2011 135i m package n55 7 speed automatic dct

[Joe Daddy]

What can I do to remove all the fluid from my DCT transmission after the transmission cooler failed and put antifreeze into the transmission and transmission fluid into coin system? It had less then 100 hundred miles pu on it before I noticed.

it’s quite a mess and I haven’t found anything online. That really helps with this situation..

I have another concern that possibly the coolant getting into the transmission fluid, overfilled the transmission and forced fluid where it’s not supposed to go and if that’s the case, would I overfill it with hypothetically, seafoam transmission, tuner cleaner, and running briefly through the system?

I know it will be expensive no matter which route I go due to the fact of changing filters and fluid multiple times or should I start the dreaded transmission, tear aparrt and clean? If anyone has had this happen or knows what to do in this situation, please let me know.

[Greydog]

Morning Joe

Been there not a nice place to be with huge quotes from Dealer (new trans £5k ) and Specialist (rebuild  £2.5k) I decided to spend out on Fluid and filters to see if I could flush it through.

I used a technique that worked on Volvo's here it is for what it's worth and it works

First drain and refill the transmission (Tip make sure you can undo the fill plug before you drain it) I brought enough Fluid for 2 flushes and a refill plus 2 filters 

After the initial refill run the engine and go through the normal gear selection routine. The next part you will need some clear hose that will fit onto the return pipe from the transmission cooler (the rear one on your transmission I believe) and a clearish plastic container so you can see what's in it, I used a windscreen wash  container and put a mark on the side at around 3ltrs, now with the help of an assistant run the engine watch the fluid going into the container at the mark engine off and replace the return pipe empty the waste fluid into a disposal drum I have an old 5 gallon drum. Then repeat two more times, the last time don't refill drop the pan and change the filter make sure you can catch any fluid left in the pan.

By now with 6 or 7 litres through the box you should have flushed the Torque converter as well. Now repeat the process all fluid should now be looking pretty new but I didn't cut corners this time 4 flush throughs. The last same routine don't fill drain the pan of the last fluid, drop it and change the filter. Put it all back together and refill run it up to temp and check the levels and your done

In my case it was the Transmission on my E53 4.6is it has covered more than 50k since still smooth in operation. I use this method when carrying out a gearbox service these days a little more expensive fluid than (not changing filters twice just once) a drain and refill but always clears the torque converter.

Good Luck hope this helps

Dave