Mercedes-Benz W204 Drive Belt Replacement - (2008-2014) C250, C300, C350 (2024)

Good write-up. One thing to do is mark the direction of the old belt before removing if you plan on keeping it as a spare, they say a belt will wear and adapt over time and you want to reinstall it the same way. I noticed this when inspecting the old belt, it is worn differently on the sides. The old belt is still in good condition so i cleaned it and put it in with the spare tire and 17mm lug nut wrench if the new one ever breaks. While looking for the correct belt I was told 6PK2404 so thats what I bought, only to find the belt that was installed was 6PK2390. I installed the 6PK2404 and the line on the tensioner is between the two lines towards the left, seems that's right where a new belt should be. I didnt even bother to check where the line was with the old belt, wish I had. What i'm also finding is Mercedes belt 6PK2397 as fitting my 2010 C300 4matic Sport 272. I guess they are the same belts just slightly different lengths.

Thank you so much for posting this! The pictures were very helpful - I used them to reference the path of the belt when putting on the new belt.
This was the first time I replaced the belt on my own. With really taking my time, setting up some good lighting, and taking pictures first, it took me about half an hour. My vehicle is a 2011 GLK350 4Matic.

Thank you!

After recently replacing the belt for the 3rd time in 4 years on my 2011 ML350 4Matic 3.5L V6, I noticed "marking on the tension side red arrow" is NOT "between the marks on the mounted side yellow arrows when the new belt is installed see pic. I've suspected for some time one of the component water pump, AC compressor, alternator, power steering pump pulleys is causing the belt to shred prematurely. In between belt, pulley and tensioner replacements, I've had the water pump and recently alternator replaced. In ideas regarding what might be causing frequent belt failure would be much appreciated.

Thank you so much for the instruction, it helps a lot. I got the same problem which AlyssaRae got, my car is 2010 glk350, the marker on the tensioner side is postion on the left side wider marker of mount side, the belt and temsioner are the right parts, please help. Thanks in advance.

Your guide is very useful. But I had a trouble: I installed a brand new belt Contitech 6PK2404,all elements are OK no damages, or misaligment, tensioner is OK between marks... and just next day this belt was completely destroyed without apparent reason...help please! Thanks! W204 c350sport 2008

I replaced the tensioner along with the belt and another pulley. Without tension the mark on the tensioner is to the right of the two marks. With tension it is to the left of them. The old tensioner was the same way, which led me to replace it. Wondering why the mark does not line up in the middle. 2010 c300 4matic

In what direction does the engine rotate? Clockwise or counterclockwise? I'm replacing my timing chain and need to put it back In OT position.

is there a way to adjust the belt tension to between the marks on Figure 4?

I did 95000 km on c220cdi 2009 australia

Your diagram and instructions are spot on! Thank you very much for posting them. Not only did you save me money by doing it myself, but your description along with the pictures made it very easy and straight forward to do. It took me all of 10 minutes. Thank you very much, indeed!

You can also use the factory-supplied 17mm lug wrench from the vehicle tool kit in lieu of a 17mm socket and ratchet/breaker bar. It is definitely easier with a longer ratchet or breaker bar, but it can be done with the lug wrench in a pinch.

What's the name of the small little pulling next to the tension