Transfer Case Leak Diagnosis

WARNING: This page is about a different variant/trim than selected.

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	Inspect for the correct sealer and the correct amount of sealer on the plugs. Install the plugs correctly. Refer to Transfer Case Fluid Replacement .
Rear output shaft seal leaking	Inspect for the following conditions: Overfilled or improper transfer case fluid Blocked vent Seal improperly installed, worn, or damaged Seal bore damaged or cracked Repair or replace the following components if found faulty: Adjust or replace the transfer case fluid. Refer to Transfer Case Fluid Replacement . Replace the rear case half if the bushing is worn. Refer to TRANSFER CASE DISASSEMBLE and TRANSFER CASE ASSEMBLE in Transfer Case - Overhaul - BW 4476/79 - STS. Replace the rear case half if the seal bore is damaged. Refer to TRANSFER CASE DISASSEMBLE and TRANSFER CASE ASSEMBLE in Transfer Case - Overhaul - BW 4476/79 - STS. Replace the rear output shaft seal. Refer to TRANSFER CASE DISASSEMBLE and TRANSFER CASE ASSEMBLE in Transfer Case - Overhaul - BW 4476/79 - STS.
Front output shaft seal leaking	Inspect for the following conditions: Overfilled or improper transfer case fluid Blocked vent Seal improperly installed, worn, or damaged Seal bore damaged or cracked Repair or replace the following components if found faulty: 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 - Overhaul - BW 4476/79 - STS. Replace the front output shaft seal. Refer to TRANSFER CASE DISASSEMBLE and TRANSFER CASE ASSEMBLE in Transfer Case - Overhaul - BW 4476/79 - STS.
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	Inspect for the following conditions: Loose mounting fasteners Gasket or sealant faulty The transfer case input shaft seal leaking Damaged O-ring on vent Repair or replace the following components if found faulty: Replace the transfer case input shaft seal. Refer to Transfer Case 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. Repair or replace the following components if found faulty: 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 Extension Housing and Seal 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 - Overhaul - BW 4476/79 - STS.
Case leaking	Inspect for a cracked case or case porosity. Replace the faulty case half. Refer to TRANSFER CASE DISASSEMBLE and TRANSFER CASE ASSEMBLE in Transfer Case - Overhaul - BW 4476/79 - STS.