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Transfer Case Leak Diagnosis

WARNING: This page is about a different variant/trim than selected.
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.
Transfer case overfill condition (wet cavity applications)
NOTE:
  • Wet cavity adapter applications include transmission RPOs M99/M30/M70.
  • Dry cavity adapter applications include transmission RPOs MYC/MYD.
  • If a transfer case overfill condition is present in a wet cavity adapter application, and the fluid level within the transmission is low, the source of the leak may be a faulty transfer case input shaft oil seal.
  1. Inspect for a transfer case for an overfill condition
    1. Add j-28431-6  Fluorescent Dyeto 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 .
Transfer case adapter leak - (dry cavity applications)
NOTE:
  • Dry cavity adapter applications (transmission RPOs MYC/MYD) with a leak at the adapter weep hole location may caused by either a leaking transmission rear output shaft oil seal or a leaking transfer case input shaft oil seal. The adapter gasket is not the source of the leak.
  • Wet cavity adapter applications (transmission RPOs M99/M30/M70) with a leak may be caused by a leaking adapter gasket, adapter damage, or porosity.
  1. Inspect for a restricted vent hose assembly. Repair as required.
  2. Add J-28431-6  Fluorescent Dyeto 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 
Transfer case adapter leak and/or adapter gasket leak - (wet cavity applications)
NOTE:
  • Wet cavity adapter applications (transmission RPOs M99/M30/M70) with a leak may be caused by a leaking adapter gasket, adapter damage, or porosity.
  • Dry cavity adapter applications (transmission RPOs MYC/MYD) with a leak at the adapter weep hole location may caused by either a leaking transmission rear output shaft oil seal or a leaking transfer case input shaft oil seal. Neither the adapter or the gasket is the source of the leak.
  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 .
Vent hose leak
  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.
Drain plug or fill plug leak
  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 .
Rear output shaft bearing snap ring access hole plugs leak Replace the access hole plugs AS REQUIRED.
Vehicle speed sensor (VSS) leak
  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.
Propeller shaft slip yoke cup plug leak
  1. Inspect for a leaking cup plug in the rear of the propeller shaft slip yoke
  2. Replace the yoke assembly as required.
Rear output shaft oil seal leak
  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.
Front output shaft oil seal leak
  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.
Actuator shaft position sensor or O-ring seal leak
  1. Inspect the sensor for porosity or a cut or damaged O-ring seal.
  2. Replace components as required.
Two/four wheel drive actuator seal leak
  1. Inspect for a leaking two/four wheel drive actuator motor seal leak.
  2. Replace the motor and seal assembly as required.
Front case half-to-rear case half seam leak Disassemble the transfer case and reseal the case halves. Refer to Transfer Case Disassemble , and Transfer Case Assemble .
Case Leak
  1. Inspect for a cracked case half or case porosity.
  2. Add J-28431-6  Fluorescent Dyeto 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 .
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