Huz-Z

Hi All,

This is my first post and I'm profoundly disappointed with the brand new 2014 C300 4matic my wife and I recently purchased. Its quite nice EXCEPT for this amazing problem. This is our first Merc and I am decidely unimpressed.

It shifts with a CLUNK. Seriously. At low speed (20 to 30 kph) and low rpm, if you give it a squeeze on the gas, particularly if the car is on a slight uphill grade, the transmission will clunk and that can be felt in the car. The car only has 2200 kilometers (1400 miles) on it.

We have had the car to the dealer (had to wait a month for a service appointment) and they returned it "repaired" but the problem was still there when I drove it the next day, so I guess they did not fix it.

Is this a common problem? I am considering bringing the car back to the dealer and walking away from this thing. I should add that other than this issue, I really like the car. Its got plenty of guts, good looks and nice toys. Just need this problem to go away.

EuroJDMBenzo

is it a clunk noise? or a clunk jolt? could be the car just shifting gears lol

Huz-Z

Its a noise and a jolt and you can feel it through the car. If this normal, this is the worst shifting and roughtest transmission I have ever driven

djejglk

Does it literally shake your body, or is it just a lot louder than one would think? Or both?

I have a 2013 c250, and the transmission/shifting is very smooth, but it's also not a 4matic. Either way, it still doesn't sound right.

I suggest being able to repeat the problem steadily somewhere around the dealership, then "test drive" another c300 on the lot and drive to the area where you know where your car was having the issue.

If it's repeatable, 99% chance it's just the way it is. BUT, if the dealership "fix" lasted any amount of time and the problem came back...that's a problem.

Huz-Z

Thanks for the comments.

When this happens, you can hear it, but you can also feel it. It really is a clunk in the transmission which I think is happening on downshifts. Its not the engine changing rpm on downsshift and its definitely not right. I can't imagine Mercedes going to market with a car that does this, so it must be some kind of fault.

In fact, its so rough that I would expect that if this continues, some part of the drivetrain is going to break or snap, it sounds that bad.

vic viper

I am guessing its equipped with the 7G-tronic 722.9 transmission, if so it could be a single magnetic valve that needs replacement, if that doesnt help you may need to replace the entire valve unit including the transmission control unit (situated inside the valve unit)


But first of all I would try to upgrade the transmission software.

w204_Generic

Sounds like some other people are having the same problem. However, I don't know if this means that this is normal though.


https://mbworld.org/forums/c-class-w...g-problem.html

adanmtxt1

The transmission should shift cleanly and without harshness. It's entirely possible the software responsible for transmission control needs a reflash, but it's not 'right'. A family friend bought our old 2008 335i, and a couple years ago the tranny started shifting harshly, with a hard 'clunk' and recoil. Turns out the auto 6speed with that car is known to have problems and can be an expensive repair. The good news is the software was reflashed and the harshness went away.

Take it to MB and pursue it until it's corrected. It's a Mercedes-Benz, not a thrashed Freightliner.

acr2001

I think a better description is necessary. You say that you can feel it shift, but this is perfectly normal. Especially when it's being / recently been driven in a sporty manner. It depends on how harsh it is. If its very harsh then yes, certainly a problem. You can certainly feel the car shift. I've never been in a car where it can't be felt to some degree - and I think most drivers like that. It should be smooth though, unless you've been driving like a maniac in which case, it will deliberately shift quickly, which is a bit more harsh, but expected and enjoyed by those who are driving the car very hard. If you're driving it gently, then, once again, it should be pretty smooth.

If it's shifting so hard that it's jolting / moving you in the seat, then hell no, not normal.

MBSebas87

+1.....dealership should fix the problem even if it means replacing the tranny imo

tonyteetime

Huz,

I have a 2013 c300 and the shifting is smooth even on downshift on both eco and sport mode. The clunk noise that you've describe is not normal. Take it to a different dealer to diagnose.

