The tensioner doen't have an adjuster. The cast hex head is used to release some tension so the pulley can be "pinned" so the mounting bolt can be removed.

 

Is what snapped off the 17mm hex used to release tension? You can use a T-45 or T-50 or whatever security Torx bit fits the tensioner pulley bolt to release tension.

Sixto
05 E320 wagon 213K miles

 

Yeah it was the 17mm hex that broke off, what steps would I take to do so? I've never done it before.

 

Sorry, I'm not familiar with the terms. Would there be another way to release the tension to remove the mounting bolts.

 

Belts are cheap. Cut it.

 

If I cut it, the tensioner won't go lower and cover the mounting bolt? I can still remove it right now without relieving the tension on it.

 

As Tabijan stated, try turning the pulley by using a Torx bit on the bolt in the middle of the pulley. If you're lucky, you will be able to PIN the pulley back so the tensioner bolt can be removed.

There is a hole in the backside where you can insert a screw or big nail to pin the pulley back so the tensioner bolt can be removed.

 

This might help:

Ideally you can use the pulley bolt to pin the tensioner. If the pulley bolt loosens before the tensioner can be pinned, remove the tensioner pulley, cut the belt (mind the whip!) then remove the tensioner bolts that are no longer blocked by the pulley.

Sixto
05 E320 wagon 213K miles

 

So I use a torx bit in the middle of this pulley bolt and turn it counter clock wise, then I pin it if it does move? Is that correct?

 

Yes

 

Be very careful when you do this, that torx can strip as it's not meant to take the load of that spring like the 17mm hex does

 

Should I turn it very slowly, also do you know what size the bit is? T30?

 

That's the first time I've seen one of those snap...generally, they're built pretty stoutly, those tensioner assemblies. You're going to use an OEM replacement and not a cheapo "made in China" one, right?

 

Let's hope. Could it be that the tensioner is frozen and won't spring?

 

I think it’s T-45 or T-50 and possibly security style with a post in the middle if OE. I don’t know what it could be if not OE.

An alternative to levering the pulley bolt and removing the pulley but I don’t know if safer is to press on a stretch of belt to move the tensioner to set the pin. Sounds like a two person job.

If you can’t get the tensioner to move and you can’t get the pulley bolt to loosen and the pulley rim is plastic, break the pulley with a grinder or big slip jaw pliers. That might give you tool access to the hidden attachment bolt.

Sixto
05 E320 wagon 213K miles

 

I removed the pulley bolt but now the tensioner is covering that last bolt I need to remove.

 

Ugh! MB really doesn’t want you to remove the tensioner while in tension. Can you get a pipe wrench or chain strap wrench on the tensioner arm? First douse the inside of the tensioner through the hole created by the hex coming off with PB Blaster or your favorite penetrant.

An angle grinder is tempting but you don’t want to be around if it hits the spring.

Sixto
05 E320 wagon 213K miles

 

I was able to use a swivel socket and get that last bolt out, it was a pain! The pulley uses a t40 bit by the way.

Another question are these parts okay? I mentioned earlier that I was going to purchase the gates tensioner, but all they had was a continental (litens) made in canada.

 

Litens is fine

 

What about the belt? Should I switch it back to a Mercedes one or is this one fine? The reviews don't seem too good for it online.

 

Continental Belts are also good.

 

Okay, thank you. I appreciate the help.

 

Name brand serpentine belts last a long time. If they break, it's usually because of a bad idler pulley or tensioner. I replace my idler pulley every 40-50K miles.

 

If you look at the Continental part casting I believe you will see who made it. Which I believe may be the OEM.