DCT Fluid leaking

[M'EM]

Hey All,

I returned from a 10 day vacation to find a puddle of fluid on the garage floor. I assumed it was an oil leak as my car previously had a small leak from the drain plug on the smaller sump. So I assumed it had gotten worse and started to leak profusely. I poured in 1/2 a quart of oil and started to drive the car and then got the Transmission Malfunction error and the car started to skip a few gears and acted weird. That had me thinking may be its the transmission fluid that was leaking. I jacked the car up and of course see the whole plastic cover wet and oil dripping from the surface of the pan (see attached Pic).



Searching on the forums there are multiple threads of members having similar issues and the resolution is as simple as replacing the Pan or as bad as replacing the whole Transmission . Further search also led me to a post about replacing the Mechatronics harness Oring...

https://www.m3post.com/forums/showth...t=Mechatronics

which honestly looks like a tough DIY to do...

I did do a DCT service at 80,000 miles where I replaced the filters, fluid, orings etc. I am not able to recall if I replaced the Gasket and the Pan itself...

Currently Car is at 122,000 miles.

So Question is how do I know for sure where the leak is? I am thinking of doing a full DCT service and replace the Pan, Gasket, filters, Orings, Caps, clips etc along with the fluid but I would hate for me to do all that only to find the Mechatronics unit failing or the Mechatronics oring has failed...Any sure shot way of finding what the issue is and in general where would you start?

[spammysammich]

You have to hose the whole pan area down with brake cleaner and run it on a lift until it gets up to temp. Hold rpm at 2k rpm for a couple minutes. Check the pressure filter cap, the o-ring flattens out as it ages and starts pissing pentosin out. It sometimes seals itself as the transmission heats up but until then you’ll lose a tablespoon if it’s leaking from the cap.

[spammysammich]

Get a fiber optic borescope and get a visual on the mechatronics connector

[spammysammich]

Also, you could try putting fluorescent dye in the transmission fluid and trace it with a uv light.

[M'EM]

Ok will try what you have suggested.

I am looking at this borescope:

https://a.co/d/csbXZEo

Is this good or do you have any recommendations?

Also where do I look for with borescope to check the mechatronics connector?

[Scrippy]

It’s not always the pan. The mechatronics gasket as well as the O-ring for the harness at the top of trans can leak as well. I’d take that prior advice and clean and see where the leaks start at. Get car up and use a diluted simple green spray with a pan underneath. Wipe away all that you can and the start the car and let it warm up for a while. The top Oring usually shows a leak with use on the road. The fact it was parked and leaked kinda does make me think pan or mech.

[M'EM]

Thanks. So I did what you guys suggested. I cleaned the pan and surroundings. The car has not been turned on for a few days so there was no active leak. I then started the car and while it was idling to get to operating temp it started leaking and there was a small puddle (about a couple of table spoons) on the floor. See the recording below:

I then revved the car to 2k for lil over a min and placed a camera underneath to see what was going on. See recording below:

In my opinion it looks like the leak is from the pressure filter cap area and it leaks more profusely when the car was idling to the temperature and then the leaked slowed down when I was revving it. My guess is if the source of leak is from the mechatronics unit it most likely would have leaked from somewhere else, correct? Can you guys look at the recordings and share your thoughts?

As always appreciate your valuable feedback.

Also I pulled the codes, it shows 5A41 - Pressure Sensor Clutch 1: Total failure. I assume it got triggered due to low fluid level and will go away once I fix the leak and refill fluid, fingers crossed.

[spammysammich]

Ask me how I know it’s your pressure filter cap o-ring. Never reuse them, not saying you did. But I’m sure somebody out there has or will try to.

[RocketyMan]

Originally Posted by spammysammich

Ask me how I know it’s your pressure filter cap o-ring. Never reuse them, not saying you did. But I’m sure somebody out there has or will try to.

Looks like an oring made of Spammy's favorite rubber material, buna.

I bet there is an FKM upgrade to get.

[spammysammich]

My 9th circle of hell will be made of that bullshit.

[RocketyMan]

Originally Posted by spammysammich

My 9th circle of hell will be made of that bullshit.

Lol! Come on!...

Do you know the dimensions/size of the oring? An upgraded oring might be in everyone's interest if we were to learn about the size.