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Autopapyrus · Opel Mokka 1.8 A18XER (2014)
https://autopapyrus.com/guides/opel/mokka/rear-axle-differential-rear-drive-unit-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Opel Mokka 1.8 A18XER (2014): Rear Axle Differential (Rear Drive Unit) Replacement

The rear axle differential on the Opel Mokka 4x4 with the 1.8 A18XER engine is a key component of the all-wheel-drive system. It distributes torque to the rear wheels through an electromagnetic coupling. Typical reasons for replacement: oil leaks caused by corrosion of the aluminum housing, humming or grinding noise while driving, coupling lock-up in turns, and an "AWD Service" error message on the instrument cluster.

Difficulty: Hard Time: 2-3 hours Steps: 20 Tools: Lift, or an inspection pit with a jack; transmission jack (or a universal rolling jack with a platform); socket and wrench set; paint or marker for marking; 1 L (1.1 qt) container for draining oil; torque wrench

Part

  • 🔩 Rear axle differential (rear drive unit) assembly. OE numbers GM/Opel: 42550050, 42550055, 95273423 (and other interchangeable variants). Differential oil: 75W-90 GL-5 (synthetic gear oil, about 0.65 L (0.69 qt))
There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes and 3 more. See manuals →

Step by step

20 steps
  1. Raise the vehicle on a lift, or position it over a pit, with the rear axle on supports (the wheels must hang free). Make sure the vehicle is securely held.
  2. Place a container under the differential, remove the drain plug (3/8-inch square drive), and drain the oil from the differential. Reinstall the plug.
  3. Disconnect the driveshaft (propeller shaft) from the differential flange: remove the 4 mounting bolts and move the shaft aside (tie it up with wire or a zip tie to the body so it does not hang).
  4. Disconnect the electrical connector of the AWD electromagnetic coupling (located on the differential housing).
  5. Disconnect the rear axle shafts (halfshafts) from the differential flanges: remove the mounting bolts and move the shafts aside (there is no need to remove them completely; it is enough to free them from the differential).
  6. Place a transmission jack (or a rolling jack with a wide platform) under the differential and raise it slightly to take the load off the mounting points. Securely strap or chain the differential to the jack. The unit is heavy, and dropping it is dangerous.
  7. Using bright paint or a marker, outline the front differential mounting bracket on the body. This will help you position the new differential exactly in its original location during installation.
  8. Remove the two rear bolts that secure the differential mounts to the subframe (tightening torque on installation: 108 N·m (80 lb-ft)).
  9. Remove the front bolt that secures the differential to the body (tightening torque on installation: 100 N·m (74 lb-ft)).
  10. Slowly lower the jack and pull the differential out from under the vehicle. Inspect the old unit for housing cracks, signs of oil leakage, and the condition of the rubber mounts.
  11. Place the new differential on the jack and raise it into position. Align the front bracket with the outline you drew on the body.
  12. Start all three mounting bolts (two rear bolts on the mounts and one front bolt) by hand, but do not tighten them yet.
  13. Make sure the front bracket lines up exactly with the marks, then tighten the rear mount bolts to 108 N·m (80 lb-ft).
  14. Tighten the front bolt to 100 N·m (74 lb-ft).
  15. Remove the jack from under the differential.
  16. Reconnect the electrical connector of the AWD electromagnetic coupling.
  17. Install the rear axle shafts onto the differential flanges and tighten the mounting bolts (check the torque in the service manual; typically 30-40 N·m (22-30 lb-ft)).
  18. Install the driveshaft onto the differential flange and tighten the 4 mounting bolts (torque 25-35 N·m (18-26 lb-ft); check the exact value in the manufacturer's service manual).
  19. Remove the differential fill plug (3/8-inch square drive, usually located above the drain plug). Add fresh 75W-90 GL-5 oil through the fill hole until oil starts to run out (capacity about 0.65 L (0.69 qt)). Reinstall the fill plug.
  20. Lower the vehicle, start the engine, and drive 10-15 km (6-9 miles). Check for oil leaks, unusual noises, and any all-wheel-drive system error messages on the instrument cluster.

Common mistakes and warnings

  • The rear axle differential on the Opel Mokka (GM Gamma II platform, shared with the Chevrolet Trax and Buick Encore) has a known problem with corrosion of the aluminum housing, which leads to cracks and oil leaks (GM TSB 18-NA-049). Do not drive the vehicle with a humming or leaking differential. Coupling lock-up at speed can lead to loss of control. After replacing the differential, programming of the AWD coupling control module at an authorized dealer is required in some cases (adaptation of the new DEM module). If the "AWD Service" light stays on after installation or the all-wheel drive does not engage, take the vehicle to a shop with GM Tech2/MDI diagnostic equipment.