Transmission Output Shaft (6MT) Leak - Fluid Choice?

[BikeNHV]

Hi All,

Had the dealer perform some SULEV warranty work (N51), and they gave me a list of other items that should be addressed. Some I knew about (oil pan leak), and some I did not.

The issue in question is a small leak from the transmission output shaft. Car has just under 137k miles.

I am using Redline MT-LV fluid, which is a lower viscosity than the OE fluid.

Is the output shaft seal a common failure point for the Getrag transmission?
If not, I'm wondering if swapping back to the OE fluid may be wise.

[Thunderguts]

I've heard it's a common failure. If it's small enough, I guess wait until you need a new clutch. Fluid likely won't make much difference. It's just going to fail over time.

Just wait till you find out how common leaks are after replacing them! Supposedly there's room to hammer a new one in and scoot the old one back towards the block. That would give you double seals and maybe prevent it from leaking.

[spidertri]

They said it's definitely the transmission output shaft seal and not the shift shaft seal?

All of my manual trans BMWs have had to have the shift shaft seal replaced at some point and it's right above the trans output shaft so it drips down coating everything below it.

[BikeNHV]

Thanks guys. Looking at this again, the quote says "output shaft" but the inspection video they sent identifies the shift shaft.

So that's definitely less bad, and far more expected particularly at this mileage.

I think I'll swap the trans fluid and address the oil pan leak first. It's nearly impossible to monitor severity of other leaks as long as the oil pan is spraying everywhere.
The dealer identified some oil soaking on the transmission mounts which I'm willing to bet traces back to the oil pan, not a transmission leak.

For the shift shaft, adding a second seal is definitely an option, that said doing it right doesn't seem like all that much more effort.
And I agree, more serious work like the output shaft is better done with the transmission out for a clutch job. I'm on the original clutch so that's always a "could happen" job.

[spidertri]

Okay cool, glad to hear it's not the trans output.

I had to do the shift shaft seal on my 128i a couple years ago. I tried the double up trick prior to that and it made my leak worse, but i think that could have been due to my original seal being messed up and not allowing the new one to seat correctly.

I did a mini write up on how to get to it and I ended up replacing the giubo at the same time. It's also a great opportunity to refresh all of the shifter bushings and throw in a N54 shift lever if you haven't already.

https://www.1addicts.com/forums/show...29&postcount=4

[BikeNHV]

Cool! Yeah, I did already stumble across your write-up. Definitely not too bad.
And I agree, great time to also do an upgrade/refresh.

I do still think I'm going to wait until after the other couple of items I mentioned. Thinking of the "what if" between now and then I end up needing a clutch, might as well take care of all these items with the trans out.