I have an OM642 engined 2009 C350cdi T-Modell (220bhp, rebadged 320). 115k miles, full service.

Its developed a clunking noise from the engine on low throttle acceleration through 1500-2000rpm only.

Been to my MB specialist who found no error messages.

There are slight hesitations in the rev range but once past 2k rpm normal power, this is not a limp-home issue. EGR recently replaced to no improvement (the clunking predates this). no issues with DPF regen. All soft hoses checked and confimed intact.

Currently having to shift either side of the rev ranges (or just cane it everywhere!) but if I am trying to be gentle, around town for example it is a pain in the backside.

Any ideas?

 

Hello!
does it sound like the videos in these two posts?
Ive been experiencing something similar but not exactly a clunking noise - ive attached my videos here https://mbworld.org/forums/c-class-w...w204-c250.html

and there is another post that sounds exactly like mine

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

Hope this helps

 

It really is a noticable clunk no more than once a second when its happening. Think your old sliding cd tray getting obstructed as it comes out, I know showing my age..

Things I can also rule out,

I have a tuning box running up to 35bhp extra, it happens whether attached or not with no change in frequency or severity. I have K&N panel filters, returned them to standard, no change (although the clunks do sound a bit more muffled). I disabled the Swirl valves actuator using a resistor, no difference, although pick-up is improved so it goes through the 1500-2000rpm segment a bit quicker!

 

just to confirm, so the sound you're hearing from your car is similar to the sound I'm hearing from my car?

 

it may be audible enough from the video above from the engine bay at the 10sec & 50sec mark - its the loudest ive ever heard it from the video from inside the car at the 40 sec mark

You Tube

You Tube