BMW E46 Fanatics Forum banner

1 - 20 of 27 Posts

Registered
Joined
174 Posts
Discussion Starter #1
Long story short I started prepping my car for air ride and as I got under the car I noticed my rear diff LSD is leaking oil 馃槪 Its not leaking bad where it leaves oil on the floor but it is definitely noticeable. Bad bearing seals? Car drives and feels fine, just want to see if anyone here had the same issue. Also if you can give me an idea of how much this issue will cost to fix that'll be great. Thanks!

Note: My car is a 2002 M3 SMG if that helps

Here's some pictures I took today:

919801


919802
 

Registered
Joined
99 Posts
Mine was leaking oil to the point it left a puddle on the floor of my garage when i came home one time. Had it resealed and no more leaks. Problem I had, was we didnt use the BMW Diff oil (at $150 for the 1.5Q you need) and now i get the chatter in parking lots.
 

Registered
E30M3 Race F10 535 R1150Rt M Coupe
Joined
4,163 Posts
Looks like a typical output flange seal leak.
I would also search for the post about checking the differential (m3 forum) vent hole. A clogged vent hole can also cause such.
 

Registered
Joined
324 Posts
Long story short I started prepping my car for air ride and as I got under the car I noticed my rear diff LSD is leaking oil 馃槪 Its not leaking bad where it leaves oil on the floor but it is definitely noticeable. Bad bearing seals? Car drives and feels fine, just want to see if anyone here had the same issue. Also if you can give me an idea of how much this issue will cost to fix that'll be great. Thanks!

Note: My car is a 2002 M3 SMG if that helps

Here's some pictures I took today:

View attachment 919801

View attachment 919802
Not a big deal. Just have the seals replaced on both sides.
 

Registered
Joined
196 Posts
Not a big deal. Just have the seals replaced on both sides.
And then prepare to do it again about 5 years from now... common, repeated failure on these things... my shop found some local seal supplier who had a better rubber seal (they weren't happy with the OEM one, so the second time around we went another direction)... it's worse if your car sits a lot, which mine does... GL.

maw
 

Registered
Joined
174 Posts
Discussion Starter #6
Thanks for the info guys, will pick up a seal kit for the differential and will probably just change it all at the same time! (y)
 

Registered
Joined
324 Posts
And then prepare to do it again about 5 years from now... common, repeated failure on these things... my shop found some local seal supplier who had a better rubber seal (they weren't happy with the OEM one, so the second time around we went another direction)... it's worse if your car sits a lot, which mine does... GL.

maw
Meh. My replacements have lasted over ten years....
 

Registered
Joined
196 Posts
Good stuff... I think sitting a lot caused mine to leak in the one spot where the diff sat... that's on me I suppose... no biggie.

maw
 

Registered
Joined
324 Posts
Thanks for the info guys, will pick up a seal kit for the differential and will probably just change it all at the same time! (y)
I would consider just changing the fluid and using the BMW friction modifier. Clean the case, etc., and drive the car. Chances are the seals will readjust. If not all you've lost is the time to change the fluid...you could probably reuse the new fluid when you replace the seals.
 

Registered
Joined
174 Posts
Discussion Starter #10
I would consider just changing the fluid and using the BMW friction modifier. Clean the case, etc., and drive the car. Chances are the seals will readjust. If not all you've lost is the time to change the fluid...you could probably reuse the new fluid when you replace the seals.
Hmmm I like this idea a lot better since I can do this myself, if it still leaks then I'll replace the seals through an Indy shop.
 

Registered
Joined
4,590 Posts
And then prepare to do it again about 5 years from now... common, repeated failure on these things... my shop found some local seal supplier who had a better rubber seal (they weren't happy with the OEM one, so the second time around we went another direction)... it's worse if your car sits a lot, which mine does... GL.

maw
Why M3 diff output seals leaking is common while non-M cars seem don't have this issue? Cannot be just the seal material.
 

Registered
Joined
196 Posts
Why M3 diff output seals leaking is common while non-M cars seem don't have this issue? Cannot be just the seal material.
I don't have an answer for this one... I can imagine the M3 diff being beefier and heavier, the stance putting more pressure on the seals, and the seals themselves being common to all E46 cars... but those are just guesses... I've confirmed none of it... maybe those paying more attention can chime in.

Cheers,

maw
 

Registered
Joined
4,590 Posts
I don't have an answer for this one... I can imagine the M3 diff being beefier and heavier, the stance putting more pressure on the seals, and the seals themselves being common to all E46 cars... but those are just guesses... I've confirmed none of it... maybe those paying more attention can chime in.

Cheers,

maw
Loading or power should not affect the sealing surface, except output shafts speed; but I don't think M3 speed is the reason. I think M3 might have more shaft radial and axial plays than non-M, causing the seal to leak sooner.
 

Registered
Joined
196 Posts
Don't forget the weight of the differential itself... the rest of what you said is the same as what I said... I purposefully didn't mention power output... stance (your "radial and axial plays") + weight of the differential... but again, I'm guessing... "why?" is irrelevant to me... I don't own a non-M.

maw
 

Registered
Joined
324 Posts
Don't forget the weight of the differential itself... the rest of what you said is the same as what I said... I purposefully didn't mention power output... stance (your "radial and axial plays") + weight of the differential... but again, I'm guessing... "why?" is irrelevant to me... I don't own a non-M.

maw
I would argue the weight of the diff is irrelevant; it's hung on the subframe. The only weight on the seal(s) are the axles/joint at the diff. There may be axial play in the axles but that play is NOT xferred to the diff...the joint at the diff side of the axle bolts to the flange, but the axle itself is free to move outside to inside, indeed as the IRS operates.

I suspect the diff output flange finish, seal material and time and chemistry of the diff fluid is more to blame.
 

Registered
Joined
196 Posts
Aren't the seals and fluid the same as nonM though? I hadn't thought about "why" until now, but now that it has my attention I may as well get clarity.

maw
 

Registered
Joined
324 Posts
Aren't the seals and fluid the same as nonM though? I hadn't thought about "why" until now, but now that it has my attention I may as well get clarity.

maw
Same covers a lot of quality issues...I don't know that the p/ns are the same, I understand the M diffs use a friction modifier, non-Ms don't, who knows.
 

Registered
E30M3 Race F10 535 R1150Rt M Coupe
Joined
4,163 Posts
Why M3 diff output seals leaking is common while non-M cars seem don't have this issue? Cannot be just the seal material.
It's the amount of play in the M3 differential vs the open diff on the other cars. Higher mileage ones have an egregious amount of play with the output shafts.
 

Registered
E30M3 Race F10 535 R1150Rt M Coupe
Joined
4,163 Posts
Aren't the seals and fluid the same as nonM though? I hadn't thought about "why" until now, but now that it has my attention I may as well get clarity.

maw
Seal material same, different sizes/part numbers.
Oil is very specific, from BMW $$$$ many argue, however the argument is price biased.
 
1 - 20 of 27 Posts
Top