335xi Front Differential Seals DIY???

buly34 · 10-05-2016, 07:59 AM

I noticed a good amount of oil saturation on the bottom of my motor. It doesnt seem to be coming from the oil pan at all. I am 99% sure that it is coming from the front differential seals. Has anyone done this job on an AWD manual e90? I got a quote from a shop to do the work for $1900 including parts and replacing the oil pan gasket at the same time. Any information would be helpful!

Thanks!!!

hassmaschine · 10-05-2016, 08:09 AM

there's really not much oil in a front differential. Are you sure it's not coming from your engine?

BMW has used the same basic front diff/front axle design for ages (over 30 years). I haven't seen too many of the diff seals actually leak. heck, the seals on my E30 are original and it has 270k - they still don't leak!

the N5x however, tends to have issues with leaky oil pans. it just seems far more likely, especially if it's a significant amount of oil.

Anyway, if you're doing the pan gasket, it's probably not much more work to do the diff seals since you have to pull it all apart anyway. I'm having the pan gasket done on our AWD E91 since they have to pull the subframe anyway to replace the steering rack - the shop said it was about 10 hours to replace the gasket otherwise, so I'm saving like 6 hours of labor costs.

buly34 · 10-05-2016, 11:42 AM

Thanks for the info! From looking at it I cant see anything coming from the pan seal. Its all coming from the bottom where the axels go into the differential.

hassmaschine · 10-05-2016, 11:52 AM

yeah, I dunno - there's only like half a liter of fluid in there. If it was that covered in oil, there wouldn't be much left inside. maybe it leaks, but I'd bet a lot of it is coming from the engine somewhere.

anyway, I don't think $1900 is too bad for this job - it hurts the wallet, but it's a hell of a lot of work. I'm paying about $500 over the cost of the other work for mine, but that's only because they already have the subframe & front suspension out anyway. Otherwise I bet it would be closer.

10-05-2016, 07:59 AM	#1
buly34 First Lieutenant 115 Rep 342 Posts Drives: 2007 e90 335xi 6MT Join Date: Oct 2014 Location: Pennsylvania iTrader: (0)	335xi Front Differential Seals DIY??? I noticed a good amount of oil saturation on the bottom of my motor. It doesnt seem to be coming from the oil pan at all. I am 99% sure that it is coming from the front differential seals. Has anyone done this job on an AWD manual e90? I got a quote from a shop to do the work for $1900 including parts and replacing the oil pan gasket at the same time. Any information would be helpful! Thanks!!! __________________ 2007 E90 335xi \| 400WHP // 430WTQ
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10-05-2016, 08:09 AM	#2
hassmaschine Major General 3973 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	there's really not much oil in a front differential. Are you sure it's not coming from your engine? BMW has used the same basic front diff/front axle design for ages (over 30 years). I haven't seen too many of the diff seals actually leak. heck, the seals on my E30 are original and it has 270k - they still don't leak! the N5x however, tends to have issues with leaky oil pans. it just seems far more likely, especially if it's a significant amount of oil. Anyway, if you're doing the pan gasket, it's probably not much more work to do the diff seals since you have to pull it all apart anyway. I'm having the pan gasket done on our AWD E91 since they have to pull the subframe anyway to replace the steering rack - the shop said it was about 10 hours to replace the gasket otherwise, so I'm saving like 6 hours of labor costs.
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10-05-2016, 11:42 AM	#3
buly34 First Lieutenant 115 Rep 342 Posts Drives: 2007 e90 335xi 6MT Join Date: Oct 2014 Location: Pennsylvania iTrader: (0)	Thanks for the info! From looking at it I cant see anything coming from the pan seal. Its all coming from the bottom where the axels go into the differential.
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10-05-2016, 11:52 AM	#4
hassmaschine Major General 3973 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	yeah, I dunno - there's only like half a liter of fluid in there. If it was that covered in oil, there wouldn't be much left inside. maybe it leaks, but I'd bet a lot of it is coming from the engine somewhere. anyway, I don't think $1900 is too bad for this job - it hurts the wallet, but it's a hell of a lot of work. I'm paying about $500 over the cost of the other work for mine, but that's only because they already have the subframe & front suspension out anyway. Otherwise I bet it would be closer.
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