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. 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 transfer case 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	Inspect for dirty, worn, scored sealing surfaces, or missing drain and/or fill plug sealing washers. Replace as required.
Restricted or damaged ventilation hose assembly	Replace the ventilation hose assembly, as required.
Leaking ATF at the transaxle -to-transfer case interface	NOTE: An ATF leak at the transaxle-to-transfer case interface may be caused 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 input shaft bearing retainer front seal. Identify the location of the leak and type of fluid. Replace the transfer case adapter seal as required. Refer to Transfer Case Replacement .
Leaking at the transfer case vent hole - main housing	NOTE: An ATF leak at the transaxle-to-transfer case interface may be caused 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 input shaft bearing retainer front seal. An automatic transmission fluid (ATF) or transfer case gear oil leak at the transfer case vent hole is caused by the transfer case input shaft bearing retainer front seal.Replace components as required.Refer to Transfer Case Description and Operation , and Transfer Case Replacement .
Leaking at the transfer case vent hole - extension housing	NOTE: An automatic transmission fluid (ATF) or transfer case gear oil leak at the extension housing vent hole is caused by the input shaft bearing retainer seal located in the rear extension housing. Replace the transfer case input shaft bearing retainer rear seal.Refer to Transfer Case Description and Operation , and Transfer Case Replacement .
Leaking ATF at the intermediate shaft bearing location	NOTE: The front wheel drive intermediate shaft bearing seal is a dirt and debris seal only and not a fluid retaining seal and is not the source of a fluid leak. Inspect the front wheel drive intermediate shaft (IDS) bearing for excessive wear. A worn IDS shaft bearing may cause excessive shaft runout and seal leakage. Replace the front wheel drive intermediate shaft bearing as required. Replace the front wheel drive intermediate shaft seal and the front wheel drive intermediate shaft housing seal. Refer to Transfer Case Disassembled View , and Transfer Case Description and Operation .
Leaking at rear output shaft area	NOTE: A transfer case gear oil leak at rear output shaft area may be caused by either the rear output shaft seal, the rear output flange with damage to the seal surface, or a leaking rear output shaft housing O-ring seal. Replace the components as required.Refer to Transfer Case Description and Operation .
Case half seam leak AAM	Disassemble and replace the transfer case-to-rear extension housing O-ring seal.
Leaking through the case	Inspect for a cracked case. Inspect for case porosity. Replace the components as required.