GM Service Manual Online
For 1990-2009 cars only

If you traced the leak back to the source, the cause of the leak must be determined for the leak to be correctly repaired. If the sealing flange is bent, you cannot repair the leak by replacing the gasket. The bent flange must also be repaired. Before attempting to repair a leak, certain conditions should be checked and corrected if necessary. The following conditions may cause a leak:

Gasket Leakage

    • The fluid level or the pressure is too high.
    • Plugged vent holes or drain-back holes
    • Incorrectly torqued fasteners, dirty threads, or damaged threads
    • Warped flanges or warped sealing surfaces
    • Scratches, burrs, or other damage to the sealing surfaces
    • A damaged gasket or a worn gasket
    • The component has cracks or is porous.
    • An incorrect sealant was used
    • An incorrect gasket

Seal Leakage

    • The fluid level or the pressure is too high.
    • Plugged vent holes or plugged drain-back holes
    • A damaged seal bore
    • A damaged seal or a worn seal
    • Incorrect installation
    • Cracks in the component
    • Scratched, nicked, or damaged surfaces of the manual output shaft
    • A loose bearing or a worn bearing that causes seal wear

Possible Points of Fluid Leaks

Tools Required

    • J 28428-E High Intensity Black Light
    • J 28431-6 Fluorescent Oil Additive
   • 
Object Number: 218102  Size: SH
  • Bolts that are incorrectly tightened.
  •    • 
  • A gasket that is incorrectly installed or damaged.
  •    • 
  • A damaged fluid pan.
  •    • 
  • An incorrect gasket (1).
  • Vent Leakage

        • Test the fluid level indicator for a high level.
        • Test the fluid color for water or for coolant in fluid. The fluid will appear milky.
        • Test for an incorrect fluid level indicator.
        • Test for a plugged vent or for a restricted vent.
        • Test for plugged drain-back holes or for restricted drain-back holes.
        • Test for a misaligned fluid pump-to-case gasket.
        • Test for porous casting.

    Case Leakage

       • 
    Object Number: 218107  Size: SH
  • Test the filler tube O-ring (3).
  •    • 
  • Test the filler tube bracket.
  •    • 
  • Test the TV cable seal.
  •    • 
  • Test the seal of the Vehicle Speed Sensor (VSS).
  •    • 
  • Test the connector fittings of the fluid cooler.
  •    • 
  • Test the speedometer driven gear seal.
  •    • 
  • Test the fluid seal (2) of the manual shift shaft.
  •    • 
  • Test the intermediate servo cover seal (4).
  •    • 
    Object Number: 218109  Size: SH
  • Test the rear cover gasket (1).
  •    • 
  • Test the transaxle case housing-to-case gasket.
  •    • 
  • Test the drive shaft seals.
  •    • 
  • Test for porous casting.
  • Converter Side Leakage

        • The converter seal is damaged.
           - The seal lip is cut. Test the converter hub for damage.
           - The garter spring is missing from the seal.
        • The converter has a leak in the weld area. Replace the torque converter.
        • The casting of the case or of the pump is porous.