Differential Cover Gasket

This procedure covers the replacement of the differential cover gasket on a 2007-2013 Mercedes-Benz S65 AMG, including draining and refilling the differential with the proper fluid.

Warnings

Tools required

Parts

• Differential cover gasket × 1 — Use OEM specification
• Differential drain plug seal/washer (if equipped) × 1 — Use OEM specification

Fluids

• Mercedes-Benz Diff Fluid 75W-85 — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow differential to cool if vehicle was recently driven
3. Raise vehicle on lift or securely support on jack stands at all four corners
4. Remove rear wheels to improve access if needed (optional but recommended)
5. Clean exterior of differential cover and surrounding area to prevent contamination

Procedure

1. 1

   Drain differential fluid
   Position drain pan beneath the differential cover. If equipped with a drain plug, remove it first and allow fluid to drain completely. If no drain plug is present, carefully begin loosening the differential cover bolts starting from the top, leaving 2-3 bolts partially threaded at the top to control fluid release. Gradually loosen lower bolts to allow fluid to drain into pan. Once drained, remove all remaining bolts.
2. 2

   Remove differential cover
   Carefully pry the differential cover away from the housing using a plastic scraper if needed. Be gentle to avoid damaging the sealing surface on the differential housing. Remove the cover completely and set aside. Inspect the interior for metal shavings or debris that may indicate wear issues.
3. 3

   Clean sealing surfaces
   Remove all old gasket material from both the differential housing and the cover using a plastic or brass gasket scraper. Take care not to gouge or scratch the aluminum sealing surfaces. Clean both surfaces thoroughly with brake cleaner and wipe with lint-free rags. Ensure no debris falls into the differential housing.
4. 4

   Inspect differential cover and magnet
   Clean the differential cover thoroughly, including the magnetic drain plug (if equipped). Inspect the cover for cracks or damage. Check the magnet for excessive metal particles - a small amount of fine metallic dust is normal, but large chunks or excessive material may indicate internal wear. Clean the cover interior and magnet completely.
5. 5

   Install new gasket
   Position the new differential cover gasket onto the cover or housing as designed. Some gaskets may have adhesive backing; others may require careful alignment during installation. Ensure the gasket is properly seated and all bolt holes align correctly. Do not use additional sealant unless specified by Mercedes-Benz.
6. 6

   Install differential cover
   Carefully position the differential cover with gasket onto the housing, ensuring proper alignment. Thread all differential cover bolts by hand first to prevent cross-threading. Tighten bolts in a criss-cross pattern, working from the center outward, gradually bringing them to finger-tight before final torquing.
7. 7

   Torque differential cover bolts
   Using a torque wrench, tighten the differential cover bolts to specification in a criss-cross pattern. Make multiple passes, gradually increasing torque to the final specification to ensure even gasket compression and prevent leaks.
   Torque spec

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

   Refill differential with fluid
   Locate the differential fill plug on the side of the housing. Remove the fill plug before beginning to add fluid to ensure it is not seized. Using a fluid transfer pump, add approximately 2 quarts of Mercedes-Benz 75W-85 differential fluid through the fill hole. Fill until fluid begins to seep from the fill hole, indicating proper level. The differential should be filled to the bottom of the fill plug opening when on level ground.
9. 9

   Install fill plug and check for leaks
   Install the differential fill plug with a new seal/washer if applicable and tighten to specification. Wipe the differential cover area clean and inspect for any signs of fluid leakage around the gasket. If leaks are present, verify bolt torque and gasket installation.
10. 10

    Reinstall wheels and lower vehicle
    If wheels were removed, reinstall them and torque lug nuts to specification in a star pattern. Carefully lower the vehicle to the ground. Dispose of used differential fluid properly at a recycling center or auto parts store.
    Torque spec

    Wheel Lug Nuts140 Nm (103 lb-ft)

Reassembly

1. Ensure all fasteners are torqued to specification
2. Double-check that the fill plug is installed and tight
3. Verify differential fluid level is correct with vehicle on level ground

Verification

• Start the engine and verify no leaks around the differential cover
• Test drive the vehicle for 5-10 minutes, then recheck for leaks with vehicle on level ground
• After 50-100 miles of driving, inspect the differential cover area again for any seepage
• Verify proper differential operation with no unusual noises or vibrations

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