DCT issues after driving hard

[tdott]

Originally Posted by azndrunk74

I went to check the fluid level of my transmission and it was completely full. As soon as I removed the fill plug tons of fluid came out.

Unfortunately, the transmission has been freaking out even with normal driving. While I was stopped the transmission malfunction light popped on and I had to restart the car in order to get the car into gear and drive.

Should I even bother doing a fluid flush and filter replacement or just just drop in a whole new (used) transmission? Could my fluid be so old that it's causing the transmission to overheat and do weird things? Or is the entire thing just done/dead? The weird thing is this started happening immediately after the test pipe install. I'm sure it's more coincidence than correlation.

Did you follow the correct procedure when checking the fluid? Car has to be running and upto temp. Check the other thread for exact steps, pulling the drain plug with it off will not get you an accurate reading.

[redpriest]

A phone call to BMW NA at my dealership's recommendation, and some discussion on the phone is what I needed to do. I was asked if I had tracked the car (I hadn't). I was just barely out of warranty, but they hooked me up even though I wasn't the original owner.

The dealership also took the time to replace all the gaskets preemptively. I didn't mind since it was not at my expense. And honestly, 2k or so including the removal of the transmission isnt that bad when you consider what it costs to replace the brakes. If they don't have to remove the transmission to replace the side and top gaskets it's far cheaper.

[SJL Custom]

Heres what I would recommend at this point. Drain all the fluid that is currently in the trans. Measure the amount that comes out. Depending on the year of the trans, there is an additional steel drain plug located inside the drain plug in the plastic pan. Drain this as well. Since you already have new filters etc, I would pull the plastic drain pan and replace all the filters as well. Be sure to catch all the remaining fluid from the pan when you pull it and record how much total fluid you have drained. Pull the cooler lines from the side of the trans and catch all this fluid as well and add it to the total drained. What is the total amount of fluid that you have after this?

[SJL Custom]

Now after you have replaced the filters etc and have everything back together and are ready to fill it up, this is the easiest way to do it. The fluid capacity of the trans with cooler included is 9 liters. Take that nine liters and put all of it in the trans. Don't worry about overfilling it by a liter or whatever, it wont affect anything. The GTS actually uses the same exact trans but is overfilled by I believe 1.5 liters, so if theres ten liters in there, there wont be an issue. Now drive the car and see what happens. Make sure first to erase all previous codes and if its possible, do a oil condition reset, clutch adaptation, gearbox relearn, torque characteristic reset and teach in valve characteristics with the wheels off the ground and the car started in neutral.

If still after all of this you still have the same issues, something further is wrong and will require the trans to be removed.

Side note. While you have the trans pan removed, inspect the magnet attached to the plastic pan. Make sure there are no metal filings found. A grey sludgy material is normal. You could also cut open the bottom pickup filter as well to inspect for non metallic fillings and debris. All this will lead to a proper diagnosis of the issues youre having

[Leonardo629]

I'm gonna bet my money on a faulty mechatronic unit, which I also bet has been killed by the heat if your DCT unit has been leaking for a while.

[azndrunk74]

Originally Posted by tdott

Did you follow the correct procedure when checking the fluid? Car has to be running and upto temp. Check the other thread for exact steps, pulling the drain plug with it off will not get you an accurate reading.

yes, the car was up to temp and running when i checked the fluid level.

Originally Posted by SJL Custom

Heres what I would recommend at this point. Drain all the fluid that is currently in the trans. Measure the amount that comes out. Depending on the year of the trans, there is an additional steel drain plug located inside the drain plug in the plastic pan. Drain this as well. Since you already have new filters etc, I would pull the plastic drain pan and replace all the filters as well. Be sure to catch all the remaining fluid from the pan when you pull it and record how much total fluid you have drained. Pull the cooler lines from the side of the trans and catch all this fluid as well and add it to the total drained. What is the total amount of fluid that you have after this?

Originally Posted by SJL Custom

Now after you have replaced the filters etc and have everything back together and are ready to fill it up, this is the easiest way to do it. The fluid capacity of the trans with cooler included is 9 liters. Take that nine liters and put all of it in the trans. Don't worry about overfilling it by a liter or whatever, it wont affect anything. The GTS actually uses the same exact trans but is overfilled by I believe 1.5 liters, so if theres ten liters in there, there wont be an issue. Now drive the car and see what happens. Make sure first to erase all previous codes and if its possible, do a oil condition reset, clutch adaptation, gearbox relearn, torque characteristic reset and teach in valve characteristics with the wheels off the ground and the car started in neutral.

If still after all of this you still have the same issues, something further is wrong and will require the trans to be removed.

