2006 CLK 350 Rattling Noise at Idle
 

Hey there everyone! I've recently begun experiencing a rattling/tapping noise at idle in my 2006 CLK350. The car has a little over 190,000 miles. The noise can be heard in and out of the cabin, but the cabin noise is fairly muffled. Using a long crowbar with the serpentine belt disconnected, I have isolated the source of the noise to around the water pump area. Sounds more prominent on the right (passenger side of the engine), and it is certainly coming from the front. My thought is that the timing chain could somehow be making this noise. When I listen into the valve covers, there is no abnormal noise.


Any insight into this issue would be awesome.

Thanks,
Owen

Hello. I seem to have the same problem and looks like it's the tensioner pulley. Did you fix the problem and how?

My boys E350 2009 makes a similar noise at idle. If you step on the gas a little does it go away? It's been doing it for quite some time and it never gets worse. I think the timing chain failure sounds different to what you are experiencing. It could be low oil pressure causing the tensioner to bounce.

Check the egr system
 

I had the same issue it sounded like the timing chain was slapping but I ended up changing out the secondary injection pump for the egr system and the sound went away completely. In the photo below I circled the component
https://cimg5.ibsrv.net/gimg/www.mbw...2207161696.png
06 w209 500