Hi all,

Kindly requesting advice and thoughts from you gurus and experts on the forums.

I've been facing this issue since I first got my used W219 CLS500 (UK Spec) about 8 months ago. My CLS is a 2007 model with currently 104k miles on the clock. This is my first ever V8 and wow what an experience! That is, except when the CLS starts misbehaving.

Initially I misdiagnosed my issue as a "power loss" problem. After owning it for some time now, I think I've isolated the problem to a torque converter lock up clutch issue. The car drives 100% normally except during certain conditions, as I shall try to explain below.

Symptoms:
When maintaining throttle input (be it WOT, or half-throttle, or at any throttle position) at a constant position for approximately more than 10 seconds, the lock up clutch engages, which causes the car to have limited torque/acceleration. The lock up clutch would stay engaged for some time approximately 1 minute, despite me giving variable throttle input. In such cases, the car would just immediately feel sluggish and would struggle to accelerate or even maintain the current vehicle speed.

Typical example of the case would be when accelerating from a stop light, and then when reaching say around 60mph, I maintain constant throttle input to stay at cruising speed of 60mph. After 10 seconds or so of maintaining constant throttle, RPM would slightly drop indicating lock up clutch has been engaged. After this happens, when trying to accelerate further, e.g. wanting to overtake a vehicle, and I depress the throttle, car would just feel really sluggish and wont accelerate. If I accelerate further, car would downshift to a lower gear, but still wont accelerate much. After a minute or so, suddenly the lock up clutch disengages, and I would feel a sudden surge in acceleration. And the whole thing just repeats over and over again.

Temporary mitigation:
Since I daily drive the CLS, I have learnt a few tricks so that I can avoid the "lock up" situation:
1. Constantly varying the throttle, avoid constant throttle input. I would literally tap on the throttle repeatedly with my right toe just so that there is variable input to the throttle.
2. When the car do gets into the "lock up" situation (sometimes its unavoidable) and I desperately need to accelarate, I would put the gear selector quickly into Neutral and then back to Drive (while still moving). This always help me get out of the "lock up" situation.

Diagnosis:
I had a generic OBDII code reader scan, and have pulled two codes:
P2783 - "Torque Converter Temperature Too High"
P0741 - "Torque Converter Clutch Solenoid Circuit Performance or Stuck Off"

My indy has no clue other than to replace the whole torque converter which I doubt is necessary at this point. My thoughts are perhaps its the clutch solenoid, or the clutch itself, but dont know if these components are servicable on its own. Perhaps I should try to do a fluid flush and a thorough clean of the conductor place first? I was told that the previous owner has done a rebuild at one point before my ownership of the car, at the same indy mechanic I mentioned earlier.

Your thoughts and advice?

Regards,
Mo420

 

Bump!

Thoughts anyone?

 

Bump

 

Fantastic description, I am experiencing the exact same issue. I will share what I know so far (no current fix). I have changed the fluid and filter using oem parts - no change what so ever. There was minor metal buildup on the trans pan magnet (not uncommon for my 124000 miles) that was cleaned out during change. We did drain and change the torque converter fluid also. I have dug up the attached paperwork that *may* indicate a torque converter replacement. I am about to install a new converter - but I am looking into a remanufactured unit for cost savings now that it is getting old and far from valuable. If you have come up with anything, I would love to know! I have been driving it in this condition for 4 months with no change other than check engine light (which goes away sometimes)

 

Hi Robert! Thanks for posting your experiences so far, glad to hear from you (although Im sorry to hear that you are facing same issue).

To answer your query, I have not done any work on the car so far other than a torque converter adaptation via STAR, done recently by my Indy mechanic. Sadly - no change at all. However, I noticed that my indy's STAR software is perhaps out of date as it does not allow "adaptation by temperature" feature in addition to the "adaptation by vehicle speed" that was being done to my car. Sadly that's the only indy countrywide with access to STAR that I know of. I have read a few MB articles suggesting the first step when facing such issue is to try and perform the adaptation, perhaps this is something you might want to consider trying out before replacing torque converter considering the costs involved (It didnt solve the issue on my car but Im not sure if it was done correctly).

