Hello,
I have a c300 with 18K miles and have noticed a knock for 2-3 seconds on start-up. It is pretty noticeable and goes away after 2-3 seconds. I'm taking it back to dealer on Thurs. morning. Service advisor said he has never heard of this problem before. Anyone have this problem.
Thanks,
Miguel

 

Causes of startup noise in Benz engines (apart from at oil drain)

- Bearing noise (mainly small end) clearance - requires repair
- Piston slap due to ultra short skirt pistons - fine if slight and stops at operating temperature. Benz metallugy maintains fairly consistent piston to bore clearance with temperature change unlike engines with iron blocks or liners.
- Timing chain slap prior to oil pressure reaching max. - Hydraulic tensioners require repair.
- Camshaft adjuster rattle - require deburring or replacement.

Good luck!

 

My 2008 did this all the time too until I traded it for my 2011. My 2011 doesn't do this at all but I was told it's normal by my dealer.

 

Mine does it also, I also though it was the fuel pump ?

Let me know what the outcome is. I Never though anything of it but if it's a serious issue I better take it to the dealer so it's cover under warranty

 

This subject has for a long time been the subject of many threads in the W204 forum. Suggested is first searching the forum for the answers before initiating new threads, which are redundant and confusing.

https://mbworld.org/forums/c-class-w...ine-noise.html