sc57rider

Hello
my 2014 c220d does this knocking sound ( see attachements ) when I first start it in the morning,
knocking goes stays when I accelerate and almost disappears after half hour of driving, car runs fine though.
any ideas ?

edit: new video added

Cosworth2000

I can't hear anything. Is it coming from the inside of the car or outside of the car. Also, I only hear knocking when you move your phone.

sc57rider

you kinda have to put it closer to ear to hear it, it’s coming from the engine

Cosworth2000

Since it's diesel, try some engine cleaner before your next oil change or if its under warranty take it back to MB.

Keith66

I've not listened to your file, but mine (M274 2.0 gas engine) has done what you described since I bought it 5 years ago. At first I thought it may be something wrong but I'm thinking it may be normal (?). At least on mine, if it was a problem, I would think something would've happened by now.

Good luck!

sc57rider

any suggestions please ?

sc57rider

I attached a new clear video sir

denis550

I assume your car has the OM651 diesel engine. It's really hard to tell from the video but I think my car has a similar noise. If the noise is coming from the passenger side in the engine bay, in the general area of the turbo and filter housing it could be the turbo bypass valve. The bypass valve is made from metal and if the spring in the part looses tension, it can develop a rattling sound.
Here is a Xentry Tips document describing the issue https://static.nhtsa.gov/odi/tsbs/20...19692-9999.pdf
And here are videos describing the issue:

• You Tube
• You Tube

Mercedes made a new part for the turbo air duct and bypass valve made of plastic which should solve the rattle. I also heard of people elongating the spring in the valve to fix the noise.
Again it's hard to tell from the video, it could also be the belt tensioner or the chain/chain tensioner or many other things.

EDIT: Here is a thread from the W212 forum with a similar issue: https://mbworld.org/forums/e-class-w...old-start.html