Transfer Case Leak Diagnosis

Fluorescent Dye Method

1. Add GE 28431-6  Fluorescent dye to the transmission or transfer case to determine the source of the leak.
2. Operate the vehicle.
3. Inspect for the presence of dye within the oil leak using the GE 28428-E  High Intensity Black Light Kit. A presence or non-presence of dye within the oil leak will indicate which component is the source of the leak.

Powder Method

CAUTION:

Do not clean using brake cleaner or other reactive solvents as these solvents can damage rubber gaskets, seals and bushings.

1. Thoroughly clean the suspected leak area using a rag.
2. Apply an aerosol type leak tracing powder to the suspected leak area.
   NOTE:

   Do not drive the vehicle on the freeway as this will splatter oil inhibiting leak diagnosis.

3. Operate the vehicle for 15-20 minutes under city driving conditions until normal operating temperatures are reached.
4. Shut OFF the engine.
5. Inspect the suspected leak area.
6. Trace the leak path through the powder in order to find the source of the leak.

1. Inspect for a transfer case for an overfill condition
   1. Add j-28431-6  Fluorescent Dye to the transmission to determine if the transfer case input shaft oil seal is the cause of the overfill.
   2. Operate the vehicle
   3. Inspect the transfer case fluid for presence of dye within the oil using the j-28428-E  High Intensity Black Light Kit.
2. If fluorescent dye is present within the transfer case fluid, replace the transfer case input shaft oil seal. Refer to Input Shaft Seal Replacement .

1. Inspect for a restricted vent hose assembly. Repair as required.
2. Add J-28431-6  Fluorescent Dye to the transmission to determine the source of the leak.
3. Operate the vehicle
4. Inspect the adapter weep hole for a fluid leak and for traces of dye within the oil using the J-28428-E  High Intensity Black Light Kit.
5. If fluorescent dye is present within the fluid leak, replace the transmission rear output shaft seal.
6. If fluorescent dye is not present within the fluid leak, replace the transfer case input shaft oil seal. Refer to Input Shaft Seal Replacement 

1. Inspect for a restricted vent hose assembly. Repair as required.
2. Inspect for a leaking wet cavity adapter gasket, adapter damage, or porosity. Replace the adapter or gasket as required. Refer to Transfer Case Adapter Replacement .

1. Inspect the transfer case for an overfill condition. Refer to Transfer Case Fluid Replacement .
   NOTE:

   If a transfer case overfill condition is present in a wet cavity adapter application, the source of the leak may be a faulty transfer case input shaft oil seal. Refer to the transfer case overfill condition diagnosis information within this table.

2. Inspect for a loose, disconnected, restricted, or damaged vent hose assembly.
3. Replace components as required.

1. Inspect for the correct amount and type of sealer on the plugs. Refer to Adhesives, Fluids, Lubricants, and Sealers .
2. Install the correct sealer onto the threads of the plugs and tighten to the correct torque value. Refer to Transfer Case Fluid Replacement .

1. Remove the VSS. Refer to Vehicle Speed Sensor Replacement .
2. Inspect the VSS for the following conditions:
   • Cross threaded
   • Cut or damaged VSS O-ring seal
   • VSS over tightened causing deformation of the sensor
3. Replace the VSS O-ring seal or sensor AS REQUIRED.

1. Inspect for a leaking cup plug in the rear of the propeller shaft slip yoke
2. Replace the yoke assembly as required.

1. Inspect for a restricted vent hose assembly. Repair as required.
2. Inspect for a transfer case for an overfill condition.
   NOTE:

   If a transfer case overfill condition is present in a wet cavity adapter application, the source of the leak may be a faulty transfer case input shaft oil seal. Refer to the transfer case overfill condition diagnosis information within this table.

3. Inspect for a leaking rear output shaft oil seal. Refer to Rear Output Shaft Seal Replacement .
4. Inspect the propeller shaft slip yoke sealing surface for excessive wear, rust, or other damage. Minor abrasions may be repaired using very fine emery cloth sandpaper. Refer to Symptoms - Propeller Shaft .
5. Inspect the rear output shaft bushing for excessive wear. Refer to Transfer Case Rear Extension Bushing Replacement .
6. Replace components as required.

1. Inspect for a restricted vent hose assembly. Repair as required.
2. Inspect for a transfer case for an overfill condition.
   NOTE:

   If a transfer case overfill condition is present in a wet cavity adapter application, the source of the leak may be a faulty transfer case input shaft oil seal. Refer to the appropriate transfer case overfill condition diagnosis information within this table.

3. Inspect for a leaking front output shaft oil seal. Refer to Front Output Shaft Seal Replacement .
4. Replace components as required.

1. Inspect the sensor for porosity or a cut or damaged O-ring seal.
2. Replace components as required.

1. Inspect for a leaking two/four wheel drive actuator motor seal leak.
2. Replace the motor and seal assembly as required.

1. Inspect for a cracked case half or case porosity.
2. Add J-28431-6  Fluorescent Dye to the transfer case.
3. Operate the vehicle.
4. Inspect the transfer case fluid leak for presence of dye within the oil using J-28428-E  High Intensity Black Light Kit. Refer to Transfer Case Disassemble , and Transfer Case Assemble .