Clunking Noise
Senior Member
Joined: Nov 2016
Posts: 265
Likes: 54
From: Los Angeles baby!!
2020 C300 Sedan
I am not sure this is a good idea to do because we still don’t know if this noise can cause brakes to fail completely. I did some hard braking that did not trigger the abs and the noise was there. This is not abs. I have had to brake where abs gets activated in the past on my 2020 c300 and it never resulted in this noise. The feeling I get when Abs is activated is that it grabs the brakes, this is not that. This is a thump/clunk when braking. As I said I can hear it and feel it as I brake.
This noise comes on in my car if I brake by pushing the pedal with more force/weight on the pedal but not enough to invoke abs. When Abs gets activated it does not keep thumping as I brake which is what this is doing.
I keep telling the dealer that from the moment I took this car home I felt the brake pedal has way more play when I go to press it. It didn’t do this on my 2020 C300 and it’s not doing that on my 2019 C300 loaner. I would caution anybody from getting this car at this point.
This is day 3 at the dealer today, still with no word as to what they are doing with the car.
Last edited by Dstopsie; Jun 10, 2022 at 09:26 AM.
Senior Member
Joined: Nov 2016
Posts: 265
Likes: 54
From: Los Angeles baby!!
2020 C300 Sedan
After 13 days of being at the dealer I finally got my car back yesterday. They finally determined that both the front brake pads and rotors had to be replaced on a brand new 2022 C300 with 99 miles.
This whole thing is such an ordeal because the dealer can’t just repair the car. They have to open a PTSS and then communicate with MB engineering in Germany which can only be done via email. My car was actually ready on Monday the 20th but they couldn’t release the car until MB engineering said it was ok. There have been quite a few other cars with this same issue in the US and Europe according to my dealer and they are just coming to light as cars are being delivered. My service advisor who got a brand new 2022 told me that his car started doing this also.
I still feel this happened because these cars sat for 7 months before being delivered to dealer.
This whole thing is such an ordeal because the dealer can’t just repair the car. They have to open a PTSS and then communicate with MB engineering in Germany which can only be done via email. My car was actually ready on Monday the 20th but they couldn’t release the car until MB engineering said it was ok. There have been quite a few other cars with this same issue in the US and Europe according to my dealer and they are just coming to light as cars are being delivered. My service advisor who got a brand new 2022 told me that his car started doing this also.
I still feel this happened because these cars sat for 7 months before being delivered to dealer.
Last edited by Dstopsie; Jun 22, 2022 at 02:24 PM. Reason: Typo
Senior Member
Joined: Nov 2016
Posts: 265
Likes: 54
From: Los Angeles baby!!
2020 C300 Sedan
So far no. I didn’t drive it much yesterday because I went home and cleaned it. Since it sat at the dealer for 13 days it was dirty and I never let them wash my car.
I did drive it father today and so far no clunking and thump. Keeping my fingers crossed this is a permanent solution. But what is normally a one day repair took 13 days. I was so glad they heard it doing it when they drove it. Luckily the dealer told me
the parts are available.
I did drive it father today and so far no clunking and thump. Keeping my fingers crossed this is a permanent solution. But what is normally a one day repair took 13 days. I was so glad they heard it doing it when they drove it. Luckily the dealer told me
the parts are available.
Super Member
Joined: Nov 2008
Posts: 604
Likes: 29
From: SA
2008 C350-Sport-AMG-Active Agility Pack(Not reliable) +Izuzu KB6 3L(It seems Reliable)+Mazda
Maybe not your problem but it was an interesting one
On another vehicle I had the shocks replaced. I then started hearing a clunking noise on roads with certain surfaces. I took it back, the dealer found no fault, we also push front end up and down no noise, nothing loose at suspension either, thorough checked.
Then a week later I reversed fast out of my garage and as the front wheels go over a wooden strip to keep water out at door, I heard the clunck. I found I could repeat it in garage but not necessarly on any road.
