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 Add GE-28431-6 Fluorescent dye to the transmission or power transfer unit to determine the source of the leak. Operate the vehicle. 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. Thoroughly clean the suspected leak area using a rag. 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. Operate the vehicle for 15 - 20 minutes under city driving conditions until normal operating temperatures are reached. Shut OFF the engine. Inspect the suspected leak area. Trace the leak path through the powder in order to find the source of the leak.
Drain plug or fill plug leak Damaged or broken Low torque Missing seal	Inspect for dirty, worn, scored sealing surfaces, or missing drain and/or fill plug sealing washers. Verify torque - Fastener Specifications Replace as required. Follow fluorescent dye method to verify leak if needed.
Restricted or damaged ventilation hose/vent assembly	Replace the ventilation hose/vent assembly, as required.
Leaking at: Transaxle-to-transfer case interface Transaxle-to-adapter plate interface (if equipped by adapter plate) Adapter plate-to-transfer case interface (if equipped by adapter plate) A transmission oil leak at the interface may be caused by the O-ring seal or face seal. NOTE: An ATF leak at the transaxle-to-transfer case interface may be cause by the transfer case adapter seal or a damaged sealing surface. If the leak is transmission or O-ring related, do not replace the transfer case.	Identify the location of leak and type of fluid. Replace the interface seal as required. Transfer case replacement is required only if sealing surface on transfer case is damaged. Adapter plate replacement is required only if sealing surface on adapter plate case is damaged (if equipped by adapter plate).
Leaking at the power transfer unit left side weep hole - main housing NOTE: An automatic transmission fluid (ATF) or transfer case gear oil leak at the weep hole in the housing is caused by the input shaft seal located in the main housing.	Replace components as required. Inspect for an oil leak at the weep hole location. Refer to Power Transfer Unit Case Description and Operation for the weep hole location. Replace input shaft oil seal in main housing. Follow fluorescent dye method to verify leak if needed.
Leaking at the power transfer unit right side weep hole - extension housing NOTE: An automatic transmission fluid (ATF) or transfer case gear oil leak at the weep hole in the housing is caused by the input shaft seal located in the rear extension housing.	Replace components as required. Inspect for an oil leak at the weep hole location. Refer to Power Transfer Unit Case Description and Operation for the weep hole location. Replace the rear input shaft oil seal. Follow fluorescent dye method to verify leak if needed.
Leaking ATF at the intermediate drive shaft seal location in the end of the extension housing.	Inspect and replace the intermediate drive shaft as required. This seal is located in the output end of the extension housing. Inspect the intermediate drive shaft bearing for excessive wear. A worn intermediate drive shaft bearing may cause excessive shaft runout and seal leakage. Replace the intermediate drive shaft bearing as required.
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.
Case half seam leak	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 components/transfer case as required. Ensure this leak is not from the weep hole location.
Leak through the actuator interface to power transfer unit	Inspect and replace the actuator assembly seal as required. Ensure this leak is not from the weep hole location.