Side note. While you have the trans pan removed, inspect the magnet attached to the plastic pan. Make sure there are no metal filings found. A grey sludgy material is normal. You could also cut open the bottom pickup filter as well to inspect for non metallic fillings and debris. All this will lead to a proper diagnosis of the issues youre having

thanks for the suggestions, i'll give it a shot. from reading the DIY on this forum, i thought the max that we could drain was 4-5L? is it really possible to drain the entire thing?

[AWF87M2]

sorry to hear. 6mt is the way to go if you plan on keeping it long after the warranty.

[SJL Custom]

If you remove the pan and the hidden drain plug, and drain the cooler as well, the majority of everything should drain out. Just make sure to measure what was removed.

[SenorFunkyPants]

Originally Posted by tw4life

sorry to hear. 6mt is the way to go if you plan on keeping it long after the warranty.

Yet the DCT is proving to be *almost* bullet proof.
Against dozens of MTs being swapped out for failed syncomesh, along with broken flywheel tabs and worn clutches - the number of DCTs that have seen (non dealer screw up caused) failures is extremely small.

[///M Power-Belgium]

Originally Posted by SenorFunkyPants

Yet the DCT is proving to be *almost* bullet proof.
Against dozens of MTs being swapped out for failed syncomesh, along with broken flywheel tabs and worn clutches - the number of DCTs that have seen (non dealer screw up caused) failures is extremely small.

Spot on !

[Helmsman]

Originally Posted by ///M Power-Belgium

Spot on !

Tend to agree here. From 2008 onwards track record seem to show that under normal use the DCT seem close to impossible to wear out or even abuse to break. The one cause remaining is when the minimal maintenance required isn't done properly. No offense OP, the leak can be sneaky.

[azndrunk74]

Originally Posted by SJL Custom

If you remove the pan and the hidden drain plug, and drain the cooler as well, the majority of everything should drain out. Just make sure to measure what was removed.

ok great. thank you!

i'll keep everyone updated on how the fluid + filter change goes and how DCT relearn/adaptation goes. fingers crossed.

[V8FunNaturally]

Originally Posted by SenorFunkyPants

Yet the DCT is proving to be *almost* bullet proof.
Against dozens of MTs being swapped out for failed syncomesh, along with broken flywheel tabs and worn clutches - the number of DCTs that have seen (non dealer screw up caused) failures is extremely small.

You are hilarious. DCT record of troubleshooting, weird behavior, and now leaks is abysmal and it's only going to get worse as they start failing like this one. MT are bulletproof by far and large. The few overpublicized ones where the drivers or its previous driver had ruined the synchro mesh through mis-use or abuse are few. With more power comes more responsability. It takes more responsbility to own a Manual transmission than a dct, yes you can screw the synchros if you don't know what you're doing, yes you can drop the clutch to kill it, with more control comes more responsabilities. If someone intentionally wants to destroy and ruin a manual, you CAN ! you are in total control of it. You can also push it as much as you want as long as you you're not misusing it. But you couldn't abuse a dct that easily because the end computer commands overrides the driver. YET what we see is they are less reliable and more problems are surfacing , leaking and ending their life earlier.

Manuals are not an idiot proof toy by virtue of their direct command from man to machine unlike dct and as most BMW manuals it's not the friendliest manual to learn on (especially for americans used to automatic muscle cars) Well used it is bulletproof. Synchro problems ARE all user misuse and abuse. Not factory or design issues like DCT.

And ask any dealership that sees a lot of M3, they'll tell you dct complaints and mechanical problems are becoming more prevalent. While manual issues are always related to misuse of the freedom it gives you.

And yes the dct was supposed to be maintenance free. That pretense is gone now people, now it's already about when will it start to slip and end life.

BMW mdct 2008 official publication quote :

"Dry sump lubrication, in turn, guarantees a high standard of reliability and maintenance-free function throughout the entire running life of the car."

maintenance free throughout the entire life of the car. Getrag was much too optimistic

[Beemdog]

BMW's decision to claim that the DCT would be maintenance-free was ill-advised. It seems unwise to never change the lubricating fluids in any gear-based transmission for a variety of reasons.

On another topic, the folks who are making it a personal vendetta on this forum to lambaste particular options they did not purchase (convertible tops, moonroofs, DCTs, etc.) look pretty foolish, IMO. If I had a bad experience with something on my car and could pass that on to others here that is one thing. To be harping on about 'this and that sux' even though I've never owned one or had this happen, and everything I think I know I read on a forum, well, we could do better. Every forum has a level of maturity and this one could use an upgrade.

[wyatth]

^ Agreed. And even as a 6MT owner, I am even finding that degree of bashing in this thread inappropriate.

