Possible Points of Fluid Leaks
WARNING: This page is about a different car, the 2023 GMC Sierra 3500 HD and 2023 GMC Sierra 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Transmission Oil Pan
- Incorrectly tightened oil pan bolts
- Improperly installed or damaged oil pan gasket
- Damaged oil pan or mounting face
- Incorrect oil pan gasket
Case Leak
- Damaged manual shaft seal
- Loose or damaged oil cooler connector fittings
- Worn or damaged propeller shaft oil seal
- Loose line pressure pipe plug
- Porous casting warped torque converter housing
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
- Worn or damaged stator shaft support seal
Leak at the Vent Pipe
- Overfilled system
- Water or coolant in the fluid; The fluid will appear milky
- Transmission case porous
- Incorrect fluid level indicator
- Plugged vent
- Drain-back holes plugged
Leak between Automatic Transmission Case and Transfer Case
- Worn or damaged automatic transmission case extension seal
- Worn or damaged transfer case input seal
- Damage to the transfer case mating surface
- Damage to automatic transmission case mating surface
NOTE:
Area between the automatic transmission and the transfer case is a wet cavity.