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Power Transfer Unit Case Leak Diagnosis

Cause Correction
DEFINITION: A visible indication of an external fluid leak from the power transfer unit.
Review the Symptoms - Power Transfer Unit Case , and Power Transfer Unit Case Description and Operation  and perform the necessary inspections. See below for suggested diagnostic method(s).

Special Tools

  • GE-28431-6  Fluorescent Oil Dye
  • GE-28428-E  High Intensity Black Light Kit
For equivalent regional tools, refer to Special Tools .

Fluorescent Dye Method

  1. Add GE-28431-6  Fluorescent dye to the transmission or power transfer unit 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.
    3. 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.
Drain plug or fill plug leak
  1. Inspect for dirty, worn, scored sealing surfaces, or missing drain and/or fill plug sealing washers.
  2. Replace as required.
Restricted or damaged ventilation hose assembly Replace the ventilation hose assembly, as required.
Leaking at the power transfer unit left side weep hole
  1. Operate the vehicle.
  2. Inspect for an oil leak at the weep hole location. Refer to Power Transfer Unit Case Description and Operation  for the weep hole location.
NOTE:

An oil leak at the power transfer unit weep hole location is caused by the power transfer unit input shaft oil seal-front.

Replace input shaft oil seal - front.
Leaking at the power transfer unit right side weep hole
A transmission or gear oil leak at the power transfer unit right side weep hole is caused by the input shaft seal located in the extension housing.		 Replace the input shaft seal-rear.
Leaking ATF at the right side axle shaft-to-intermediate shaft bearing location. Replace the intermediate drive shaft seal located in the output end of the extension housing.
Leaking at rear output shaft area
A leak at rear output shaft area is caused by either the rear output shaft seal or the rear output shaft housing O-ring seal.		 Inspect and replace the rear output shaft seal as required.
The O-ring is not serviceable on AAM power transfer unit.
Leaking at transaxle assembly-to-transfer case interface
A transmission oil leak at the transmission-to-power transfer unit interface may be caused by the transmission-to-power transfer unit O-ring seal or face seal.
  1. Identify the type of oil leak.
  2. Replace components as required.
    NOTE:

    If the leak is transmission or O-ring or face seal related, do not replace the power transfer unit input shaft seals.
Case half leak at the idler gear shaft tube location Disassemble and replace the idler gear shaft tube O-ring seals as required.
Case half seam leak AAM Disassemble and replace the power transfer unit-to-rear extension housing O-ring seal.
Leaking through case
  • Inspect for a cracked case.
  • Inspect for case porosity.
Replace the components as required.
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