Huz-Z

I'm 51 and I've been driving automatics since I was 17 so I can assure you that this is NOT a normal thing. when you depress the accelarator at around 1,000 rpm and low speed, the car will exhibit a hard clunk and you can almost feel and hear the universal joints rattling in the drivetrain. I just came back from the dealer and the service manager thinks its coming from the rear differential. I've been able to replicate the problem for him and he knows what I am concerned with. And he and the salesman we bought the car from both agree that it does not sound like a normal thing. I'm cautiously optimistic that this will be resolved and I'll let you know of developments.

In the meantime, all advice is welcome.

xaran

Continue to follow up with the dealer for repair to your satisfaction! Id drive another new C 300 and compare your car to that and until it is the same dont accept it!

In my experience with my C (even though its not a 4matic and you have a lot more to deal with with all wheel drive, transfer case ,axles etc) the transmission in the C is the "softest", most lazy automatic Ive driven or owned in years. So a hard shift or clunk is not normal.

Huz-Z

Thanks.

I've been speaking to the service manager and he says he is confident that this can be fixed with a software update; that may happen on Friday or early next week. I'll be sure to let folks know if this clears the issue (and I sincerely hope it does).

tonyteetime

I hope the issue can be cleared with a simple software update. Good luck!

mikc300

Quite the opposite to my 2014 C300, only had it a few days so far, but shifts are hard to notice, in and out of reverse or drive, has no clunk or any sort of sound. Best of luck.

w204_Generic

Isn't that a good thing?

Samaral

Keep "bugging" them. My car shifts perfect fine. No issues whatsoever.

acr2001

Ok, absolutely then. Just got a little concerned based on the initial description - sometimes we get crazies! Sounds like it's a pretty obvious problem then and certainly not normal. Keep on them until they fix it right.

Huz-Z

Thanks! I appreciate all the help you and others here have offered. This is a nice community! I'll be sure to let you know how things go with the software update.

Cheers!

bop11

Simple, just go to the dealer and drive another one. They should have one on the lot. If it does not do the same thing, then you have a problem. We all have different tolerances to things, but two brand new cars with the exact same problem is not very likely. If there is a difference get the dealer to fix yours until it is like the other one.

Huz-Z

Thanks for the suggestion!

Ideally, yes. But the service manager did tell me that there is a service bulletin out for rough shifting on the C300 4matic. So on that basis, its possible that other new cars in the dealer's inventory may also have the same problem. So - two wrongs don't make a right!

(My first MBWorld joke! )

But to your point, the salesman was going to take another car out for a spin yesterday to see if it had the same problem and if it did, then they were thinking that maybe its a normal thing. But the only call I got from them was to schedule an appointment for the reprogramming, so I'm concluding that the car the salesman drove did not clunk when shifting at low speeds like mine does, and they view this to be a legitamate problem.

Cheers!

xaran

Let us know how it works out.

My 2012 C 250 was one of the models that fell into a TSB to reprogram the ECM. It was to address the transmission downshifting and engine response (lag?) the dealer did it during my "B" service last month and it may have helped a little. But overall our C class (excluding the C63) have pretty unresponsive, lazy transmissions.

Huz-Z

We had the programming done and now the car is if anything, significantly worse.

Its my wife's car and she has asked that the car be replaced by the dealer; at this point we have no faith that Mercedes can repair the car. Personally, I'd perfer to get my money back so we can walk away from Mercedes altogether.

Sportstick

The change, even if worse, would suggest this is the core issue. However, instead of talking to the dealer, directly call MBUSA and find out when/where one of their local technical specialists is visiting that or another nearby dealer. The service manager at your dealer may also know. You need a meeting with that person ASAP. The Uniform Commercial Code and local lemon laws require that you give them a chance to repair the problem before they have an obligation to void the sale, unless they are willing to goodwill the exchange (which would keep you with MB anyway). Try not to let your frustration win yet. This may be a simple fix, if done properly.