This procedure covers replacement of the rear differential cover gasket on a 2015-2020 Ford F-150 with 3.5L EcoBoost engine, including fluid drain, gasket replacement, and refill.

Warnings

Tools required

Parts

• Differential cover gasket × 1 — Use OEM specification or Motorcraft BR3Z-4033-A
• Differential cover bolts (if corroded) × 1 — Use OEM specification

Fluids

• Motorcraft 75W-140 Synthetic Gear Oil — 2.5 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. Place wheel chocks in front of front wheels
3. Raise rear of vehicle using floor jack at rear axle differential pumpkin
4. Support vehicle with jack stands under frame rails
5. Allow differential to cool to ambient temperature if recently driven

Procedure

1. 1

   Position drain pan
   Place drain pan directly beneath the differential cover. The cover holds approximately 2 quarts of gear oil and will drain quickly when removed.
2. 2

   Loosen differential cover bolts
   Using a 10mm socket, loosen all differential cover bolts in a crisscross pattern, but do not remove them completely yet. Loosen the top bolts last to allow the cover to tilt and drain more controllably.
3. 3

   Remove lower bolts and drain fluid
   Remove the lower differential cover bolts first, allowing the cover to tilt downward at the bottom. Gear oil will begin draining. Once flow slows, remove remaining bolts and carefully remove the cover. Allow all fluid to drain completely into the pan.
4. 4

   Clean differential housing mating surface
   Use a plastic gasket scraper to carefully remove all old gasket material from the differential housing mating surface. Do not gouge or scratch the aluminum surface. Wipe clean with brake cleaner and a rag. Ensure no debris falls into the differential.
5. 5

   Clean differential cover
   Remove old gasket material from the differential cover using the plastic scraper. Clean thoroughly with brake cleaner. Inspect for cracks or damage. Inspect the magnetic drain plug (if equipped) and clean off metal shavings, which is normal wear material.
6. 6

   Install new gasket
   Position the new differential cover gasket onto the cover. Some gaskets have adhesive backing; others may require a light coating of RTV on the cover side only. Align all bolt holes carefully.
7. 7

   Install differential cover
   Carefully position the differential cover with new gasket onto the housing. Start all bolts by hand to ensure proper alignment. Do not force bolts if they do not thread easily.
   Torque spec

   Differential Cover Bolts35 Nm (26 lb-ft)
8. 8

   Torque cover bolts
   Torque the differential cover bolts to specification in a crisscross pattern, working from the center outward. Make multiple passes, gradually increasing torque to final specification to ensure even gasket compression.
   Torque spec

   Differential Cover Bolts35 Nm (26 lb-ft)
9. 9

   Refill differential with gear oil
   Locate the differential fill plug on the front of the differential housing (10mm allen head or 10mm hex). Remove the fill plug. Using a fluid pump or funnel with hose, add Motorcraft 75W-140 Synthetic Gear Oil until it begins to drain from the fill hole. Capacity is approximately 2.0-2.5 quarts depending on configuration. Reinstall fill plug when fluid reaches bottom of fill hole.
10. 10

    Clean and lower vehicle
    Wipe any spilled gear oil from the differential housing and surrounding components. Remove jack stands and carefully lower the vehicle to the ground. Remove wheel chocks.

Reassembly

1. Ensure all differential cover bolts are torqued to specification in a crisscross pattern
2. Verify fill plug is securely reinstalled after filling differential
3. Dispose of used gear oil at appropriate recycling facility

Verification

• Start engine and allow to idle briefly, then check underneath for any gear oil leaks around the differential cover
• Drive vehicle 5-10 miles, then recheck for leaks around differential cover and fill plug
• Check gear oil level at fill plug after test drive to ensure proper fill level
• Monitor for any unusual differential noise during test drive

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