super7pilot

Had my '14' GLK250 in for a service 'B' today. One of the issues I raised was the thud/clunk a few seconds after coming to a stop. The service writer and I went for a test drive and miracle of miracles. The problem actually presented itself instead of hiding for the test drive. They put in the software update that was mentioned on another thread (three things you don't like about your GLK) about this and other issues. The tech said it still had the issue when he drove it after the update. I didn't notice it on the way home.

Now, The cause of the issue (as explained to me by the tech) is the fact that the MB auto trans has a locking torque converter for better efficiency. Upon stopping for more than a set amount of time at a light. The computer will back off the torque converter completely (almost like a neutral position) while in gear to ease the load on the engine. When the load is released the driveline suddenly 'relaxes'

It's a similar (but much much less) effect as having a manual trans and dragging the clutch a bit and pushing the gear lever into neutral thus causing the drive shaft to ring from the backlash on the ring & pinion gears when torque is suddenly released on the driveline.

formerjeepguy

Thanks for the explanation.

My 2014 glk250 did this a few times, but the 2015 glk350 has not yet done it.

bop11

Do you hear this thud when you take your foot off the gas and the wheels are driving the engine (no brake) such as coating down a hill? Do you get it when you go from coasting to power on? Even if the explanation is correct, there must be excess play in a CV or other joint to make a thud sound that you could hear inside.
The 2015 350 GLK probably has the engine turn off system so you would not need to release the converter with the engine stopped.

super7pilot

Just when I come to a stop and I'm depressing the brake pedal. The thud is barely audible. It's more like a single bass note and you feel it more than hear it.

I'm not worried about it in the least as it does not sound like a mechanical issue like when one has to much ring & pinion back lash.

bop11

Might want to check your suspension bushings. That type of sound was typical on Range rovers at about 50 k miles from defective front bushings. Also check the upper Struts.

super7pilot

bop11,
MB knows what causes the sound. Please see the second paragraph in my first post. It's a transmission programing issue. There is a software update for this issue. LI27.19-P-56898

super7pilot

An update. Just took the GLK out for a spin through downtown Walla Walla. It would always make that noise when pulling up to stop at a light. It has done this since buying our GLK in May 2014. Today I never heard that noise under the same scenario. The one time it did make that noise was when I was just starting to move after being stopped and just a second later had to stop again after very momentarily getting on the throttle.

So it seems that the transmission software update was (mostly) successful.

tigerdog

We just purchased a 2015 GLK250 Bluetec and I immediately noticed the same thing. About 3 seconds after coming to a stop, it feels like the car has just been tapped on the bumper from behind. Good to know there's a service bulletin on the subject; we'll have it looked into at the next visit to the dealer.

LesF

The clunk. I started getting it a while back. Going to let the dealer fix it next time in.

super7pilot

Mine came back not long after I posted that it seemed to be fixed. I guess it's something I need to get used to. As it's caused by the torque converter going into a neutral condition I'm not going to worry about it.

But folks might still want to have that software update done as it will at least have your issue logged into MB's system before the warranty expires. If it does become an issue later. It gives you the opportunity to have it looked at under the warranty due to it being logged as an existing issue.

andreigbs

Greetings all, I too have the soft thud several seconds upon coming to a stop. Just picked up our CPO 2014 GLK250 last week with 48K on the clock.

First service scheduled in a few months, I will inform my service advisor about an available update. Thank you kindly, super7pilot, for relating your experience. I'm mostly relieved it's probably nothing serious, although I would like to not feel/hear it from a $30K luxury CUV.

tigerdog

I reported this issue earlier. Our GLK250 now has 25000 miles on the clock and was due for maintenance, so I reported the "thud" to the service advisor when I dropped off the trucklet. To quote the service notes verbatim:So it seems this is a known issue with a service note (LI27.19-P-056898 seems like a service note number.) Interestingly, there is absolutely no mention of a software update on the service invoice, just the mechanical changes noted. I can confirm, whatever was done took care of the problem.

I hope this helps others with the same issue. Given the amount of labor in the description, it's definitely something you'll want to have done while still under warranty!

ecohen2

I have the exact same issue and suspect that it is the transmission doing something and not the engine. My local dealer is hopeless so I am curious what the fix is or if it is just the way it is. I also have a C63 that in sport mode going down to 1st makes a much harsher clunk that is "normal" according to the dealer..

