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 Equivalent regional tools: Special Tools Fluorescent Dye Method 1. Add GE-28431-6 Fluorescent Oil 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.
	Transfer case adapter leak	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. 1. Inspect for a restricted vent hose assembly. Repair as required. 2. Add GE-28431-6 Fluorescent Oil Dye to the transmission to determine the source of the leak. 3. Operate the vehicle

	Cause	Correction
		4. Inspect the adapter weep hole for a fluid leak and for traces of dye within the oil using the GE-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. Input Shaft Seal Replacement
	Vent hose leak	1. Inspect the transfer case for an overfill condition. Transfer Case Fluid Replacement 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. Adhesives, Fluids, Lubricants, and Sealers 2. Install the correct sealer onto the threads of the plugs and tighten to the correct torque value. Transfer Case Fluid Replacement
	Rear output shaft bearing snap ring access hole plugs leak	Replace the access hole plugs 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. 3. Inspect for a leaking rear output shaft oil seal. 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. Symptoms - Propeller Shaft 5. 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.

Cause	Correction
	3. Inspect for a leaking front output shaft oil seal. Transfer Case Disassemble and Transfer Case Assemble. 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. Transfer Case Disassemble and Transfer Case Assemble
Case leak	1. Inspect for a cracked case half or case porosity. 2. Add GE-28431-6 Fluorescent Oil Dye to the transfer case. 3. Operate the vehicle 4. Inspect the transfer case fluid leak for presence of dye within the oil using the GE-28428-E High Intensity Black Light Kit. Transfer Case Disassemble and Transfer Case Assemble