Had an interesting day. 121,000 miles on my CL55.


Driving home, and was a little less than 2 miles from home and my dash lights up like a Xmas tree.

Ding..... MFD shows in red, Battery not charging - Visit workshop!

Ding..... MFD shows in red, ABC Suspension - Visit Workshop!

Figured a broken accessory drive belt let go and I would try to limp the CL home.

Power steering gone...... Argh....

1 block from home and

Ding..... MFD shows in red, Coolant HOT - Stop Engine!

Pulled into my driveway, popped the hood. Drive belt shredded all over the place. Coolant just starting to leak out of the overflow bottle pressure cap.

Whew, made it home just in time. Stopped in the driveway and later pushed the car into my garage.

The culprit was a broken belt tensioner pulley. These tensioners have been superseded numerous times over the years so I will pick up the latest part tomorrow with a new drive belt and install.

glad you made it home in time!!!

Should be a fairly easy DYI fix. It just happened to my SL500 (also a M113 engine) about couple weeks ago. I was "luckier" because it broke before I left my house for work just minutes after I started the car.

How many miles on your odo ?

had the same thing happen to me in August in my CL65, x-mas lighting effects and all on the dash. Separated pulley, belt displaced, coolant overflow. Cost me a new radiator, hoses, pulley, and belt.....and about 2500 between all that and the labor.......for a friggin lame pulley breaking......also was about 10 days in the shop as they had to fly in the pulley and radiator from germany.

What happened to your radiator? Did you drive it for a while running too hot ?

what type of mileage is it typical for this problem to surface?

That is partially what I am trying to ascertain via the questions asked in this thread. So far, I have heard from 4 others that have had their tensioner or puller fail at approx the 110,000 mile mark on average.

wonder if preventive maintenance would be to change the tensioner at 90,000 mi. how expensive is the tensioner and how hard is it to replace?
thanks

I would recommend 100% ! The tensioner from Mercedes MSRP is $240. You can find it for less than half of that OEM.

Two bolts and the tensioner comes off/on. Simple but a bit cramped.

My idler pulley snapped off a month ago. Lost my belt too. It's made out of plastic..

102k now.

Happened to me too. That plastic idler pulley stranded me. I thought, "Wow, really, had to use a plastic pulley on a $100k+ car....POS!!!"

checked, the pulley is like $29. the tensioner is like $179 on line. can you get away with just replacing the pulley?

The first few generations of the tensioner had a metal pulley. My guess is that the latest generation switched to a plastic pulley as a break away means when/if the bearing seizes.

In my opinion, the bearing is toast around 100k as well as the spring which tension the entire belt. Best bet is to replace the entire unit and not worry about the bad things that can happen from a failure.

Pelican Parts, one of our forum sponsors sells the Litens units (Same as Mercedes OE) for $107.75

http://www.pelicanparts.com/cgi-bin/...13.991-%20Left


They also have the Febi unit for $77.75

http://www.pelicanparts.com/cgi-bin/...13.991-%20Left

94087 when it went bad.

No, I was pretty close to home when it all happened. I did get a bit of coolant overflow from expansion tank but who knows. Honestly, I think that it was "wrench" error when they went to install the new pulley because prior to that the car has no radiator issues at all. After I picked car up the next day I noticed a small amount of coolant on driveway, drove to church and got a check coolant warning (coolant reservoir was fine --3/4 full). Took it back to the shop next day and it was during that diagnosis that I got told the radiator was cracked. Car had 60k on it......pathetic for a radiator to fail at that mileage---pulley too if you ask me.

To ad to the conversation, my w215, 05 mantainace book says to replace the poly v belt tensioner for the v12 at 60,000 or 4 years. Think I'll get mine done soon respecting the 4 years,despite my 21,000 miles.

Mine is gone at 82k.

My car is at 80k+ this sounds like good preventative work.
So it's the pensioner and the pulley that need replacing- right?

Might get this done at my 90k service.

Now I may be being dumb here but at last service work, merc changed the supercharger pulley and belt- different pulley, right?

Correct. The super charger pulley is known as the Right tensioner. The accessory pulley/tensioner is the Left tensioner. It is about a 3rd of the cost of the supercharger tensioner.