Dropping the DCT to fix leaks

[jeebus87]

Anyone done this on their E89? The DCT is leaking from the side seal or the top mechatronic seal, either way it has to come down for repair. Planning to DIY with 4 post lift

Photo of the subject. 27k miles.

[jeebus87]

8 months later, still leaking... sadly still at 27k miles. I just don't drive this thing enough.

Turned out to be a relatively straightforward removal. Easier on a Z4 because the long hood allows reaching the top bellhousing bolts from the engine bay. The abridged version if anyone is going to try this themselves:

1) disconnect battery
2) remove top 2 DCT bellhousing bolts from engine bay
3) remove exhaust
4) remove heatshields
5) remove driveshaft guibo
6) unclip O2 sensors, move cables out of the way
7) remove trans selector shaft bolt and unclip
8) remove drain bolt, drain fluid
9) remove oil cooler lines
10) remove remaining bellhousing bolts (support with tranny jack)
11) remove trans support bracket
12) push trans back, lower gently, and remove electrical harness

I'll update once the parts arrive. I'm planning to replace the electrical connector seal, the mechatronic gasket with new cover plate, oil pan, both filters. All bolts will be replaced (but probably unnecessary). Will swap out the trans mounts. Parts bill was 1.1k.

[B21]

Good write up, thnx👌

Always good to see a well documented repair…hopefully I won’t need this particular piece of guidance..already had plenty of others 🙈

[jeebus87]

Originally Posted by B21

Good write up, thnx👌

Always good to see a well documented repair…hopefully I won’t need this particular piece of guidance..already had plenty of others 🙈

Fingers crossed for you, it's kind of a pain. The M3 forum is littered with posts detailing leaks from the side and top. BMW didn't do a great job sealing these.

[B21]

Originally Posted by jeebus87

Fingers crossed for you, it's kind of a pain. The M3 forum is littered with posts detailing leaks from the side and top. BMW didn't do a great job sealing these.

Oh dear..sounds like a when not if…I saw a few drops of ‘liquid’ on the floor of my new garage ..will have a good look shortly..

[jeebus87]

A little more info for you DIY guys:

Off camera I replaced the side filter and gasket and snap ring. This is part of the FCP Euro ultimate DCT service kit and straightforward to do.

Trans connector sleeve was leaking. There is more info in this post in case you need it https://www.m3post.com/forums/showthread.php?t=1697657. Basically remove the T30 bolt, pull the connector back, remove the (red) seal and replace it with the new seal. Fwiw the new seal was black, some info online suggests that this is an updated part. Part number is 28607849555, runs about $22. Torque is 6 NM for the T30 bolt.



Mechatronic cover and gasket also leaking. BMW recommends replacing the cover which is about $300 (part number 28-60-8-064-572). I'm not sure if this was necessary but I did it anyway. The gasket is 28607842856. I also got all new bolts 28107842829 (x12). Torque for the bolts (M6) is 10 NM. A specific sequence must be followed according to TIS:







I reinstalled the trans. I had to lower the front subframe a bit and angle the engine toward the rear of the car in order to gain the necessary angle to align the bellhousing. This was definitely the hardest part. There are 5 aluminum torque to yield bolts that must be replaced. Part number 23001222893. There is also a specific torque sequencing for the bellhousing bolts:

M8x50 bolts 19 NM
M10 bolts 38 NM
M12x50 bolt 66 NM

Aluminum bolts M12 25 NM + 130 degrees






I still need to torque up the bellhousing, waiting for those Al bolts to come in. Later this week I will replace the oil pan and trans filter, and get the driveshaft bolted back up. All in all, it's been a challenging but fun project.

[B21]

Another well documented write up….very useful…about to have a look at that area on my winter rebuild / update 👌

Great garage..

[jeebus87]

Final update

The aluminum bellhousing bolts have been updated to steel by BMW, and the part number is 23001222893. The M10 bolts are torqued to 38 NM. No angle is needed.

Exhaust can be reinstalled at this time. The heat shield will need to be left off in order to give enough room to pump in the fluid through the fill plug. Luckily there is just enough room to sneak the shields back in at the end with the exhaust in place.

Fluid needs to be pumped in with the car level. Initially about 4L goes in, and then the rest is pumped in during the fluid adjustment procedure using ISTA-D. There are plenty of youtube videos showing this procedure, just know that you absolutely need ISTA-D to put in the right amount of fluid. If you don't use the BMW software you will be about a half liter short. It will be just shy of 7L total.

I think that's about it for the Z4 for now.

[accts4mjs]

Fantastic write up and love the pics (do you have one of where the fill plug is at? Particularly which side?). I'm in the middle of replacing my filters, trans pan, bolts, and fluid and I cannot find the fill plug. Is it behind the heat shield on the exhaust side? Will I need to pull the exhaust off or just pull the shield piece out? Did you just reach in there with a pair of needle nose pliers to pull the nut off the heat shield and is there just the one nut?

Thanks so much!

[jeebus87]

Originally Posted by accts4mjs

Fantastic write up and love the pics (do you have one of where the fill plug is at? Particularly which side?). I'm in the middle of replacing my filters, trans pan, bolts, and fluid and I cannot find the fill plug. Is it behind the heat shield on the exhaust side? Will I need to pull the exhaust off or just pull the shield piece out? Did you just reach in there with a pair of needle nose pliers to pull the nut off the heat shield and is there just the one nut?

