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NHC MOTORS · SERVICE RECORD

BMW 320d GT differential oil leak repair, followed by wheel alignment

Oil and dirt had built up on the rear differential housing of this 2015 BMW 320d GT F34. We removed the differential, replaced the pinion seal and left/right gasket sets, refilled it with PENTA LS 75W/90 and adjusted toe and rear thrust angle after refitting.

Oil and dirt caked onto the differential housing before repair.
Oil and dirt caked onto the differential housing before repair.
2015 BMW 320d GT F34

Oil and dirt were caked onto the rear differential housing of this 2015 BMW 320d GT F34. We removed and opened the differential, replacing the pinion seal and gasket sets on both sides.

After cleaning and sealing the housing joint, we refilled the differential with oil and refitted it. We then measured the wheel alignment and adjusted front and rear toe and the rear thrust angle.

01 / NHC MOTORS

Removing the differential to inspect the shaft and housing joints

Oil can run down a housing or be scattered by a rotating shaft, so the wettest spot outside need not be the start of a leak. We checked underneath, then removed and opened the differential.

Opening the housing exposed its interior and joint faces. Seals and gaskets sit at the shaft and housing interfaces; this repair included the input-pinion seal and gasket sets on both sides.

The removed differential on the workbench, ready to open at the shaft and cover joints.
The removed differential on the workbench, ready to open at the shaft and cover joints.
The interior and housing mating face exposed after removing the cover.
The interior and housing mating face exposed after removing the cover.

02 / NHC MOTORS

Replacing seals and gaskets, then refilling the oil

We replaced the pinion seal, used an insert-nut repair kit and fitted new left and right gasket sets. The condition of the surface a seal contacts matters as well as the seal itself.

After cleaning the housing joint face, we applied Würth RTV sealant and reassembled the cover. Old sealant or oil on the joint can keep new sealant from adhering properly.

We refitted the differential and filled it with PENTA LS 75W/90. New oil marks around the housing or seals, or oil under the parked vehicle, should be checked.

The removed seal and its replacement.
The removed seal and its replacement.
The repaired differential reinstalled under the vehicle.
The repaired differential reinstalled under the vehicle.

03 / NHC MOTORS

Aligning the wheels after refitting

Before adjustment, front toe was 2.1 mm left and 0.2 mm right, a 1.9 mm side-to-side difference. Afterward it was 1.5 mm left and 1.4 mm right, a 0.1 mm difference. Rear toe changed from −0.5 mm left and 0.7 mm right to 2.0 mm on both sides. Toe describes the direction the wheels point when viewed from above.

Rear thrust angle changed from −0.05° to 0.00°. It describes the direction the rear wheels push the vehicle relative to its centerline; it is not the same measurement as toe.

If the steering wheel appears off-center or the car pulls to one side afterward, tell us the speed and road conditions. We can measure again and compare the results with this record.

Before adjustment, front toe measured 2.1 mm left and 0.2 mm right.
Before adjustment, front toe measured 2.1 mm left and 0.2 mm right.
Before adjustment, rear toe measured −0.5 mm left and 0.7 mm right; thrust angle −0.05°.
Before adjustment, rear toe measured −0.5 mm left and 0.7 mm right; thrust angle −0.05°.
After adjustment, rear toe measured 2.0 mm on both sides; thrust angle 0.00°.
After adjustment, rear toe measured 2.0 mm on both sides; thrust angle 0.00°.
After adjustment, front toe measured 1.5 mm left and 1.4 mm right.
After adjustment, front toe measured 1.5 mm left and 1.4 mm right.

Four-wheel toe, before and after on the same car

First screen

Front of vehicle ↑Front left2.1mmFront right0.2mmRear left-0.5mmRear right0.7mm

Front L/R difference 1.9 mm · rear 1.2 mm

After adjustment

Front of vehicle ↑Front left1.5mmFront right1.4mmRear left2.0mmRear right2.0mm

Front L/R difference 0.1 mm · rear 0.0 mm

Rear thrust angle −0.05° → 0.00°

Before and after readings from the same vehicle on 24 August 2026. Vehicle shape and illustrated wheel angles are explanatory, not to scale.

Frequently asked questions

Does oil on the differential mean the whole unit must be replaced?

Not necessarily. The repair depends on the leak location and internal condition. On this car we removed and opened the differential, replaced the pinion seal and both gasket sets, resealed the housing and refilled it.

Does a 0.00° rear thrust angle mean rear toe is zero?

No. Rear toe was 2.0 mm on each side after adjustment while thrust angle was 0.00°. They describe different aspects of wheel direction.

What should I watch for after this repair?

Check for new oil spots where the car is parked or fresh wetness on the housing. For a new driveline noise, note the speed and whether it occurs under acceleration or deceleration.

Differential leak repair with the alignment checked afterward

If your differential is wet, we first identify whether the oil is coming from the pinion, an axle-side joint or the housing seam. We can explain the seals, gaskets, oil and alignment work involved before repair. Mention any oil spots or driveline noise when booking.

We explain the work and estimate before proceeding with your consent.

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031-258-1617 · NHC Motors, Suwon · By appointment

Published 2026-09-26

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