Differential leaking from output shafts

[Fried_Chicken]

I had to do some work on the car and while I had it lifted I checked the rear, looking for a clunk I have but still wasn't able to find it.

Unfortunately the differential was leaking so much fluid it actually had a droplet at the bottom, so not a simple weep. I'm pretty sure the source of the leak is the output shaft seals (the input seal is fine), although it could be the gasket holding the two together? That part is afaik discontinued.

Maybe the same thing happened to me that happened to Dave:
http://www.zhpmafia.com/forums/showt...since-changing

I'm seeing two different part numbers depending on the diagram:
Part 14 here:
http://bmwfans.info/parts-catalog/E4..._drive_output/
Part 8 here:
http://bmwfans.info/parts-catalog/E4...ve_gasket_set/

If I go for a rebuild or something like that, is there any "while you're in there" stuff I should consider?

[Fried_Chicken]

I got the differential seals, but now I'm second guessing my initial diagnosis b/c I'm an idiot.

I think the output shafts *were* leaking, but now as I'm installing the new ones, I feel there's a real possibility they will start leaking. The culprit was likely the differential cover gasket. It's my understanding MW discontinued this part, or maybe not, since I see it available here:

https://www.turnermotorsport.com/p-5...uine-bmw-part/
and here:
https://www.turnermotorsport.com/p-3...-cover-gasket/


I'm now starting to think I have to pull the differential out to do this right, and to do the main cover gasket, I'm going to need RTV skills.

That said, there was plenty of oil in the diff, so the leak wasn't bad. Hopefully I can get the output shaft seals in correctly, and I won't have introduced a leak, and I can leave it. So far I'd say this was overall completely stupid.

[GeorgeH]

Pictures of your leak(s)?

Its been my experience that because the diff oil is soooo sticky that it will look a lot worse than it really is. Like, you might see a drip, but it will not actually fall of and just stay a drip with know real noticeable change in level.

*Also, I've never used a gasket on dozens and dozens of diffs, never an issue. Stand the diff on the pinion and remove the cover. Clean the sealing surfaces and apply a light smear, torque to spec and you'll be fine.

[Fried_Chicken]

Pictures of your leak(s)?

Its been my experience that because the diff oil is soooo sticky that it will look a lot worse than it really is. Like, you might see a drip, but it will not actually fall of and just stay a drip with know real noticeable change in level.

*Also, I've never used a gasket on dozens and dozens of diffs, never an issue. Stand the diff on the pinion and remove the cover. Clean the sealing surfaces and apply a light smear, torque to spec and you'll be fine.

When I draind it there was *plenty* of oil in the diff, so you're right lol. I did have a droplet at the bottom of the diff though. I think the diff didn't like towing 3k lbs, which is unfortunate b/c that's what it should be rated for.

[John in VA]

Also, I've never used a gasket on dozens and dozens of diffs, never an issue. Stand the diff on the pinion and remove the cover. Clean the sealing surfaces and apply a light smear, torque to spec and you'll be fine.

George, a light smear of what?

[GeorgeH]

George, a light smear of what?

Sorry, RTV. I use Permatex Ultra Grey.

[John in VA]

Sorry, RTV. I use Permatex Ultra Grey.

Thank you!

[Fried_Chicken]

*Also, I've never used a gasket on dozens and dozens of diffs, never an issue. Stand the diff on the pinion and remove the cover. Clean the sealing surfaces and apply a light smear, torque to spec and you'll be fine.

I need to stop thinking in terms of BMW reality, and get back into the real world. Although BMW did discontinue the gasket, so maybe they agree.

[Fried_Chicken]

Got the diff apart, cleaned, gasket maker put on, diff cover bolts torqued to 33 ft. lbs. Now it's sitting, I'm having a lunch break, and then I'll do the output shaft seals (properly this time). Hopefully I can get the diff back in the car today and either refill it tonight or tomorrow morning.

I'm adding some Liqui-Moly MOS2 stuff for gears.

[Fried_Chicken]

The old gasket was definitely shot and leaking.