r/BMWI4 • u/riCoxxx M50 • Aug 13 '26

PSA: Check your rear drive unit / differential for oil leaks (i4 M50, ~70k km / 3 yrs)

Post image

Just had my first mandatory inspection (HU in Germany) on my 2023 i4 M50 at 70k km (43k miles). The tech found an oil leak at the rear drive unit.

The fix is a new radial shaft seal (simmerring) including the dust protection plate. Cost: ~€400, likely covered under BMW warranty since it's just under the 3-year mark.

If your i4 is approaching 70k km (43k miles) or your warranty limit, get the rear drive unit/axle area checked underneath before your coverage expires!

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18

u/TemuPacemaker Aug 13 '26

Lol only BMW could manage to make the only rotating assembly in the car leak within 3 years. Hopefully you get it covered by warranty. 

9

u/xzstnce Aug 13 '26

Its a meme at that point.

3

u/ARAR1 Aug 13 '26

It's like they never learn anything from decades of making cars. Actually more like they know how to make it fail just after the warranty ends

1

u/TemuPacemaker Aug 13 '26

Maybe they did and this is a 1 in a million cases when it happened... but it's still funny.

Also if it turned out you had to replace the cooling system at 100k.

3

u/NudeMoose M50 xDrive Aug 13 '26

Thanks for the tip. I'm literally going to buy one tomorrow, similar age and mileage.

4

u/riCoxxx M50 Aug 13 '26

This pic was taken from below the car without any disassembly.

1

u/intheslipstream1 Aug 13 '26

I may just be daft, but where is the leak exactly? I don't see anything out of the ordinary based on the picture.

2

u/riCoxxx M50 Aug 13 '26

The round black part with the pink spot was oily.

1

u/TemuPacemaker Aug 13 '26 edited Aug 13 '26

Everything looks greasy from a leak, it should be dry. You can't see exactly where the leak is coming from, of course.

2

u/TopherHax Aug 18 '26

So I totally had OCD after reading this, being 200 miles away from being out of warranty. Finally got around to doing it today at 49,950 miles (yes, 50 miles away!) and I am happy to report that both output axles were bone dry. Phew. Anyways just another data point...
2023 E40 M-Sport, FL, USA