Replace the rear differential pinion seal on a 2014 Ram 2500 4WD with 6.7L Cummins to eliminate fluid leaks from the pinion shaft area.

Warnings

Tools required

Parts

• Rear differential pinion seal × 1 — Use OEM specification
• Pinion nut (crush sleeve design) × 1 — Use OEM - may be reusable if not crush sleeve type
• Differential fluid additive (if limited slip) × 1 — Mopar limited slip additive if equipped

Fluids

• Mopar 75W-140 Synthetic Gear Lubricant — 2 qt

Preparation

1. Park vehicle on level surface and set parking brake
2. Chock front wheels securely
3. Raise rear of vehicle and support on jack stands at frame rails
4. Remove rear wheels to improve access and reduce weight on suspension
5. Allow differential to cool if recently driven

Procedure

1. 1

   Mark driveshaft and drain differential
   Use paint marker to mark the relationship between rear driveshaft and pinion flange for reinstallation in same position. Place drain pan under differential. Remove differential cover bolts and carefully pry cover off. Allow gear oil to drain completely. Inspect drained fluid for metal particles indicating internal wear.
2. 2

   Remove rear driveshaft
   Support driveshaft with one hand. Remove the four U-joint strap bolts at the rear axle pinion flange. Carefully lower driveshaft and slide rearward to separate from pinion flange. Secure driveshaft out of work area or remove completely. Do not allow U-joints to bind at extreme angles.
   ⚠Driveshaft weighs approximately 20-30 lbs. Support it to prevent falling or damaging U-joints.
   Torque spec

   Driveshaft U-Joint Straps20 Nm (15 lb-ft)
3. 3

   Mark pinion position and measure bearing preload
   Use paint marker to mark pinion shaft position relative to flange and mark flange position relative to housing. If available, use inch-pound torque wrench to measure pinion rotating torque (should be 15-35 inch-pounds with new bearings). Record this value and count of exposed pinion threads. This provides baseline for reassembly bearing preload.
4. 4

   Remove pinion flange nut
   Use pinion flange holding tool or large pipe wrench to prevent flange rotation. Using large pinion nut socket, count and record the number of turns required to remove the pinion nut. This count will help approximate reinstallation torque. Remove pinion nut completely and set aside (replacement may be required if crush sleeve design).
   ⚠Pinion nut is under high torque (typically 200-400 lb-ft). Ensure holding tool is secure before attempting removal.
5. 5

   Remove pinion flange
   With nut removed, pinion flange should slide off pinion shaft. If tight, use flange puller or gently tap with soft mallet while pulling outward. Do NOT allow pinion shaft to push inward into housing as this will disturb bearing preload and shim pack. Set flange aside and inspect splines for wear or damage.
   ⚠️Do not drive or hammer directly on pinion shaft. This can damage bearings or move the carrier assembly, requiring complete differential rebuild.
6. 6

   Remove old pinion seal
   Using seal puller or small pry bar, carefully remove old pinion seal from housing bore. Work around circumference evenly to prevent cocking the seal. Once removed, thoroughly clean seal bore with brake cleaner and inspect for scoring, burrs, or damage. Clean pinion shaft surface where seal contacts and inspect for grooves or roughness that may have caused leak.
7. 7

   Install new pinion seal
   Lightly coat outer edge of new seal with gear oil and inner lip with fresh gear oil. Position seal squarely in bore with spring side facing inward toward differential. Using appropriately sized seal driver or large socket, carefully drive seal into bore until flush with housing. Tap evenly around circumference to ensure seal seats properly without cocking.
   ⚠Do not damage seal lip during installation. Ensure seal is driven straight and seats completely flush with housing.
8. 8

   Reinstall pinion flange
   Inspect pinion flange seal surface for grooves or wear. Light polishing with fine emery cloth is acceptable if needed. Lightly coat pinion splines with gear oil. Align flange with marks made during disassembly and slide onto pinion shaft. Ensure flange is fully seated against pinion shoulder.
9. 9

   Install and torque pinion nut to set bearing preload
   Thread pinion nut onto shaft (use new nut if crush sleeve equipped). Using holding tool to prevent flange rotation, tighten pinion nut in stages. Initially torque to approximately the turn count recorded during removal. Check rotating torque with inch-pound wrque wrench - should be 15-35 inch-pounds for used bearings. If too loose, continue tightening in small increments (1/4 turn) and recheck. Final nut torque typically 250-450 lb-ft. Do not back off nut to reduce preload - if overtightened, assembly must be disassembled and crush sleeve replaced.
   ⚠️Setting pinion bearing preload is critical. Too loose causes noise and wear; too tight causes bearing failure. If unfamiliar with this procedure, consult factory service manual or seek experienced assistance.
   ⚠Never loosen pinion nut to achieve proper preload. Nut must only be tightened. Backing off destroys crush sleeve setting.
10. 10

    Reinstall driveshaft
    Align marks made during disassembly and position driveshaft U-joint onto pinion flange. Install U-joint strap bolts and torque evenly in cross pattern to specification. Ensure U-joint caps are properly seated in flange yoke.
    Torque spec

    Driveshaft U-Joint Straps20 Nm (15 lb-ft)
11. 11

    Reinstall differential cover and refill
    Clean cover and housing mating surfaces thoroughly. Apply new gasket or RTV silicone as specified (Ram typically uses RTV). Install cover and torque bolts in crisscross pattern to specification. Fill differential through fill plug hole with Mopar 75W-140 synthetic gear lubricant until fluid reaches bottom of fill hole (approximately 2 quarts). Add limited slip additive if equipped with limited slip differential. Install fill plug.
    ℹ️If limited slip differential is equipped, add 4 oz of Mopar limited slip additive to prevent chatter.
    Torque spec

    Differential Cover Bolts35 Nm (26 lb-ft)
12. 12

    Reinstall wheels and lower vehicle
    Install rear wheels and torque lug nuts in star pattern to specification. Lower vehicle from jack stands. Perform final lug nut torque check with vehicle on ground.
    Torque spec

    Wheel Lug Nuts140 Nm (103 lb-ft)

Reassembly

1. Ensure all fasteners are torqued to specification
2. Verify no gear oil leaks from pinion seal or differential cover
3. Check that driveshaft is properly aligned and U-joint straps are secure

Verification

• Start vehicle and verify no unusual noises from differential
• Test drive vehicle at various speeds (15-45 mph) and listen for howling, whining, or grinding from rear axle
• After test drive, recheck pinion area and differential cover for leaks
• Recheck differential fluid level after 50-100 miles of driving
• Monitor for leaks over next several days - pinion seal should remain completely dry

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