michail71

I'm not 100% sure but if it were the turbo it most likely would not do that in neutral. Turbos with aftermarket intakes don't usually make much of a spool sound at neutral.

I had a heavily modded VW car, so I'm overly familiar with what turbos sound like and this Mercedes is louder than my after market modded VW? I think not, lol.

Also, I believe both of us traced the sound to the front right side of the engine. The turbo is on the back bottom left.

Volkswagen makes nearly silent turbos, so I would think Mercedes could as well. Plus turbo sound is usually a deeper woosh.

michail71

Here is another test to see if it is the turbo. Try downshifting while coasting. If you hear the sound just the same it's not the turbo. Turbos will only build boost with fuel as it's exhaust gases driving the turbo charger.

mercc250

So I get a call from the dealer last week and he said the service expert has checked each and every bit in the car and didn't find anything wrong with the car.
I had highlighted the Pulley tensioner and the pulleys from my end itself to assist.
They said everything is fine and the service expert had driven my car and found all the sounds and noises are normal and that is how a c250 should sound. He also drove another c250 and compared the sounds and my car sounded exactly like the other one.
On my insisting I got an appointment with the service expert to make him sit with me and drive around so that I can state my pain and / or if it is possible for them to make me sit in the other c250 to hear the sounds myself.
He scheduled it for me.
So I go to the showroom and made the service expert sit with me and made him hear everything. Darn the car sounded less weird with him inside (they always do that when there is a mechanic around). He said this is all normal, the c250s sound like that. I wasn't convinced.
Then I insisted on the other piece of the deal to sit inside a c250 and hear.
The Dealer held that piece and made me sit in a CPO 2014 c250 18k miles done and I rode with the service expert.
It was all the same. The grunt the whine everything. It got better when the car got warmer which happens with my car too, Warmer the Better.
All I was left was take my car back as I had no more cards to play. I am not that comfortable but yes I am trying to live with the sounds and ignore them.

michail71

Hmm, my tensioner was bad and the dealer replaced it. They took me for a ride in it but had to keep the car. It does still have a slight whine but nothing like before. I'd say it sounds 25% of what it had. They said they have been seeing the tensioner issue in some C250s.

I have one of the 2.0 turbos in my loaner. It's one of the loudest OEM turbos I've heard. It makes a groaning sound. I actually prefer it to the whine.

mercc250

Okay, I still have the light knock knock...and faster when I accelerate from the halt. But I did hear the same in the other c250 I road in. Did you ever or do hear the sound?

michail71

I'm not sure if I have that. I still have the GLA loaner. I can't wait to get my car back. I'm really starting to hate the GLA. It's taking days to diagnose and fix the navigation system.

c204coupe

from the sound I hear on your clip sounds normal to me, sounds like the transmission hum which will resonate through out the car. when you made the sound clip where you in 1st the whole time?

mercc250

well I think this occurs only when the car tries to gain speed for that particular gear, like uphill / halt -> speed. . As I you might have read, I checked with another c250 in the sale lot at the dealer. He did me a favor by making me ride in one of the 2014s which were half on mileage as mine and it made exactly the same noise.


I am pretty convinced with the service expert telling me that it is the mechanical fuel pump which makes that noise in the c250s. But really a Mercedes fuel pump makes such noises? I don't have any other way to check if my car is bad on something as they checked everything there inside the hood and its all fine.

michail71

No, this one it engine RPM related. At least for me it was.

My car has been at the dealer for a month now (for another issue). I briefly drove it after they fixed the tensioner but the wine is still there to a slight extent. I haven't been able to gauge the improvement too much yet but it's just nowhere as bad. I think the noise issue is just related to the serpentine belt system.

Danc90

My '08 c200 makes the same RPM related sound, but only When the air conditioner is on. I had my air-conditioner re-gassed at the dealer, the noise subsided a bit.

michail71

I think I should get my car back tomorrow. So I'll be able better to gauge the fix to my tensioner.

mercc250

Great, if it is possible for you can you record a clip from inside the car while you drive so that I can listen to sounds and compare them. A low speed uphill or a signal halt and go might be helpful


Another thing do you have staggered wheels? Mine runs at 225/45 R17 in the front and 245/40 R17 in the rear. I doubt if I can get a tire rotation on these!

michail71

Yes, I have staggered wheels.

Sadly I still don't have my car back yet. Even though I have a nice W205 to drive around I miss my car. The W205 drives nice, is queit and they fixed the stupid laggy throttle response. But the designers took a step in the ugly direction.

michail71

I have the car back finally!!

Yes, there is a whine still present in the car but it is nothing like what I had prior. It makes the car much more pleasant overall. I've also been in a W205 C300 for a while which is a very quiet car.

I had the upper guide pulley (000-202-16-19) replaced.

mercc250

Great to hear that. I will let you enjoy the comfort of your car and whenever you are good just upload that sound clip which I had requested.


-> Inside the car -> low revs or halt to speed. I would like to hear what it sounds like when you strain the car to bring it up to speed.

michail71

Sorry I haven't gotten a clip up yet. The car is still in and out of the shop.

I heard a car with a loud whine pulling up along side me. Same kind of sound but much louder. Sure enough it was a C250.

While my whining has been reduced it's still rather annoying. For the first couple days I was happy it was quieter but then it started getting to me a little. It's kind of startling to think Mercedes has made one of the worst sounding engines in recent production.

It's mostly low speed driving where it's bad. If you can gun the car from a stop to 40+ MPH it's not that noticeable. But drive 25 MPH though a neighborhood and it sounds like you're driving a tank as the whine overpowers the engine, exhaust, road and wind sounds.

mercc250

Totally agree to the last statement you have made. I have been a cruise driver even at low speeds with less gas but this one makes me uncomfortable while doing that. It whistles loud, and the grunt sound it makes while acceleration whenever required. My first post stated the same, when it moves it should move like a Mercedes not like a Mustang. I have driven a rented 2015 Mustang and the grunts and whistles were there and I some how liked it but with my c250 I didn't expect that at all no wonders the time I drove it post purchase I wasn't so icky on the sounds.

michail71

I guess driving through a neighborhood is something we typically don't do on a test drive. I's gun it a few times and drive around the dealership.

I have to wonder if there isn't something that can be done about it. I still think the issue is somewhere in the serpentine system. I may try getting a mechanic's stethoscope to investigate a little more.

You can drive the cheapest econo cars on the market and they will be rather quiet under these conditions.

spb147

Hi everyone,
sorry to revive this thread again, I'm just wondering whether anyone has experienced a rattle similar to mine. my cars been experiencing a loud rattle at low rpms for a while now (two YouTube links attached below). usually after 20-30 mins of driving, the car makes a loud rattle at around 1250 rpm when maintaining the revs there or coming down the revs.
the longer the distance I travel the louder the rattle becomes and going either uphill or downhill exaggerates/increases the sound.
regardless of whether I'm driving or have the car parked in N or P, the car makes a rattle at about 1250rpm. ive attached the videos below from both inside the car and from the engine bay - also linked my thread and another one

any help or suggestion would be greatly appreciated!

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

https://mbworld.org/forums/c-class-w...w204-c250.html

Inside the car
https://www.youtube.com/watch?v=OptN...e=emb_imp_woyt

from engine bay
https://www.youtube.com/watch?v=yIks...e=emb_imp_woyt

Odd Piggy

When I open the engine bay YouTube, it has a time stamp 4 months ago. Am I picking up the right video?

spb147

yes, thats correct. Thought I might explore other thread that may have potentially had the same issue to find a possible solution!