BMW X3 (F25) Front Diff Seal

Afternoon,

Thought I would post on here in case anyone has come across this before.

Farther in-law recently purchased a 2012 X3 2.0 X-Drive via private sale.

I gave it a once over and a service and found the front diff to be leaking, I drained the remaining fluid (only around 100ml or so) filled and cleaned, so we could see where the leak was originating from.

The leak was quite major, from the nearside output shaft seal.

I ordered a replacement (Febi) and replaced - not to difficult of a job, thought we were all said and done, but it started leaking again after a few days.

Cant help but think the previous owner would have known about this - but its my job to get it sorted now.

The seal that I put in went really well, so Im now struggling to think why it may have failed.

So far my thoughts are that it may be the output shaft that's killing them, although it looked fine, or some kind of fracture in the diff casing.

I ended up swapping the diff.

Managed to find a used item for £300 - swap took around 5 hours.

I stripped the old unit to find the plastic / nylon bearing cage on the leaking side had cracked / split.