This procedure performs a complete transmission fluid flush and filter replacement on the 6R80 automatic transmission, removing old fluid and contaminants to maintain transmission performance and longevity.

Warnings

Tools required

Parts

• Transmission pan gasket × 1 — BC3Z-7A191-A or equivalent
• Transmission fluid filter × 1 — BC3Z-7A098-A or equivalent
• Transmission drain plug crush washer × 1 — Use OEM specification

Fluids

• Motorcraft MERCON LV ATF — 11 qt

Preparation

1. Park vehicle on level surface and apply parking brake firmly
2. Place wheel chocks behind rear wheels
3. Start engine and allow transmission to reach operating temperature (180-200°F), then shut off and allow to cool for 2 hours minimum
4. Raise front of vehicle and support securely on jack stands at frame rails
5. Raise rear of vehicle and support on jack stands to keep transmission level for accurate fill
6. Remove plastic skid plate or underbody panels if equipped to access transmission pan

Procedure

1. 1

   Drain transmission fluid via drain plug
   Locate the drain plug on the bottom of the transmission pan (driver's side). Position drain pan beneath plug. Using appropriate socket, slowly loosen drain plug while maintaining pressure to prevent it from falling. Once loose, remove by hand and allow fluid to drain completely (approximately 5-6 quarts). Inspect drain plug and threads for damage. Remove and discard old crush washer from drain plug.
2. 2

   Remove transmission pan bolts
   Starting from the rear corners and working forward, loosen all transmission pan bolts in a criss-cross pattern. Leave two front bolts partially threaded to support pan weight. Carefully lower rear of pan to drain remaining fluid into drain pan. Once drained, remove final two bolts and lower pan carefully. Inspect pan interior for excessive debris, metal shavings, or clutch material which may indicate internal transmission issues.
3. 3

   Remove old transmission filter
   The transmission filter is secured to the valve body with bolts. Locate and remove the filter mounting bolts using appropriate socket. Carefully lower the filter assembly, noting its orientation. Some residual fluid will drain from the filter cavity. Inspect the filter for excessive debris or metal particles. Remove and discard the old filter seal/O-ring from the valve body.
4. 4

   Clean transmission pan and mating surfaces
   Thoroughly clean the inside of the transmission pan, removing all old gasket material, sludge, and debris. Clean the magnet in the pan and inspect for excessive metal particles. Use plastic scraper to carefully remove all old gasket material from both the pan and transmission case mating surfaces. Do not gouge or scratch the aluminum surfaces. Wipe both surfaces clean with lint-free rags. Ensure no debris or gasket material falls into the transmission case.
5. 5

   Install new transmission filter
   Install new O-ring or seal onto the new filter assembly. Lubricate the seal with clean MERCON LV fluid. Position the new filter into the valve body in the same orientation as the old filter. Install and hand-tighten the filter mounting bolts, then torque to specification in a criss-cross pattern.
   Torque spec

   Sensor Bolts12 Nm (9 lb-ft)
6. 6

   Install new pan gasket and pan
   Position new transmission pan gasket onto the pan. Some gaskets are adhesive-backed and stick to the pan; others may require careful alignment during installation. Lift the pan with gasket into position against the transmission case, ensuring gasket remains properly aligned. Install all pan bolts finger-tight first to ensure proper gasket seating.
7. 7

   Torque transmission pan bolts
   Beginning at the center and working outward in a criss-cross pattern, torque all transmission pan bolts to specification. This ensures even gasket compression and prevents leaks. Make multiple passes, gradually increasing torque to final specification.
   Torque spec

   Pan Bolts19 Nm (14 lb-ft)
8. 8

   Install drain plug with new crush washer
   Install new crush washer onto the drain plug. Thread drain plug into transmission pan by hand to avoid cross-threading. Torque drain plug to specification. Do not overtighten as this may strip the aluminum pan threads.
   Torque spec

   Transmission Drain Plug30 Nm (22 lb-ft)
9. 9

   Fill transmission with new MERCON LV fluid
   Lower vehicle to ground level to ensure accurate fill. Locate the transmission fluid fill plug on the driver's side of the transmission case (accessed from underneath). Remove fill plug. Using fluid pump or funnel with extension tube, add approximately 5.5 quarts of Motorcraft MERCON LV ATF through the fill hole. This replaces fluid lost from pan and filter service. Do not overfill at this stage.
10. 10

    Check fluid level using overflow method
    With vehicle still level on ground, start engine and allow to idle. With parking brake applied and foot on brake pedal, shift transmission through all gear ranges (P-R-N-D-L) pausing 3 seconds in each. Return to Park. With engine still running at idle, remove the overflow plug (separate from fill plug, usually located higher on case). Fluid should drip slowly from overflow hole. If no fluid drips, add fluid through fill hole in 0.5 quart increments until fluid begins to drip from overflow. When fluid drips steadily at idle with transmission at operating temperature (180-200°F), the level is correct.
11. 11

    Install overflow and fill plugs
    With fluid dripping from overflow hole and transmission at operating temperature, install overflow plug and torque to specification. Install fill plug and torque to specification. Shut off engine.
    Torque spec

    Transmission Drain Plug30 Nm (22 lb-ft)
12. 12

    Perform test drive and recheck
    Raise vehicle and inspect transmission pan, drain plug, and overflow plug areas for leaks. Lower vehicle and test drive for 10-15 minutes, allowing transmission to shift through all gears under normal driving conditions. Return to level surface and recheck fluid level using overflow method with transmission at operating temperature. Top off if necessary. Inspect again for leaks.

Reassembly

1. Reinstall any underbody panels or skid plates that were removed for access
2. Verify all drain and fill plugs are properly torqued and not leaking
3. Record mileage and service date for maintenance records

Verification

• With engine running and transmission at operating temperature, verify fluid drips from overflow hole when plug is removed
• Test drive vehicle and verify smooth shifting through all gear ranges with no slipping or harsh engagements
• Verify no fluid leaks from transmission pan, drain plug, overflow plug, or fill plug after test drive
• Check that transmission operates normally in all modes (tow/haul, sport, etc.) if equipped
• Verify proper fluid color (red) with no burning smell indicating successful flush

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