GM Service Manual Online
For 1990-2009 cars only

Oil Out the Vent or Foaming

Checks

Cause

Oil Level

Overfilled transmission

Foaming Transmission Oil

    • Contaminated with antifreeze
    • Engine overheating
    • Lube pipes leaking

Foaming Oil Filter or Seal

    • Damaged seal assembly
    • Cracked or damaged filter assembly

Thermo Element in the Case

    • Does not close when hot
    • Not insulated correctly
    • Incorrect pin heights

Upper Channel Plate Gasket

Damaged or incorrectly installed gasket

Drive Sprocket Support

Plugged drain back holes