Drive Belt Tensioner
 

In driving the 98 ML320 today (after finally getting INTO it....) :-(
I noticed a new "noise".
Sounds like the drive belt tensioner is starting the groan a bit.

I haven't taken the belt off yet to see if the tensioner bearing is grinding or not, but assuming that's my problem, how difficult is it to remove the tensioner??

Thanks,

Barry

is it very noisy?
 

My friend had to replace that tensioner ($200 US part) because it was noisy... common problem in the ML...

It's not real loud, but it's starting to make noise and is certainly noticeable, particularly while at idle.

Assuming it's really just the bearing thats the problem, is the bearing replaceable without removing the tensioner from the engine first??

I'm assuming it's a bigger job than JUST removing that center bolt in the drive belt pulley......

Thanks.

Anybody have any experience with the belt tensioner??
Is is possible to remove the pulley without removing the entire tensioner assembly??
The center bolt didn't seem to budge in either direction, but without knowing if it can be removed or not like that, I was reluctant to put more "muscle" into it.......

Thanks!!

Barry:
If you mean the smooth pulley that is on the tensioner, i am not sure if that will come off or not, I assume so, but have never had a reason to.
The tensioner is held on by 2 bolts, it's not hard to change. I've always removed the fan and shroud to replace it, I forget if this is part of the officila work instructions or not, I've always done it to improve access to the bolts.
The hardest part probably is that in order to get to the lower bolt that holds the tightener on, the tightener needs to be "caged", which means you put a external torx socket on the stud on the pulley I believe you are talking about, and release tension on the belt. There is a nub on the moving part of the tensioner, this is brought back until you can stick a metal pin (a big nail might work) into a corresponding hole in the tightener bracket. Then pressure can be released on the stud and the tightener will stay in this position and the bolt can be removed. If you order the new tensioner, you will see what I mean because all the tensioners I have installed come in the caged position. After you install it you will release it from the caged position and can save the "pin" that the factory uses and will then have a good one to use if you have to do the job again.

Gilly

Ah, THAT explains it......
I was wondering......
It seemed like whether the belt was on OR off, I STILL couldn't get to that bolt........
I'll get into it this weekend.
Thanks Gilly. THAT is a great piece of information...... :-)

Barry:
I'd look at the new tensioner before you try to mess with it, it'll be alot easier to visualize what you need to do. The hole that the pin needs to go into is on the bottom of the tensioner, so you're almost doing it by "feel".

Gilly

I must say Gilly, your posts were absolutely dead-on.....
It WOULD have been much easier if I had seen the new one before I attempted to take the old one off.

The new one arrived and it all made sense.....

It's amazing though. It took me 1-1/2 hours of wrestling with and swearing at that "thing" to get it off, and 10 minutes to put the new tensioner on...... :-(

Works perfect now, and "quiet" too.... :-)

Thanks for your help and guidance....

Barry

Barry:
Been there, done that, I feel your pain.
I think I had the new one in hand before I had to attempt my first one. When the new one already had the pin in place, it was easy to figure out what I had to do. I have a nice collection of pins now, it makes it a little nicer to do the job with a left-over pin from the last one you did.

Gilly