Infamous C63 Idler Pulley Grenade
 

So, my idler pulley closest to the top of the engine gave out and it also happened to take out a hard plastic clip that feeds coolant to the engine from the vent hose. This part sits directly on top of the idler pulley. This clip is actually inserted into the engine. If you look at the diagram, it's a black clip that the hose is inserted to the hose farthest to the right. Below is the information for reference:VENT HOSE - MERCEDES-BENZ (204-500-03-72)



I tried looking for a part number, but can't find one. Can anyone tell me the part name at least so I can start digging around? Thanks!

Syntax - Sorry to hear and GL but would you be so kind as to state the mileage when this happened? Thanks.

Mileage is at 108k.

you talking about number 70?
https://cimg1.ibsrv.net/gimg/www.mbw...77660b2a45.png

I'm actually talking about the #45 idler pulley. There's a plug right above or next to the pulley that feeds coolant from the vent hose that leads to the coolant reservoir.

take a picture of it, i'll compare it with what i find.

Will do and I appreciate it. In response to that diagram you showed me, the part actually connects to part #280.

As you can see, the nose of this part broke off.




Attachment 441669




Attachment 441670

Attachment 441671

Please post or PM me your VIN and I will hunt it down on the MB site.

Sorry to hear OP. #45 was also the worst condition one when I recently replaced mine with the Weistec billet idlers. Good preventative maintenance to replace every few years or with the Weistec upgrades, because they give no warning.

We have the M156 billet idler pulley kits in stock

http://imagizer.imageshack.us/v2/xq90/923/HmNVIP.jpg

Is it possible it's part of number 45 on the attached pic? If so, it's part number A 156 203 04 75. If not, I'll keep looking.

It's definitely a part of #45. I can actually see the part right under #60.

A nearby coolant hose isn’t going to be part of the #45 idler pulley

I figured out that part #45 is a thermostat and the piece that broke off doesn't come separate, so I had to order a new thermostat. Thanks for all of the help everyone, much appreciated!

I checked my idlers last year at 29K miles on my bone stock 2012 and both idlers #45 and 65 had rough bearings so I replaced them all with stock ones because I hadn't heard of the billet option (hadn't found this site yet.) Do the billet idlers actually have better bearings or just look better than the MB plastic ones? It is great that this site can help us folks who are wrench turners but don't have deep knowledge on the C63. If we can avoid having failures that not only strand us by the side of the road but also damage other parts of the car it is well worth the effort!
Thanks
Jim

Better bearings that are serviceable versus the one-time use of the OE ones. Much quieter.