I reached out to front shock manufacturer, they said they will replace them free of charge faulty or not. I got the service manager with me and prove to him the clunk every time out of garage over strip, and with e-mail from shock dealer eadoffice, he replaced both, and problem solved... So the shock needed a certain frequency to clunk and they were new.
On another vehicle I had the shocks replaced. I then started hearing a clunking noise on roads with certain surfaces. I took it back, the dealer found no fault, we also push front end up and down no noise, nothing loose at suspension either, thorough checked.
Then a week later I reversed fast out of my garage and as the front wheels go over a wooden strip to keep water out at door, I heard the clunck. I found I could repeat it in garage but not necessarly on any road.
I reached out to front shock manufacturer, they said they will replace them free of charge faulty or not. I got the service manager with me and prove to him the clunk every time out of garage over strip, and with e-mail from shock dealer eadoffice, he replaced both, and problem solved... So the shock needed a certain frequency to clunk and they were new.
Senior Member
Joined: Nov 2016
Posts: 265
Likes: 54
From: Los Angeles baby!!
2020 C300 Sedan
That’s interesting. Mine only did it braking. And it was on the drivers side only. They were able to isolate the sound by “connecting chassis ears”. They also found “glue on the brake pads to have reduced holding force” per the invoice. They said the sound was isolated to the left front (drivers side) wheel hub area.
just came back from a 16 mile drive and the braking was fine, no clunk and/or thump when braking at all.
just came back from a 16 mile drive and the braking was fine, no clunk and/or thump when braking at all.
Senior Member
Joined: Nov 2016
Posts: 265
Likes: 54
From: Los Angeles baby!!
2020 C300 Sedan
take it into the dealer. As you know from this thread my car started it 3 days after I got it. They replaced the front brake pads and rotors and so far it’s been fine. The worst part for me was it took them almost 2 weeks to fix it cause they have to report it to mb engineering in Germany who requires they take photos and videos of the rotors and pads. Let your dealer know there are other people who have had this. Myself and another forum member that I was in email contact through this process in WA had the same issues.
let me know if you need any other info from me. Glad to help.
let me know if you need any other info from me. Glad to help.
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Junior Member
Joined: Jun 2022
Posts: 57
Likes: 12
From: Sacramento, CA
2022 C300 Sedan
Looks like my car has this issue too. Noticed it today when I had to brake a bit quicker than usual for a signal light. I’ve had the car for about 10 days so far - maybe 160 miles on the odometer.
Junior Member
Joined: Jun 2022
Posts: 57
Likes: 12
From: Sacramento, CA
2022 C300 Sedan
Update. Took my car to the dealership for the brake issue on Wednesday. Yesterday they called me and said they believe it’s actually an issue with the steering rack. They are in contact with MB and will be hooking up the car so MB can analyze data etc. As of yesterday they were thinking the steering rack would need to be replaced. If that happens then likely will be at least a week before I get the car back. Still wondering how the steering rack could be causing the thumping sound when braking. I’ll ask about this again when the service advisor calls me back.
Newbie
Joined: Sep 2022
Posts: 6
Likes: 0
W206
I had this issue as well. It happened to me as i step harder on the brake pedal progressively. I can hear " thump, thump, thump" repetitively as i step harder. This is the second time that this had happened to me. I have faced this issue twice. First occurrence was resolved after dealership replaced the rear right brake caliper. Rear left caliper was replaced after the second occurrence. Besides this, i encountered many other issues with the W206 as well. Moral of story is to never buy the latest model cars 
Member
Joined: Jan 2022
Posts: 142
Likes: 21
C300
I had this issue as well. It happened to me as i step harder on the brake pedal progressively. I can hear " thump, thump, thump" repetitively as i step harder. This is the second time that this had happened to me. I have faced this issue twice. First occurrence was resolved after dealership replaced the rear right brake caliper. Rear left caliper was replaced after the second occurrence. Besides this, i encountered many other issues with the W206 as well. Moral of story is to never buy the latest model cars
