So I have a 2013 (new to me) C250 with approximately 48K miles. After driving on the highway for about 30 minutes and then getting into slower, stop and go traffic, I notice a popping or knocking noise underneath the car. I've taken it to the dealership and they replaced the sway bars/links....course I don't know what that is, but they're replaced. This did not help the noise. Anyone have that sort of sound? It happens as the wheels turn. It seems to come from the driver's side. Course I had the dealership technician ride with me and NO FREAKING NOISE. They're keeping it and will try to get the noise to occur so they can pin point it. Maybe it's just a characteristic type noise?

 

Not to give you a hard time at all, but did you know you posted this in the W205 section (2015 and up)?

 

Thanks for the heads up.

 

I have the same problem VinnyGirl is describing....however, it is a 2016 C300.
And of course, the car made no noise when the technician rode along.
I hear a clunk when turning into a driveway or pulling out backwards and turning.
If the noise happens, it happens in pairs....ie., if the clunk sound was heard during a right turn, then another clunk will happen on the next left turn. Otherwise, the suspension sounds ok on speedbumps, highway and all other situations.

I would appreciate any kind of help.
I can't reproduce the problem on demand, so the techs think I'm a hypocondriac.
I love my car but I hate what it does (clunk.)
Can anyone tell me how I can get service to take me seriously and actually fix my car?

 

Unfortunately if you can't duplicate it for the service department, it won't be fixed because we can't find it either.

Popping when turning is normally ball joint related, but it tends to always happen. Your mention of happening once to the right and left makes me think possibly the rack mounts aren't fully tight and it's shifting, then going back on the opposite turn.

I would suggest, narrow down exactly when it happens. If you can get it to reproduce, tell the service writer exactly how. Eg: It happens when I back up, turn full right, then go forward and full left. If you can do that and make it make a noise, demonstrate it to a service manager or shop foreman or someone, or see if a tech is available for you to show.

Generally speaking, if we can make it happen we can find it, but when a car comes in with a "makes a noise sometimes" complaint, it's impossible to know if we are even driving the car in the same manner as the owner is to make the noise appear.

 

Thanks for your reply, ItalianJoe1.
I appreciate your time and knowledge.

I will ask service to check the rack mounts....but my dealership is an AutoNation...and they seem to blow off requests such as these...they'll take my car in for a day, fix nothing and return it to me covered in silicone and cheap air freshener.

Would you be interested in looking at it?

 

I had that same sort of sound on both my old 09 GTI and 13 GTI. The sound was coming from loose subframe bolts. It was annoying as hell in stop and go traffic. Had them tightened and helped a little. Was only really evident in warm weather weirdly.

 

I have the same noise with my car. Each time I turn left on a driveway it makes a clunk noise.
I went to my dealer 3 times and the could not fix it.
At the end the guys gave a call to the headquarter in Stuttgart and the answer is that this sort of noise is known with the company. They are working for a solution.
The sound is meant to come from the steering system.
Once knowing that I took a rental car and did some test drives. I could reproduce the sound with the rental car as well BUT!!! it was on the right turn.
So unfortunately not to good news (I guess).
As soon as my problem is solved, I'll let you guys (and ladies) know.

 

We are having a similar problem. Mostly hearing the knocking when backing out of the driveway or making a turn. Although we're not having the corrective issue you have - ours is random and doesn't mean that when it knocks on a right turn it then knocks on a left turn.

What I have noticed is this - it moves from left to right to center. IOW - sometimes it comes from the left, sometimes the noise is in the center, and sometimes it's on the right side. I also hear it (rarely) when driving on a straightaway. So it's not always when turning.

The other thing I have noticed is when there is more weight in the back of the car, the noise gets louder. So we had a friend (250-300#) sitting in back on the driver's side. We had just pulled into a parking space and it knocked LOUD (scared me, actually, so that I jumped - I actually thought our friend was messing with us, but he said he wasn't and said he heard it coming from over his left shoulder). Today my son and I went to the grocery store - the knocks were faint but audible on the way to the store, and louder when we got home with a trunk full of groceries.

Another thing I noticed - when my son was driving and making hard turns (because he wanted to feel the power of the car so he was really accelerating out of a turn), we didn't hear any knocking. When we asked him to ease up when he makes a turn, bingo - heard the knocking.

The last thing I'll say about the noise is we hear it nearly every trip we make. Sometimes it's right off the bat pulling out of the garage, sometimes it isn't until later into a drive - 20min, and sometimes it takes 3-5min before we hear it. But that being said, I have run to WaWa 7min away, hear it twice on the way and don't hear it at all on the way home.

Our car goes in on Wednesday. To get around the problem of Murphy's Law - where you can't replicate the problem with the service tech - I have been audio-taping while we're driving. I get the best audio when I'm sitting in the back with someone else driving because I'm closer to the problem.