DIY: Fix the DCT Fluid Weeping Problem (Mechatronics Harness O-Ring)

[Redd]

Originally Posted by spammysammich

You sure that isn’t due to sample size? How many E9X M3 are there in Malaysia? Previous owner said mine was leaking at around 80k miles and took care of it.

That's possible. I certainly haven't gone and studied the market entirely. Lol. My mech is one of the most popular E9x M3 mechs in town and majority of the E9x M3 owners go there. But he says he's never had to change the DCT mecha seal ever.

[active_m]

Originally Posted by marauder1

Wow you all did this with the trans in the car. I took the transmissions out to change the gasket. Did the mechatronics cover and oil pan at the same time. I wouldn't image doing this on jack stands with the trans in. Pulling the trans was easy except for the 2 bolts on the 10 and 11 oclock positions due to the heat sink for the dct oil cooler.

Yeah it wasn't ideal doing it on jack stands, but without a lift and refusing to pay someone to do the work I had to get it done one way or another.

[spammysammich]

Originally Posted by active_m

I removed the drive shaft, transmission cross member, and exhaust and was able to tilt the trans enough to where I could remove all the hardware for the side pan and slip it out. It does help if you have medium sized hands for sure though because it does get tight towards the top of the trans tunnel. A long 1/4 ratchet and good lighting will be your best friend to get this done. I also replaced the mechatronics O-ring which is probably the hardest thing to do without dropping the trans. All this was done in the evening after work for two days so about 4-5 hours total time granted I did it all on the floor on my back.. here's some pics of the before and after.

On quickjacks or jack stands? Tilting it to get to the top screws seems like a good way to go.

[Nefer]

Originally Posted by Benjiman

Massive thanks OP, just completed this on my 335i DCT. It was a pain in the arse but do-able, I also lowered the front sub frame a little to get even more room above the trans to work. I'd defo go through it again rather than take it somewhere to be done.

spammysammich I think the mechatronics gasket is do able without removing the trans, by lowering the front subframe a bit, you could probably get it to tilt a bit either way based on how you lower the subframe.

I found a shop in Bristol UK that says they do the right side mechatronics gasket without removing the trans, they do how ever remove the trans to do the O-Ring from the OP.
They call it their stage 2 service, check out their video on youtube

You can see that they have the cover off whilst trans still in around 2 minutes 10 seconds.

That is where I got the idea to also lower the subframe to give some extra room.

Hey, could you share steps to lower the subframe - I'm struggling to get it low enough to expose the mechatronics lid fully. I've un-bloted the 6 carrier bolts to the main frame and left them loose while the subframe is jacked-up, but when I undo the jack the engine+subframe just start to hover magically. I was hoping it would go down a lot more but something's preventing it from going further down. I did the trick with tilting the trans to change the O-ring but it was not enough to remove the mechatronics cover. Help!