Hey guys, I have been trying to self diagnose this sound since I got my car a couple months ago. It is a '19 coupe and I am the second owner with 30k miles. I didn't really notice this sound on the test drive but of course as soon as I drive it off the lot it has persisted.
It seems to be more noticeable when it is cold and does seem to be linked to the turbos. It sounds like a metallic flutter that gets louder as I accelerate and just as I let off the gas (loudest around 50-60mph) and low RPMs.

When I got the car it also had that noise that sounded like a goose was under the hood but it was fixed with a replacement pressure transducer. If I could get this noise fixed I would be so much happier with this car.
I am under warranty still but it is tuned with catless DPs so it's a bit of a pain to take it to MB service directly without having my tuner put everything back to stock. My tuner tried to diagnose the problem but he just isn't extremely familiar with this particular engine and its quirks so he was not able to. I'm confident he can do the repair for me but I would just like to get your guy's opinions on what parts exactly need replacing.

Please take a look at the video and let me know what you think..
https://imgur.com/a/lFQFPRL

 

If it is the wastegate rattle issue, which I'm pretty sure it is, would this aftermarket wastegate actuator fix the issue? From what I'm finding MB won't fix the issue since it does not effect performance, but the noise drives me crazy and is a bit embarrassing.
https://www.ebay.co.uk/itm/194964228619

 

Sounds like my wastegate rattle (pre-facelift). I thought the new turbos on the facelift fixed this issue. Interested in hearing about the aftermarket wastegate actuators, the dealers won't do anything to fix it. They will say that it is within spec and that the rattling is normal. But after bugging them so many times during my warranty period, they offered a software flash on the electronic wastegates that hold them closed for longer during low boost requests so that they won't be "partially open" and cause the rattle. P.S It didn't help and just wastes more gas by going into boost when not needed...

Judging from the very faint sound on the video, it also sounds like the interior AC fans may be rattling too. At certain frequencies, especially with the mufflers open, the fans can rattle when the car is cold -- bad tolerancing on the fans making it temperature-dependent.

 

The sound in the video is not nearly as loud as it sounds in person. It sounds like it is coming from near the pedals, but towards the engine. That's why I had my camera where it was.
I really wouldn't have guessed about the AC fans rattling. It sounds like metal on metal that is very linked to the boost.
I'm going to pull the trigger on the aftermarket actuators and let you guys know the results.

 

hey man did the wastegate actuator fix the rattle pls let me know

 

Sorry I haven't been able to install it yet. I've been waiting for another few parts that I am getting to save on install cost to have them all installed at the same time. I should be getting the last part very soon so hopefully I can get it installed by the end of this month, but with the holidays we will see.

 

Curious as well if the after market waste gate actuator fixed the noise. I have a similar sound occurring. Dealer is looking into the flex pipe mesh and also the turbo at the appointment. I had the passenger turbo replaced because of the issue but the driver side one still makes noise.

 

How’s urs sound?
I’ll try to get mine on here

 

On start-up there is a rattle for a few seconds as the revs are higher and the car warms up. The rattle slowly quiets as the car RPM's drop. When I drive out of the neighborhood surrounded by homes you can hear a metallic rattle from underneath the car bounce off the houses if the windows are down.

On my first road test with the dealer it was very noticeable and they were able to stop it by unplugging the vacuum or something on the driverside turbo. I went for another road test today and i think the car was closer to operating temp, and the noise was not as noticeable. They booked me in for an appointment in the next couple weeks to diagnose exactly what it is... Shop foreman said he could clamp down the mesh on the flex pipe which may help if it's what's causing the noise.

The turbo rattle we heard on the first test drive is normal according to them... But i don't understand why they would change the passenger turbo if it is a normal sound... Luckily turbo's are covered throughout the 36 month ELW so i am pushing to have that changed out. They tried to tell me the turbo was only covered in the first 24 months of ELW. My contract says otherwise...

I will try to get a video and share as well.

 

Here’s my bad noise

 

Don't see anything on your last post. Is it supposed to be a video or audio clip?

 

Here

 

That sounds a bit different than what I have happening. Yours is quite loud when driving. Mine is not as noticeable.

 

It’s noticeable when I put aftermarket intake on only.
If the radio is up can’t hear it
🤮

 

Yeah, I would go back to stock for the intake or try swapping for another brand. Something is off!

 

Or I’m a bad mechanic

 

I've been a little hesitant to post my results because as we added the aftermarket turbo wastegates, we also added CST cold air intakes, HPFP, and LPFP and retuned it. So I have a lot of new sounds but as far as I can tell the noise from the turbo wastegate is fixed, now I just have other weird noises that I haven't been able to diagnose but don't sound like they are related to the original issue.

I am pretty confident that if I only did the wastegates the sound I was trying to fix would be gone, but its hard to tell what else is going on in there now. I need to find a better tune shop in southern california that has more experience with these cars specifically because my tune shop is good, but I think it could be better.

 

I almost can’t believe this, but I was driving around last night in sport + and I didn’t get any of the cheap crappy noise.
I will check out tomorrow again, I was trying to get a buddy to hear the noise so I wasn’t just driving hard
not sure what is that different in + over reg sport

Figured I should add
the noise only stopped for a while.
It’s still there in any drive mode.

 

Did you diagnose this one by any chance? Your explanation is exactly my sound right now. Sounds like turbo chatter, not mechanical but hting & tinny like metals are hitting together. Noticeable a lot when cold, low revs, coming off the throttle at low speeds, especially when in a tunnel, next to houses or buildings.

Weird at 34k miles to have chatter so I'm curious if anyone fixed.

I'll try to get a video of mine & post.

 

My 2017 C43 makes pretty much the same noise that you described. Wondering as well if anyone found a solution for it.

I found this Mercedes bulletin online, which mentions it's not a defect, but they did produce a SW patch to change the wastegate opening programming: https://static.nhtsa.gov/odi/tsbs/20...02533-9999.pdf

 

Are you able to help me with this is issue ? I’m in Southern California and been working with EuroCharged and ACG auto motive and no one is able to fix my car. My turbos sound like rusty metal like the video you sent but the performance is horrible and feels like I’m losing power and a lot of vibration. Is there a way I can reach you on social media or something?

 

did you manage to find the root cause, i am having the same issue as yours

 

Sounds like it is. I went with a volvo part number that is interchangeable on an FB group's recommendation: PIERBURG 7.00782.11.0

 

Interesting that they share the same part.

 

Did the aftermarket wastegate actuators work?