[zanchee]

Hey all,

I'm buying a 2019 BMW M2C and I've been going over the car as part of my pre-purchase inspection. Everything looked great until I pulled the panel off that covers the transmission. It looks like there is a leak.

My friend and I were having a hard time trying to diagnose what the issue could be. Wondering if anyone has some ideas/thoughts/suggestions

It looks to me like all the oil is downwind from the drain plug. Checked and it was definitely tight. Wondering maybe if it's a bad rubber seal/crush washer.

All this to say, really trying to figure out what best case/worst case scenarios are in order to effectively purchase this car.

[jefe2000]

Looks like 6MT, not a DCT. There are no rubber seals or metal crush washers on the fill/drain plugs on these transmissions. It’s just a metal plug to metal case seal.

From the photos, it definitely looks like the drain plug is leaking. Maybe the plug is damaged in some way and not sealing properly? The plugs are pretty inexpensive to replace: https://www.fcpeuro.com/products/bmw...ug-23127602815

[Track/S]

If the car doesn't make any noise, you can drain the oil and check how much it has, if it doesn't need much you can buy it, change the oil and put a new drain plug.

Before draining the oil, clean the drain plug with a brake cleaner and take a good look at it, there are no cracks around the plug.

[zanchee]

Thanks for the replies!

Took a closer look and couldn’t see any oil coming down the side, so don’t think it’s the shaft seal. It’s in with BMW now, we shall see what they say.

[zanchee]

They feel pretty confident it’s just a bad transmission plug. 👍 Thanks for helping me diagnose!

[zanchee]

Well… I drained the oil replaced the plugs and drove it for a few weeks. Looks like the plugs aren’t the issue.

[David.m]

Originally Posted by zanchee

Well… I drained the oil replaced the plugs and drove it for a few weeks. Looks like the plugs aren’t the issue.

in those photos, looking front to rear, the oil looks to be coming down the rear right side of transmission case (fill plug is on left side), the problem may be the transmission output shaft seal.

[zanchee]

Originally Posted by David.m

in those photos, looking front to rear, the oil looks to be coming down the rear right side of transmission case (fill plug is on left side), the problem may be the transmission output shaft seal.

I just picked up some UV oil dye, so gonna clean it up well and add some dye.

What you’re saying sounds like the next probable cause.

[zanchee]

Originally Posted by zanchee

I just picked up some UV oil dye, so gonna clean it up well and add some dye.

What you’re saying sounds like the next probable cause.

David.m

Any resources you got for changing the output shaft seal? I can’t seem to find anything on forum for this. Feels like it might be a tough job otherwise. 😜

[David.m]

Originally Posted by zanchee

David.m

Any resources you got for changing the output shaft seal? I can’t seem to find anything on forum for this. Feels like it might be a tough job otherwise. 😜

afraid I'm no help with the repair, hopefully it can be done by dropping the tailshaft rather than the trans! Probably worth a search/post on the F80/82 forum as we're all running the same transmission.