Ed

PBC

I also got same noise problem about 3 sec after full stopping. This noise "thud " does not come on every stop, but thud noise is frequently heard when my cold vehicle stops for the first few miles.

Today the MB advisor confirmed the thud noise came from the propeller shaft and the transmission.

MB mechanic lubricated the propeller shaft , re-program the transmission module as per TIPS ZM941010. Propeller shaft from transfer case to front axle was removed, installed to establish the finding. Checked the data bus and control unit...

I hope MB mechanic fixes the thud noise from the transmission system, and I will confirm the MB solution after few more days of driving.

Initially two other MB advisors suggested that thud noise came from torque converter to improve gas mileage by about 5%. This special gas saving feature comes with the torque converter noise problem, and this torque converter shut down noise cannot be eliminated.

Hope that is not truth, and it seems no logic to it.

I do not know what is the real cause of transmission noise.

I just want to log in this transmission noise issue in case of future warranty issues, and hopefully I am still eligible for free warranty fixes.

I will advise other MB owners to ask MB to check out any noticeable noise when your GLK 250 vehicle is still under free warranty fixes.

MB recently replaced two GLK 250 front shocks after I complaint about the strange noise from the front end during the first few miles of driving. Maybe the 2014 shocks had tight tolerance when they were cold and caused friction noise.

After the front shocks were replaced under MB free warranty , that noise was totally gone.

It is a drag to report these noises, but it will eliminate these expensive repair cost and provide you peace of mind in the long run. Report these noise problems especially you still have factory warranty.

mojomatsu

After downloading data from the transmission and sending it to MB Canada, the dealership and MB Canada finally have resolved this issue. They replaced the transmission valve body under warranty.

Fagunza

Mine has been doing this as well, especially after a quick stop. I thought it was the DEF fluid sloshing. I agree with super7pilot's assessment because I have noticed that about 2 seconds after stopping I can pull on the left shift paddle and the transmission feels like it downshifts. I wonder if anyone else can duplicate that.

Anyway, I'll see if the dealer will install the software update or even knows about it.

Thanks to everyone who has commented on this issue.

andreigbs

Mine is scheduled for this as well. Will update once diagnosed.

Fagunza

Finally had the dealer perform the LI 27.79-P-0556898 on my 2015 last week. Problem solved and covered by the warranty. They also checked on a software update but found none that applied. I believe my service advisor said the software update only applied to 2012 models and earlier. My wife's 2014 model has never had the problem.

SirL

Took the 2014 GLK250 in for the thud about a week ago. I gave them LI 27.79-P-0556898 and said this should fix it. They performed the service as well as a transmission programming that was not on my service receipt. Thud is gone and gears are shifting smoother than before I went in.

Alex Bel

Lucky you. They did software update on mine, but thud still here. I get used to it and not worry much.

SirL

Now that a couple more weeks have passed I can say that the thud has been back - but only twice and not as severely as before. Things have definitely improved, but I'm wondering if this will be a service needed every so often in the future...

vaxhu

mer250glk

I also have the same issue. Mine is 2015GLK250. I have over 70k on my transmission. I called the dealer here at Ontario CA to check it out and they said they will charge me 175 dollars for diagnostic. What I don't understand is why they always charge for diagnostic when I already told them what the problem is. I am not going to this MB dealer/service place anymore.

jekebit

I had the same issue with B250 4matic.. It would become worse at times almost feeling like you got hit at the back by another car. Today they upgraded the SW and on the way back I still felt a bit of thud but much more subtle. It is not completely gone. I will see if it comes back. Based on your explanation . This does not seem to be harmful to the transmission. Is that correct ?

vaxhu

This function explain by a mercedes engineer is called “KID” that mean Kraftlos in D, its just a particularity of this automatic shift and its functionality is to reduce power and secure the car when is stopped and ready to start. Till now i had no problems only the terrible thud noise sometimes but now i’m used on it. Most of the mercedes engineers told there is no problem on doing that noise. So don’t worry keep go and enjoy you mercedes