GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Place a drain pan under the transaxle bottom pan in order to catch fluid.
  3. Loosen the bottom pan bolts and drain any fluid in the pan.

  4. Object Number: 97463  Size: SH

    Important: Removing the bottom pan on the HYDRA-MATIC 4T80-E will only partially drain the transaxle fluid. The remaining fluid is held in the side cover and in the torque converter.

    Removing the drain plug in the case after the bottom pan removal will drain the fluid from the side cover. It is not necessary to drain the torque converter during most service procedures.

  5. Remove the bottom pan bolts.
  6. Remove the bottom pan.
  7. Remove the gasket.

  8. Object Number: 97465  Size: SH
  9. Remove the left and/or right scavenger screens.
  10. Remove the seals. Use a small screwdriver to pry the seals from the case. Do not score or damage the case.
  11. Inspect the bottom pan and the transaxle case for dents or nicks in the sealing surface. Replace them if they are damaged.
  12. Inspect the bolts for damaged threads. Replace the bolts if they are damaged.
  13. Clean and dry the bottom pan and the case sealing surfaces.
  14. The bottom pan and the case sealing surfaces must be clean and dry for proper sealing.

  15. Clean and dry the bolts and the tapped holes in the case.
  16. The bolts and the tapped holes in the case must be clean and dry in order to maintain the proper bolt torque.

Installation Procedure

  1. Install the new left and right scavenger screens.
  2. Install the new left and right scavenger seals.
  3. Remove any residual transmission fluid from the following components:
  4. • The case
    • Wipe any residual fluid from the outside of the case.
    • The bottom pan
    • The screws
    • Use a rubber tipped hose in order to dry the screws, if necessary. All of the screws must be completely free of transmission fluid upon reinstallation.

    Important: The bottom pan gasket is not reusable. Replace it with a new part after removing the bottom pan for any service.


    Object Number: 97463  Size: SH
  5. Install the bottom pan with the new gasket.
  6. Install the bolts. Tighten the bolts finger tight, and then to specification in proper sequence.
  7. Tighten

        • INITIAL: 3 N·m (27 lb in)
        • INTERMEDIATE: 6 N·m (53 lb in)
        • FINAL: 12 N·m (106 lb in)
  8. Lower the vehicle.
  9. Add DEXTRON®-III transmission fluid as required.
  10. If a complete fluid change is necessary, reset the transaxle oil life indicator. Refer to Electronic Component Description