Fluid Leak Detection

The following procedure is for detecting transmission fluid leaks from the area between the transmission and the Power Transfer Unit (PTU). When transmission fluid is leaking form the weep hole in the area of the PTU, the seals around the differential output shaft and the differential side gear is most likely faulty. The large seals around the differential output shaft and side gear is serviceable without removing the transmission. The following procedure is recommended to determine which seal is leaking.

1. Raise and support the vehicle. Refer to HOISTING, STANDARD PROCEDURE .
2. Remove the Power Transfer Unit (PTU) from the vehicle. Refer to REMOVAL .
3. Disconnect the transmission vent tube from the adaptor nipple.
4. Adapt a compressed shop air coupling and a length neoprene hose onto the vent nipple.
5. Attach a 48 kPa (7 psi) regulated shop air source to the air coupling on the vent nipple.
6. Apply a soapy solution to the seals inside and around the differential output shaft.
7. Observe over several minutes to see if air bubbles form in the leak area.

Test Results 

• If bubbles are emanating from the inner differential side gear seal, remove the adapter sleeve and replace the inner seal.
• If bubbles are emanating from the outer output shaft seal, remove the adapter sleeve replace the seal.
• If bubbles are emanating from the transmission housing casting, replace the porous component.