Diablo_CLS55

Good evening. I started up my CLS55 after getting off work tonight, and after letting the car warm up no more than 10 seconds, I was greeted with a horrible noise. From inside the car, it sounded like a bottom end engine noise. Popped the hood and saw my belt tensioner wobbling pretty bad. Thought I could make it home and didn’t even make it an eighth of a mile down the road before I lost power steering, brakes and alternator charge. Opened the hood again and belt was completely shredded. Supercharger belt looked okay but might as well replace that too. Left the car parked. Going back in the morning to replace the drive belt, and tensioner. What tools will I need? First time doing this job on this car.

nd-photo.nl

If I remember correctly

- 17mm toothed spanner or socket for the supercharger belt tensioner
- 17mm socket and medium sized breaker bar for the serpentine belt tensioner
- 2 or 3x 13mm bolts holding the serpentine belt tensioner in place

If you have bigger hands/arms, then remove the fan to allow for more room

Pro tip: replace all plastic pulleys with aluminium/steel pulleys where possible!

Diablo_CLS55

decided not to do the job and instead had it towed home because I wasn’t gonna pay the dealers ridiculous price for parts. Waiting on parts from FCPeuro now. Will do the job when they arrive in a few days. Will definitely be removing the fan shroud. That’s the trick I did when I replaced the belt on my E550 which allowed me plenty of room to move my hands around

bbirdwell

Ensure you use the correct internal-Torx bit for the bolts holding the tensioner pulley to the block! I screwed this one up years ago and it was a Pain In The A** to remove the stripped bolt. One of the most inaccessible spots on the engine unless you want to remove the radiator and AC condensor. I was careless and used a Torx bit one size too small and stripped the bolt. Once I finally got the stripped bolt out I had to purchase another Torx bit to properly fit the replacement bolt as the size needed was not in the Torx bit set I originally purchased.

Pick up a couple of new bolts for the serpentine belt tensioner pulley and ensure your Torx bit fits correctly before attempting to remove the ones currently in the car.
003-990-16-12 drive belt tensioner bolt.

Yeah, the above should make it obvious just how painful it was...

Diablo_CLS55

Oh, I believe it. It was painful and took way longer than needed to just replace the serpentine belt alone on my E550…

Diablo_CLS55

Managed to replace the blower tensioner pulley earlier this afternoon before it got dark. Didn’t realize my blower idler pulley was also bad. Lots of play in it so now im waiting on that part to arrive as well. It’ll all go back together in a couple days… the longer and more painful part was pulling the birds nest out that was wrapped around the crank pulley…

nd-photo.nl

Good job!