Thanks so much!

Hi, sorry for the late reply. Yes, you will need to pull the heat shields off and shimmy them off from behind the exhaust. The trans metal shield is actually held on with two nuts and you need to remove the aluminum heat shields to get to the second nut. The fill plug is on the passenger side toward the rear of the trans.

EDIT: the fill plug is here

[tranquility]

I just marvel at ppl like the OP, how the heck do you know how to do stuff like that? Amazing, props!

Oh, the wheel gap ghost is definitely exorcized from your Z4 haha.

[B21]

My box is now pissing out fluid..not sure where from..got it on blocks and cleaned up..will look tomorrow and see if I can find them..get various faults from the box under hard acceleration ..not good..

[KennyP]

Leaks suck on these cars...
im doing oilpan gasket on 11th september... not pissing oil but is sweating a little...so im getting that fixed... have to remove front subframe, suspend engine from up top and so on... When done i have replaced almost all leak points on n54 engine.. valvecover, filter housing, main seals, now pan gasket. I think oil feed lines for turbos is the only possible leak point then thats still left untouched...

When i had dct pan gasket leak... car did not like hard accelerations and seemed to be like slipping a bit... that was probably because oil level had reduced in the gearbox... these dct-s have to have oil level quite precicely on point... Didnt havee any errors though... just felt a bit odd...
So i sent my car to gearbox specialist shop for DCT service... new oil, filters and pan gasket... that fixed all the issues and the leak.

i think main points are pan, mechatronics seal on the side of gearbox... up top there an o ring that is recommended to replace if you should drop the gearbox even if its not leaking because if it should leak, only way to fix it is to drop the gearbox again... all those should be quite straight forward though labor intensive...
Dont know about input, output shafts... those probably have seals aswell...

Hope its going to be a simpler fix for you...

[jeebus87]

Originally Posted by B21

My box is now pissing out fluid..not sure where from..got it on blocks and cleaned up..will look tomorrow and see if I can find them..get various faults from the box under hard acceleration ..not good..

Well that is certainly frustrating. Keep us updated. Feel free to PM or continue in this thread if you decide to DIY, happy to help.

[B21]

It looks like after cleaning everything thoroughly around the gearbox that the leak (when stationary ..no engine running ) is just from my after market alloy oil pan seal..

Side seal seems dry..can’t see the top seals / wire seal but hoping it’s just the bottom seal

Here’s some photos plus the amount dripped out in 15 hours onto my wooden platform I use for crawling under the car..

I’ve bought a pressure filler and am going to fit a Polish alloy pan today and see if the leaks stop..

Fair amount of damage to under tray plastics so got some alloy and pop rivets to repair some of the cracks ..

[B21]

So dropped the ‘seems leggit’ alloy pan…

The sealing o ring had popped out from its groove so it wasn’t possible to see if it was seated properly..

However the fitter had used some grease to try and retain it prior to fitting..

When I inspected the o ring it came apart indicating that maybe it had been pinched..

More worrying was damage to the mating face in the same area..was he poking the o ring back in ?

You can see compared to the new Polish version that the Polish version has a thicker more positively located o ring..

3 litres of fluid came out…I think it should be at least 5 litres ..

Frustratingly the Polish pan uses the OE pan drain plug which was thrown away when the US pan was fitted..

My £16 new plastic drain plug arrived today so I think we can start the reassembly can begin..

[jeebus87]

Looks like the pan seal was the culprit, if I'm looking at the photos correctly the majority of the oil was opposite the side panel, and the trans connector sleeve leaks down the side panel area as well. Make sure to use ISTA to get the oil leveling correct.

[B21]

I’m hoping after loading 4.5 litres up then I had to use Bimmergeeks Protool as my ISTA for reasons I’ve yet to work out wouldn’t talk to the DCT as well as a couple of other ECUs..

Followed the same procedure with a couple of commanded shifts into 1st and 2nd for good measure..another 2 litres went in…

So 3.5 litres came out and 6.5 litres of Fuchs finest went in..

Will revisit the crime scene this morning to see if it’s pissing out…again..here’s hoping

[jeebus87]

Originally Posted by B21

I’m hoping after loading 4.5 litres up then I had to use Bimmergeeks Protool as my ISTA for reasons I’ve yet to work out wouldn’t talk to the DCT as well as a couple of other ECUs..

Followed the same procedure with a couple of commanded shifts into 1st and 2nd for good measure..another 2 litres went in…

So 3.5 litres came out and 6.5 litres of Fuchs finest went in..

Will revisit the crime scene this morning to see if it’s pissing out…again..here’s hoping

3L difference is a heck of a lot of fluid to be missing from the trans. Just want to make sure you double and triple check the level as it's just as bad to be overfilled.

Nice setup you got there!

[B21]

Originally Posted by jeebus87

3L difference is a heck of a lot of fluid to be missing from the trans. Just want to make sure you double and triple check the level as it's just as bad to be overfilled.

Nice setup you got there!

The factory quote 7.1 litres for a full fill..with a deeper pan sump 6.5 litres sounds about right..

I’ll drive it now for a couple of days..then drop the underbody shield which I repaired while I was there and see what gives..

Wondered about using a smear of flexible joint sealant..

Pleased with my garage..may add a couple more sets of timber to the blocks to make it slightly more roomier under the car when working on it..