case Fluid Replacement .
    • Damaged O-ring on vent
    • Transmission output shaft seal leak will be noticed from a weep hole between the adapter and the transfer case.

Transfer case-to-adapter leak
  1. Inspect for the following conditions:
    2. • Loose mounting fasteners
    • Gasket or sealant faulty
    • The transfer case input shaft seal leaking
    • Damaged O-ring on vent
  2. Repair or replace the following components if found faulty:
    3. • Replace the transfer case input shaft seal. Refer to Input Shaft Seal Replacement .
    • Inspect for the following:
       - Seal improperly installed, worn, or damaged
       - Seal bore damaged or cracked
       - Input shaft seal surface worn, grooved, or damaged
    • Repair or replace the loose fasteners.
    • Replace the transfer case gasket or sealer.
  3. Repair or replace the following components if found faulty:
    4. • Leaking transmission output seal
    • Remove transfer case. Refer to Transfer Case Assembly Replacement .
    • Leaking adapter gasket and seal
    • Replace adapter gasket and seal. Refer to Case Extension and Gasket Replacement in Automatic Transmission - 5L40-E/5L50-E.

Front case half-to-rear case half seam leak

Disassemble and seal the case halves. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - BW 4476/79 Unit Repair.

Case leaking
  1. Inspect for a cracked case or case porosity.
  2. Replace the faulty case half. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - BW 4476/79 Unit Repair.