Replace the transmission cooler lines that run between the transmission and the radiator-mounted cooler to fix leaks or prevent failure on the 6R80 automatic transmission.

Warnings

Tools required

Parts

• Transmission cooler line set (inlet and outlet) × 1 — Use OEM Ford parts or direct fit replacement
• Transmission cooler line O-rings × 4 — Included with cooler lines or OEM
• Transmission drain plug crush washer × 1 — Use OEM specification

Fluids

• Motorcraft MERCON LV ATF — 4 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow transmission to cool completely if recently driven
3. Raise and safely support the front of the vehicle on jack stands
4. Place drain pan under transmission to catch fluid
5. Remove the engine belly pan or skid plate if equipped

Procedure

1. 1

   Drain transmission fluid
   Locate the transmission drain plug on the bottom of the transmission pan. Remove the drain plug and allow fluid to drain completely into the drain pan. Once drained, reinstall the drain plug with a new crush washer.
   Torque spec

   Transmission Drain Plug30 Nm (22 lb-ft)
2. 2

   Access radiator cooler line connections
   From the top of the engine bay, locate the transmission cooler lines where they connect to the radiator on the driver's side. Clean the area around the connections to prevent contamination. Note the routing of the lines for reinstallation.
3. 3

   Disconnect cooler lines at radiator
   Using the appropriate line disconnect tool or flare nut wrench, carefully disconnect both cooler lines from the radiator. Be prepared for residual fluid to drain. If the fittings are severely corroded, apply penetrating oil and allow to soak. In extreme corrosion cases, the line may need to be cut near the fitting.
   ⚠Do not use standard wrenches on the fittings as this will round off the soft aluminum. Use flare nut wrenches or proper quick-disconnect tools.
4. 4

   Trace and support cooler lines
   Follow the cooler lines from the radiator down to the transmission, noting all mounting clips and brackets. The lines run along the driver's side of the vehicle. Remove any clips or fasteners securing the lines to the frame or body.
5. 5

   Disconnect lines at transmission
   From underneath the vehicle, locate where the cooler lines connect to the transmission case on the driver's side. Clean the connection area thoroughly. Use the appropriate quick-disconnect tool to release the lines from the transmission fittings. Pull the lines straight out to avoid damaging the O-rings in the transmission case.
6. 6

   Remove old cooler lines
   Carefully maneuver the old cooler lines out from their routing path. Note the exact routing, especially where they pass near hot exhaust components or moving drivetrain parts. Take photos if necessary for reference during installation.
7. 7

   Inspect transmission and radiator fittings
   Inspect the transmission case fittings and radiator fittings for damage, cracks, or excessive corrosion. Clean the transmission fittings with a lint-free cloth. If the radiator fittings are damaged, radiator service or replacement will be required.
8. 8

   Prepare new cooler lines
   Unpack the new cooler lines and verify correct fitment. Install new O-rings on the transmission end fittings if not pre-installed. Lightly lubricate the O-rings with clean MERCON LV ATF. Ensure the lines are clean and free of debris internally.
9. 9

   Route new cooler lines
   Route the new cooler lines following the exact path of the original lines. Ensure they do not contact exhaust components, moving parts, or sharp edges. Maintain proper clearance from the frame and other components. Secure with original mounting clips and brackets.
10. 10

    Connect lines to transmission
    Push each cooler line firmly into the transmission case fitting until you hear or feel a positive click. Verify the connection by pulling back on the line to ensure it is locked in place. The line should not pull free with moderate force.
11. 11

    Connect lines to radiator
    Install new O-rings on the radiator fittings if required by the line design. Connect each line to the radiator using the appropriate fittings. If threaded fittings are used, tighten carefully by hand first, then snug with a flare nut wrench. Do not overtighten aluminum fittings.
12. 12

    Refill transmission fluid
    With the vehicle still raised, locate the transmission fill plug on the side of the transmission case. Remove the fill plug and add MERCON LV ATF through the fill hole using a fluid pump until fluid begins to drip from the fill hole. Reinstall the fill plug.
13. 13

    Check fluid level and test
    Lower the vehicle. Start the engine and allow it to reach operating temperature. Shift through all gear ranges, pausing in each position. With the engine running and transmission in Park on level ground, recheck the fluid level per the dipstick or fill plug method. Add fluid as needed to bring to proper level.

Reassembly

1. Reinstall the engine belly pan or skid plate if removed
2. Verify all mounting clips and brackets are secured
3. Double-check all connections for proper seating and engagement

Verification

• With engine at operating temperature, inspect all connection points for leaks while transmission is in Park
• Test drive the vehicle through all gear ranges and recheck for leaks at radiator and transmission connections
• After test drive, recheck transmission fluid level with engine running and adjust as necessary
• Inspect the ground under the vehicle after overnight parking for any signs of ATF leakage

More procedures for this vehicle