Possible Points of Fluid Leaks

Transmission Oil Pan

• Incorrectly tightened fluid pan bolts
• Improperly installed or damaged fluid pan gasket
• Damaged fluid pan or mounting face
• Incorrect fluid pan gasket

Case Leak

• Fluid Fill Plug
• Extension Housing
• Wiring harness O-ring seal
• Damaged manual shaft seal
• Loose or damaged fluid cooler line seals fittings
• Worn or damaged propeller shaft flange seal
• Loose line pressure test plug
• Porous casting

Leak at the Torque Converter End

• Converter leak in the weld area
• Converter seal lip cut. Check the converter hub for damage
• Converter seal bushing moved forward and damaged
• Converter seal garter spring missing from the seal
• Porous casting of the transmission case or the oil pump

Leak at the Vent

• Overfilled system
• Water or coolant in the fluid. The fluid will appear milky
• Transmission case porous
• Plugged vent
• Drain-back holes plugged
• Mispositioned oil pump to case gasket, if equipped

Fig 1: Identifying Leak Inspection Points

Courtesy of GENERAL MOTORS CORP.