Whilst on the subject, would you mind sharing a little background info - did the issue happened all of a sudden or if has been a gradual occurence which just got worse over the 4 months you have been facing it? For mine, unfortunately it was already like this when I bought the car (knowingly).

Thanks also for sharing the article! Really in depth description of the remedy for our exact issue and much much more helpful than the advice I've been getting from my mechanics. In short, main suspects are either torque converter replacement or a sealing ring leak.

Do let me know if you do proceed in replacing the torque converter, really interested to see how that goes (or if you somehow stumbled across a fix). I am also preparing to lean towards that route now, its just unbelievably expensive to get it replaced here in Brunei, even with a reman unit.

Best wishes,
Mo420

 

Hi Mo420!

I am experiencing the same issue that you described on my 2007 ML 320 CDI! Did you manage to solve the issue? A reply would be appreciated!

Regards,

 

Hi! Unfortunately I have been quite overwhelmed with work and family matters and havent gotten a chance to get my CLS fixed. But Im slowly doing research and saving up for a new torque converter as I believe therein lies the issue. Let me know how you get on with yours!

Regards,
Mo420

 

Hi! The problem was solved by changing the torque converter... I've managed to source factory reconditioned Sachs/ZF Torque convertor for 400Eur with core exchange of the old part. If you plan on doing the repair on your car, I suggest to completely disassemble and clean the valve body and replace the valve sealing O-rings.
In my case there was substantial amount of aluminum shaving when I have separated the plates, also on the top of the valve body and in the pan there were too. Funny thing that I noticed is when I was removing the valve body from the trans, it was missing one bolt from 6, on the side of the hole for the filter. Maybe that was the reason for the my failure or just someone forgot to put all of them back...

Hope you'll successfully fix your car.

Regards,

 

My symptoms were identical, but I would not describe as a lock-up clutch engaging, more like power loss and acceleration limit as an intervention of the TCM. Also I had no lock-up clutch at all, as I was in the Neutral after I release the accelerator, and when accelerating the rpm were jumping as a clutch slipping in manual transmission car.

 

Hi! Thanks for the update! Good to hear you have now fixed your ML! Cant wait to get mine fixed too now.

Any tips/recommendations on sourcing the factory reconditioned torque converter? I'm having trouble finding it locally and considering shipping one from UK. I understand there are different torque converters (e.g. 2 disc and 3 disc - in my case the M273 is mated to a 3 disc core).

Also, from my research, it is recommended to sand down the pinion shaft prior (or something similar) to installation, was this done during your installation?

Lastly, was wondering did you find there's any need to perform STAR reprogramming after the install?

Thanks again for the update and enjoy the drive!

Regards
Mo420

 

I’m having the same issue and changed the torque converter with an oem rebuilt one but still am having the same issue.

 

Sorry to hear that you got the bug too. I didnt get to resolve mine, ended up just selling the car.

However I remember that the closest I got to resolving the issue was this:
1. Check that the torque converter calibration (temperature dependant) was done successfully. I remembered it had to be done during cold starts when the transmission oil temperature was below 40 degrees celcius.
2. If you have the error code for "torque converter lock up clutch performance" I also suggest to look at the associated solenoid valve which controls the lockup function - Y3/8y8.

 

Thanks for replying, I did change the Y3/8Y8 solenoid and no change unfortunately. Clueless on what to do now the conductor plate was done 2 years ago too with the updated VGS3.

 

Just a thought, did you get the calibration/TC learning process done succesfully?

 

I’m a little confused on that procedure not so much information online on that and I highly doubt my mechanic did. Although I did just do the transmission reset which is the one when you step down on the throttle ignition on and let go then start up in 2 mins. Could you elaborate on the TC calibration learning process? Btw this whole issue is on a 07 GL450. Thanks a lot

 

I drained oil and found out it was less that 5 liters and then replaced with 6 liters but its slapping all the 7 gears so i do not know what could be the problem, some are saying it might be low oil and probably air in the gearbox
its Merc w204 7 speed
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I drained oil and found out it was less that 5 liters and then replaced with 6 liters but its slapping all the 7 gears so i do not know what could be the problem, some are saying it might be low oil and probably air in the gearbox
its Merc w204 7 speed

 

New conductor keeps slapping gears: run adaptations with Xentry to train normal shifts...
but it shouldn't be far away from adapted either