This procedure drains and refills the automatic transmission fluid on a 2021-2024 Ford F-150 with 3.5L EcoBoost engine, ensuring proper fluid level and transmission longevity.

Warnings

Tools required

Parts

• Transmission drain plug crush washer × 1 — Use OEM specification
• Transmission pan gasket (if reusable gasket is damaged) × 1 — Use OEM specification

Fluids

• Motorcraft MERCON LV ATF — 6 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Place wheel chocks behind rear wheels
3. Allow engine and transmission to cool to ambient temperature (at least 2 hours after operation)
4. Raise front of vehicle using jack and support securely on jack stands rated for vehicle weight
5. Verify vehicle is stable and level before working underneath
6. Locate transmission drain plug on bottom of transmission pan (passenger side of pan)
7. Position drain pan underneath transmission drain plug area

Procedure

1. 1

   Drain transmission fluid
   Using 13mm socket, slowly loosen the transmission drain plug. Allow fluid to drain completely into drain pan. This will take 10-15 minutes for complete drainage. Remove and inspect drain plug and crush washer for damage.
2. 2

   Install drain plug with new washer
   Replace the drain plug crush washer with a new one. Thread drain plug in by hand to ensure proper alignment, then tighten to specification using torque wrench.
   Torque spec

   Drain Plug39 Nm (29 lb-ft)
3. 3

   Inspect transmission pan and gasket
   While underneath vehicle, visually inspect transmission pan for damage, dents, or leaks. Check condition of reusable pan gasket. If gasket shows any tears, compression damage, or hardening, replacement is required. Clean any debris from pan surface.
4. 4

   Lower vehicle
   Carefully lower vehicle from jack stands back to ground level. Ensure vehicle is stable and on level ground for accurate fluid filling.
5. 5

   Locate transmission fill plug
   Open hood and locate transmission fluid fill plug on top of transmission bell housing, driver side. This is a yellow or orange plastic plug labeled 'TRANSMISSION FLUID'. Remove fill plug by turning counterclockwise.
6. 6

   Refill transmission with new fluid
   Using transmission fluid pump or funnel with long neck, add 5.5 quarts of Motorcraft MERCON LV ATF through fill hole. Pour slowly to avoid overflow. After initial fill, wait 2-3 minutes for fluid to settle.
7. 7

   Start engine and check fluid level
   Start engine and allow to idle in Park. With engine running and transmission in Park, check fluid level at fill hole. Fluid should be visible at bottom of fill hole threads but not overflowing. Add additional fluid in 0.25 quart increments if needed, allowing time to settle between additions.
   ⚠Keep hands and tools clear of moving engine components while engine is running.
8. 8

   Cycle transmission through gears
   With engine at idle and foot firmly on brake, shift transmission through all gear positions (P-R-N-D and manual modes if equipped), pausing 3-5 seconds in each position. Return to Park. This circulates new fluid throughout transmission.
9. 9

   Perform final fluid level check
   With engine still running at idle in Park on level ground, recheck fluid level at fill hole. Transmission fluid temperature should be between 80-120°F for accurate level check. Add small amounts of fluid if needed until fluid just reaches bottom of fill hole threads without overflowing.
10. 10

    Install fill plug
    Once proper fluid level is achieved, install fill plug by hand then tighten to specification. Wipe any spilled fluid from transmission housing.
    Torque spec

    Fill Plug39 Nm (29 lb-ft)

Reassembly

1. Ensure fill plug is tightened to proper torque specification
2. Clean any spilled transmission fluid from engine bay and undercarriage
3. Verify drain plug is secure and no leaks are present underneath vehicle
4. Remove drain pan and dispose of used transmission fluid according to local regulations

Verification

• Start engine and allow to reach normal operating temperature while monitoring for leaks at drain plug
• Check transmission operation by test driving vehicle through all gears, verifying smooth shifts with no slipping or harsh engagement
• Recheck fluid level after test drive with engine at operating temperature (150-170°F) in Park on level ground
• Inspect underneath vehicle one final time for any signs of fluid leakage at drain plug
• Reset transmission fluid life monitor if equipped using scan tool or following owner's manual procedure

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