Leaky rear differential

[M3 Driver]

the oil is on the concrete/garage floor under the diff.

[ATB88]

the oil is on the concrete/garage floor under the diff.

Well then, again, it's going to be one of the three seals. You should be able to figure out which by getting under the car and looking at the input and both output flanges, and see which ones have a trail of fluid coming out of them.

[bigjae46]

Probably the input seal. No cost benefit to doing all 3 while there unless you just want to do it.

[M3 Driver]

i finally got a opportunity to inspect this leak and it is originating from the input shaft seal. what is the street price for this repair? the diff does not have to be dropped and the seal is prolly $30. yeah, i have to get the OEM fluid which is a rip.

[TexaZ3]

i finally got a opportunity to inspect this leak and it is originating from the input shaft seal. what is the street price for this repair? the diff does not have to be dropped and the seal is prolly $30. yeah, i have to get the OEM fluid which is a rip.

if you have not done this job, I suggest you pay somebody to do it. its not bad, but its not something that you just knock out one day after dinner.

[M3 Driver]

yesh, i plan to have a pro do the work.

i need to clean it up as there is oil on the underbelly. i suppose the pinion spun it around the area. i don't have any ramps or i would go to a car wash bay and put the rear wheels up and spray it down. how effective will it be if i simply lay down on the deck and attempt to powerwash the area? i can degrease then use soap. diff oil drys thick.

[eacmen]

yesh, i plan to have a pro do the work.

i need to clean it up as there is oil on the underbelly. i suppose the pinion spun it around the area. i don't have any ramps or i would go to a car wash bay and put the rear wheels up and spray it down. how effective will it be if i simply lay down on the deck and attempt to powerwash the area? i can degrease then use soap. diff oil drys thick.

If you lost alot of diff fluid you should probably top it off before driving it to the shop or tow it.


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[M3 Driver]

estimate is as follows - $530 for only the input shaft seal replacement, that includes pinion seal, locking flange and exhaust gaskets

[maw1124]

You’ll do pinion seal leaks multiple times on these cars... cost of doing business... worse if your car sits... the dead weight is tough on the seals where the weight sits... ask me how I know.

maw

[mrgizmo04]

estimate is as follows - $530 for only the input shaft seal replacement, that includes pinion seal, locking flange and exhaust gaskets

Yeah, unfortunately it's a bit pricey because you have to make a path to it by removing parts of exhaust, heat shield, driveshaft etc.

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[clawhamm3r]

You’ll do pinion seal leaks multiple times on these cars... cost of doing business... worse if your car sits... the dead weight is tough on the seals where the weight sits... ask me how I know.

maw

I started another thread here a few weeks back on this topic. Did mine 6 years/23k miles ago. But in the last 2 years put maybe 1k miles on the car and guess what's leaking lol.

I ordered a new seal from FCP euro and it actually came with two of them in the BMW packaging. BMW knows how shitty these are so they're throwing in extras now lol?

[M3 Driver]

today i need to decide whether to reseal the entire case (input/output/cover) or simply the present problem which is the input seal. i do't have a price for the larger job just yet. it is a 2005 with 80K miles and the diff has the factory seals and bushings..

[eacmen]

today i need to decide whether to reseal the entire case (input/output/cover) or simply the present problem which is the input seal. i do't have a price for the larger job just yet. it is a 2005 with 80K miles and the diff has the factory seals and bushings..

Someone can correct me if I am wrong, but I think the input seal is the most labor intensive. I think the others can be done with the diff on the car without taking the heatshield down. I never actually did them myself yet though. I wouldn't think the output seals would add much labor onto the job and might be easier on the tech since the exhaust would be out of the way already.

[clawhamm3r]

It can all be done in the car but at the point you're disconnecting everything to do it all in the car I'd just do the three extra bolts to drop the diff. A lot easier to do the seals out of the car.

I've only done the input seal in the car while in the car, it's a lot of stuff to get out of the way. I've heard you can just bend the heat shield and push the exhaust and driveshaft out of the way. If my quick jacks ever get here I'll do my input in the car this time, and I'll try to take the shortcuts and report back lol.

[heinzboehmer]

It can all be done in the car but at the point you're disconnecting everything to do it all in the car I'd just do the three extra bolts to drop the diff. A lot easier to do the seals out of the car.

I've only done the input seal in the car while in the car, it's a lot of stuff to get out of the way. I've heard you can just bend the heat shield and push the exhaust and driveshaft out of the way. If my quick jacks ever get here I'll do my input in the car this time, and I'll try to take the shortcuts and report back lol.

You can also drop the diff if you just undo the sway bar bushing brackets, the driveshaft, and the output shafts. The heat shield has an access hole to get to the drive shaft bolts and you can undo the front diff bolt by moving a couple plastic bits out of the way. The rest of the stuff is easy to get to.

Might be a shorter shortcut than trying to do the seal with the diff in the car. I dropped it once like this before when I was feeling lazy and it went pretty fast.