[bimmerfrk]

Originally Posted by wyatth

^ Agreed. And even as a 6MT owner, I am even finding that degree of bashing in this thread inappropriate.

^ super agreed

So many little 6m vs DTC bitches in the thread. Move on and leave your daddy's m3 alone he bought a 6m or DCT for a reason, stop crying yourselves to sleep.


OP I feel your pain man. Like others have said give it a rinse with some fresh fluids and see how it goes.

[V8FunNaturally]

Originally Posted by SJL Custom

Heres a fact. I have a customer running his 335is dct at over 500wtq and 550whp on SSP clutches for over 50000km with zero issues to date. He BEATS on the car daily and since installation, I have never received a call related to any problems. After two years, I had to call him for an update and to ask if everything was alright. He told me "Yes everything is fantastic. I love this trans now. It pulls and shifts so well. People cant believe how fast the car is. I even pull GTRs!"

The rating by Getrag is based on the clutch capacity, not the gearbox. The same gearbox is used for all BMW DCTs and is rated at as much as 700nm (518ft/lbs) in the M5 and M6. I have worked on and upgraded numerous BMW DCT transmissions since 2012 and have yet to see a gear box failure. I am also one of the fortunate few to have ever disassembled a complete BMW DCT to study it, look for and address the weak areas. Im not saying it wont at some point, but as of right now, no one has broken a gear.

So you tinkered with dct transmission in your spare time and have complete arbitrary ideas. No relevance whatsoever. I'm talking about hard design Engineers Specifications no enlightened individuals frivolous assumptions.

[V8FunNaturally]

Originally Posted by Beemdog

BMW's decision to claim that the DCT would be maintenance-free was ill-advised. It seems unwise to never change the lubricating fluids in any gear-based transmission for a variety of reasons.

On another topic, the folks who are making it a personal vendetta on this forum to lambaste particular options they did not purchase (convertible tops, moonroofs, DCTs, etc.) look pretty foolish, IMO. If I had a bad experience with something on my car and could pass that on to others here that is one thing. To be harping on about 'this and that sux' even though I've never owned one or had this happen, and everything I think I know I read on a forum, well, we could do better. Every forum has a level of maturity and this one could use an upgrade.

Unless you were active in this forum in 2008 when dct was released (i was albeit on a previous account) you have no idea of the context. In those days, with bmw marketing elliptically backing dct, skeptics said wait and see a few years for reliability. Here we are this is now. I always include informative references in my post. 6MT / DCT is always controversial. Your self righteous post brings nothing but vacuum and posing puritanism.

[SJL Custom]

Originally Posted by V8FunNaturally

So you tinkered with dct transmission in your spare time and have complete arbitrary ideas. No relevance whatsoever. I'm talking about hard design Engineers Specifications no enlightened individuals frivolous assumptions.

Tinkered in my spare time? Dude, I build, design and re-engineer transmissions. Its my profession. Youre the one talking about gear strength etc. When your manual breaks, don't give me a call to fix it properly.

[BzsBimmer]

Originally Posted by V8FunNaturally

So you tinkered with dct transmission in your spare time and have complete arbitrary ideas. No relevance whatsoever. I'm talking about hard design Engineers Specifications no enlightened individuals frivolous assumptions.

Originally Posted by SJL Custom

Tinkered in my spare time? Dude, I build, design and re-engineer transmissions. Its my profession. Youre the one talking about gear strength etc. When your manual breaks, don't give me a call to fix it properly.

[Beemdog]

Originally Posted by BzsBimmer

Shhhhh, don't feed the troll (or whatever it's called when half of what they write is so abrasive it makes 30-grit seem like silk). I get the feeling some don't even know they're being abrasive-- it just comes 'Naturally'.

[V8FunNaturally]

Originally Posted by SJL Custom

Tinkered in my spare time? Dude, I build, design and re-engineer transmissions. Its my profession. Youre the one talking about gear strength etc. When your manual breaks, don't give me a call to fix it properly.

"re-engineering" is what true engineers call tinkering. In all technological fields there are tinkerers/repairmen (including people who do this for a living) that disassemble and reassemble things. At best they understand how it is "supposed" to works sometimes with oem manuals but this does not even get close to comprehending a design degrees of freedom, margins, optimizations and mechanical stress design. That's the professional playing field of the design engineer that chose and created the design. Repairmen are of course valuable but when i quote the engineers for the module, anything a transmission rebuilt/repairman has to say on top is only background noise.

That said, you are right the wet clutch packs is the weak link not the gearing. A stock dct can overheat in a hot day if pushed continuously until the computer puts the car in limp mode.