Differential Fluid Change - Front

This procedure drains and replaces the front differential fluid on a 2007 Ram 3500 with 5.9L Cummins diesel and 4WD, ensuring proper lubrication of the front axle components.

Warnings

Tools required

Parts

• Front differential drain plug gasket × 1 — Use OEM specification or copper crush washer
• Front differential fill plug gasket × 1 — Use OEM specification or copper crush washer

Fluids

• 75W-90 synthetic gear oil — 3.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Place wheel chocks behind rear wheels
3. If vehicle was recently driven, allow differential to cool for at least 30 minutes
4. Raise front of vehicle using jack and secure with jack stands rated for vehicle weight
5. Ensure adequate clearance to work underneath front axle
6. Locate front differential housing - it is centered between the front wheels
7. Identify drain plug on bottom of differential cover and fill plug on side or rear of housing

Procedure

1. 1

   Clean drain and fill plug areas
   Use wire brush to clean around the drain plug on the bottom of the differential housing and the fill plug on the side/rear of the housing. Remove dirt and debris to prevent contamination when plugs are removed.
2. 2

   Break loose fill plug first
   Using a 3/8 inch ratchet or appropriate socket, break loose the fill plug before removing the drain plug. This ensures you can refill the differential after draining. If the fill plug is seized or damaged, stop and address this issue before draining fluid. Turn counterclockwise to loosen but do not fully remove yet.
3. 3

   Position drain pan and remove drain plug
   Position drain pan directly beneath the differential drain plug. Using appropriate socket, remove the drain plug completely by turning counterclockwise. Allow fluid to drain completely. Inspect drain plug for metal shavings or debris on magnetic surface, which is normal but excessive amounts may indicate wear.
4. 4

   Complete fluid drainage
   Allow differential to drain until fluid flow stops completely, typically 5-10 minutes. While draining, inspect the old fluid condition - it should be dark but not black, and should not smell burnt or contain excessive metal particles.
5. 5

   Inspect and clean drain plug
   Clean the drain plug threads and magnetic tip thoroughly with shop rags. Remove all metal particles and old gasket material from both the plug and the differential housing drain hole surface. Inspect threads for damage.
6. 6

   Install new drain plug gasket
   Place new drain plug gasket onto the drain plug. If using a copper crush washer, ensure it seats properly in the plug recess. Do not reuse the old gasket.
7. 7

   Reinstall drain plug
   Thread drain plug into differential housing by hand first to ensure proper threading. Once hand-tight, use torque wrench to tighten to manufacturer specification. Do not overtighten as this can strip threads or crush gasket excessively. If no torque specification is available, tighten to approximately 40 ft-lbs per Mopar spec for the AAM 9.25 plugs.
8. 8

   Remove fill plug completely
   Remove the fill plug completely from the differential housing. Clean the plug threads and housing threads with a shop rag. Remove old gasket material from fill hole surface.
9. 9

   Fill differential with new fluid
   Using a fluid transfer pump or funnel with extension hose, add 75W-90 synthetic gear oil meeting Chrysler MS-8985 (GL-5) through the fill hole. Fill until fluid begins to seep out of the fill hole opening. The AAM 9.25 front differential requires approximately 3.4 quarts. Add fluid slowly to allow air to escape and prevent overflow.
10. 10

    Verify fluid level
    Fluid level is correct when it reaches the bottom of the fill plug hole and begins to trickle out. Allow a few moments for fluid to settle and level out inside the housing. Add more fluid if necessary until it maintains at the fill hole level.
11. 11

    Install fill plug with new gasket
    Install new fill plug gasket on fill plug. Thread fill plug into housing by hand, then tighten with torque wrench to manufacturer specification. If no specification available, tighten firmly but do not exceed 35 ft-lbs. Wipe away any excess fluid.
12. 12

    Clean up and inspect for leaks
    Wipe down differential housing exterior to remove any spilled fluid. Inspect both drain and fill plugs for signs of leakage. If leaks are present, verify proper torque and gasket installation.

Reassembly

1. Lower vehicle from jack stands carefully
2. Remove wheel chocks
3. Dispose of used differential fluid at appropriate recycling facility - do not pour down drains or on ground

Verification

• Start engine and allow to idle briefly, then shut off
• Check underneath vehicle for any fluid leaks at drain and fill plugs
• Test drive vehicle briefly and make several turns in both directions to circulate fluid through front axle
• After test drive, recheck for leaks with vehicle on level ground
• Monitor differential for leaks over the next few days of driving
• Mark service records with date and mileage for future maintenance tracking

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