JeruC350

I've recently started hearing a very light "hallow" sounding tap/pop after coming to complete stop in my '08 w204. It's only a single tap immediately after the car stops 100%. It sounds like its coming from under the car but I've been unsuccessful pinpointing its source. I have checked for loose items.. Checked the spare tire.. But no luck. I have found that the noise did not occur if I stopped the car after after shifting to neutral gear. Possibilities that I've come up with through my research thus far are u-joint/driveshaft , transmission, and someone actually told me that it is normal... That its the adaptive brake assist working as it should, and that taking it out of gear (shifting to neutral) disables that particular feature which is why I don't hear the noise when doing so. So I'm stumped. I know for sure that if this noise was always there I would have noticed it before now. Also, after the noise occurs the brakes do not prevent the car from rolling forward or backward.. Which now has me thinking that the noise could be that the brake assist is NOT working properly. Good thing is that the noise happens every time I stop the car after driving 35mph or higher so reproducing it for a dealer will not be a problem. I'm just hoping someone here may be familiar with this issue and assist in clarifying or narrowing down the possibilities. Thank you all in advance.

JeruC350

Ok.. So I took my car to my dealer to have this noise checked out. Both my SA and mechanic heard the noise I was referring to and looked into its cause. After investigating they were unable to explain the noise. We then took a ride in a 2008 C350 off of their lot...identical to mine except for the color... And it made the exact same noise when coming to a complete stop as my car does. Ultimately they chalked it up as a characteristic of the car. Does anyone else on the forum with a 2008 C350 (or C Class in general) experience this same noise? It really only happens after traveling above 35-40 mph and coming to a dead stop. It's a very faint pop sound (louder at certain times) that can be heard clearly if the cabin is quiet.. No A/C, no radio, and windows up. Just a single pop like a tap on something hallow. I'm dying to know what this noise is. The fact that their car made the same noise makes e believe that it very well may be a characteristic of the car that I just never noticed before. I mean what are the odds that both cars had the same exact problem? However it's still isn't enough to ease my mind. I really would like to know if anyone here has this experience and if so, do you know what it is that causes the noise? Again.. Thank you all in advance.

2006_C350

No clue what that noise is but my 2010 C300 does that too and they changed the suspension joints but it still makes that sound. I am thinking it might be a bad shock/strut that makes the noise when you come to a complete stop a little too fast.

If my hearing hasn't gone bad yet the sound is coming from the front passenger side of the car right? It sounds like it is coming from underneath the front passenger side of the car. It really makes me feel like it might be suspension related and it is really annoying. I would have noticed this from the beginning when the car was new if it was a "characteristic" of the car.

Did you have your brake booster changed?

2006_C350

ok finally found a dealer tech that told me its the brake pad shifting that's making the noise and I could pay him 2.5 hours to lube and grease everything but the noise will come back...

JeruC350

Hi 2006_C350.. it sounds like you are experiencing the same noise that I am. My noise also sounds like its coming from the front passenger side but sometimes sounds like its right in the middle of the car.. between the front and back seats. I've already had the brakes checked, cleaned and greased and it didn't help at all. I can now rule out that its the brakes because I have found that if I shift to neutral before coming to a stop the noise doesn't happen at all. Maybe you should try that and see if yours doess the same. I definitely think that the problem is somewhere in the drive train. In addition I've found that the noise has started to happen at random times when I slow down to a near stop and then hit the gas petal to accelerate again. I hear it as soon as I give it gas. I hear the noise much less frequently when driving in wet conditions such as rain. I am dropping my car off at the dealership today to have it looked into again. I've come to the conclusion that it is not a characteristic of the car since, like you, I also know I would've noticed this noise before had it always been there, and I'm pretty sure that you and I wouldn't be the only 2 people so far in this thread. Anyway, I'll update this thread with the results of my dealer visit. Hopefully quickly. Best of luck. Please let me know if you find anything out as well. Thank you.

2006_C350

Well, the dealer changed the ball joints in the front but that still didn't solve the problem. I don't think I experience the noise in the middle of the car, but mainly in the front right of the car and this noise just started right after I got the car back from the dealer and they changed the brake booster and did a brake fluid flush. At first my brakes felt like there was no resistance at the top and I had to brake farther down to stop the car but that experience has disappeared.

Please do update me as to what your dealer finds.

My car is a 2010 C300 and I see yours as a 2008 C350.

Are you out of warranty?

Where are you located? Maybe we can meet up. I'm in Los Angeles.

JeruC350

I had my car in to have the drivers side rear wheel bearing replaced and also to have the comand module replaced because it stopped scrolling. I noticed the noise right after having this work done. My warranty was out last June, but i have a service plan that i am now very happy i decided to get. im in Tampa so unfortunately its a bit too far to try and meet up with you. Like I said before, you may want to try and shift to neutral before you stop your car and see if the noise still happens. Ive never heard it once when doing that, which makes me believe that it can not be the brake system. I actually thought of trying it when I got into my car one day and heard the exact same little pop noise, just very very light though, when I shifted into reverse to back out of the garage. It sounded like it happened when something engaged when I put it in gear, so I thought that it may not happen while stopping if I took the car out of gear. It didnt. So hopefully Im onto something with that. I took my SA for a ride when I dropped the car off today so he could hear it. Im sure that Ive heard it come from behind me at certain times, especially when it happens louder than usual and when i had my wife drive and i sat in the passenger seat to try and listen from a different spot. In either case its very difficult to pinpoint exactly where its coming from though. Its been driving me nuts. Its been at the dealer for several hours now and I have yet to hear anything.

JeruC350

Well.. I got my car back from the dealership. They explained the light pop noise after coming to a stop to be the differential, which according to them is normal. They also drove another 08 c350 on their lot and confirmed that it made the same noise as mine. This is the 2nd time a dealer has confirmed the noise in a like vehicle from their lot. My car wouldn't reproduce the rare "louder" version of the same noise so they couldn't make any diagnosis on that. Basically told me to keep an eye on it and try to figure out exactly what conditions the noise occurs. They also said to try and record it with my phone.. which won't be easy to do. I still feel that even the subtle pop noise that is supposedly the diff wasn't always there. I'm 100% positive I would've noticed it before now. It also just doesn't seem normal. I've owned several vehicles, none of which made any noise like this. Plus i think there would be many more posts about this noise if it was a "normal" occurrence. I'm really not sure where to go from here. Seems like I've exhausted every measure I could at this point.