Fluid Filter - A/T: Service and Repair

REMOVAL PROCEDURE
The HYDRA-MATIC 4T80-80 transmission has a filter under the side cover that requires service only during transmission overhaul. Scavenging screens are beneath the bottom pan, which you must replace when you change the transmission fluid.

1. Raise the vehicle and support.
2. Place a drain pan under the transmission bottom pan in order to catch the fluid.

Important: Removing the bottom pan on the HYDRA-MATIC 4T80-E only partially drains the transmission fluid. The remaining fluid is held in the in the side cover and the torque converter. Removing the drain plug in the case after removal of the bottom pan will drain fluid from the side cover. You do not need to drain the torque converter during most service procedures.

3. Loosen the bottom pan bolts. Drain any fluid in the pan.
4. Remove the drain plug in the transmission case.
5. Remove the bottom pan, the transmission case bolts, and the seal.
6. Remove the left and the right scavenger screens.
7. Inspect the following parts for the conditions cited:
- The scavenger screen lip seals in the transmission case for nicks or cuts. If damaged, replace.
- The bottom pan and the transmission case for dents or nicks in the sealing surfaces. If damaged, replace.
- The bolts for damaged threads. If damaged, replace. For proper seating, the bottom pan and the case sealing surfaces must be clean and dry. In order to maintain proper bolt torque, the bolts and the tapped holes in the case must be clean and dry.

Important: The bottom pan seal is NOT reusable. Replace the pan seal with a new part after removing the pan for any service.

INSTALLATION PROCEDURE
1. Install the drain plug in the transmission case.
2. Install new left and right scavenger screens.
3. Install the bottom pan and a new seal. Finger tighten the bolts.





4. Tighten each of the 16 bolts 3 times in the sequence shown.

NOTICE: Always use the correct fastener in the correct location. When you replace a fastener, use ONLY the exact part number for that application. The manufacturer will call out those fasteners that require a replacement after removal. The manufacturer will also call out the fasteners that require thread lockers or thread sealant. UNLESS OTHERWISE SPECIFIED, do not use supplemental coatings (paints, greases, or other corrosion inhibitors) on threaded fasteners or fastener joint interfaces. Generally, such coatings adversely affect the fastener tightening sequence and specifications. Following these instructions can help you avoid damage to parts and systems.

- Tighten:
^ 1st Time: Tighten the pan bolts to 3 Nm (27 inch lbs.).
^ 2nd Time: Tighten the pan bolts to 6 Nm (53 inch lbs.).
^ 3rd Time: Tighten the pan bolts to 12 Nm (106 inch lbs.).
5. Lower the vehicle.
6. Add DEXRON-III transmission fluid as required. Refer to FLUID LEVEL INSPECTION AND TO FLUID CAPACITY.
7. Reset the transmission adapts. Refer to ELECTRONIC COMPONENT DESCRIPTION.
8. Reset the transmission oil life indicator. Refer to ELECTRONIC COMPONENT DESCRIPTION.