My mechanic noticed this leak at my last oil change - it seems to be the same issue described in these threads: http://www.e90post.com/forums/showthread.php?t=804568&highlight=front diff leak http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2576277 Unfortunately my car is now out of warranty despite it's extremely low 23000 mileage. I don't have a jack so I couldn't get a nice picture from under the car, but I did manage to get some shots from inside the wheel wells. You can see how the left side kinda looks wet compared to the right side which is nice and dry. Local BMW-only indy shop quoted the repair at $300 total. I think it's just part #6 on this diagram I need? http://www.realoem.com/bmw/showparts.do?model=VC93&mospid=49549&btnr=31_0718&hg=31&fg=15 The actual part itself is really cheap but it seems like a real task getting to it. How bad do you guys think this looks? Neither of the auto shops I spoke to seemed particularly concerned about it. I've been thinking about simply topping off the differential fluid and seeing if I can hold out until Inspection I to take care of it. Is this a particularly pesky issue with xDrive models?
This is quite a common issue on the e90. It's not super easy. You have to remove the axle which requires the control arm to be removed. Make sure your input seal to the front diff is not leaking that is also common. But as long as you keep fluid in the diff it won't be a issue.
I'd check the differential fluid level and make sure it's not been over filled. Sometimes the fluid level gets too high [thanks, JiffyLube] and fluid will leak past the seal just until it gets back down to the correct level. If you check the level and it's fine or close to fine, I wouldn't spend any money. Check it again soon to see it it changes. Doesn't take much seepage to LOOK like a leak.
Well my car only has 23000 miles on it despite its age so the fluid that's in there right now is just what came in it from the factory. I'm thinking of just having a local indy drain and fill the front diff with new fluid. This way we can see how much comes out vs how much goes in and see where to go from there...if it's not a bad leak then I'll just make it an item to take care of at the 30K Inspection I service. So one question I have is: does the car throw a code or light or something when the diff fluid gets low? Or do I have no way of knowing until the diff basically burns itself out?
There is no level sensor for the diff it will just damage the diff if the fluid goes low. Make sure you check the level often to track the leak.
Really smart advice. There is less than a pint in the front diff, so 30K is not a good interval to use for checking.
I didn't mean 30K as check interval I mean to hopefully last 6000 miles until I hit the 30K bundle of stuff I have to get taken care of. Is there anything else I might as well have them replace as well when they go and take everything apart to get to the shaft seal?
So I went and got my front diff fluid changed out today and asked the mechanic to clean the area up as well. Looks good so far but I'll be keeping an eye on it. The tech did say that he drained out pretty much exactly the same amount as he put in, so I guess the diff hasn't really lost much fluid at all.