60n5pt1

The guide pulley and the tensioner pulley are exactly the same but Stealership will not sell you just the tensioner pulley without the spring housing and the same goes if you searched for the whole assembly online.
Pulley alone cost about $70...the whole assembly about $380. Just simply remove the tensioner pulley (clockwise) using a 15mm hex and replace. DONE. You just saved $300 in parts. 30-45 min. job removing and installing
assuming you have replacement part in hand.

jvakos

60n5pt1 - was your tensioner pulley wobbling similar to mine as you see in the youtube video i made here? i dont know how to determine if the fix is to replace the pulley or the spring, or just buy the entire tensioner assembly (which is about $300 and i hate to do if only need the pulley or spring to fix the wobble).

Morphh

Take belt off and spin the pulley to see if it makes noise, mine was the the whole tensioner itself my bearing was fine.

jvakos

**Just tried to replace my belt tensioner and need some help with the new tensioner which wont budge!

I installed a new MB OEM replacement which is the recommended part for a C32 from FCP Euro (new belt tensioner part # A1122001070, old part #A1122000770) and it is identical which you can see from the attached pics.

I got the new belt tensioner bolted on after removing the old one and have the belt lined up properly to then release the tension off the belt tensioner, BUT that is where I am having an problem!!!!!

***For some reason the new belt tensioner will NOT release as i pull on it with a 10 torx socket and socket wrench...anyone ever deal with this???

So cannot remove the pre-existing pin that was already in the new belt tensioner when it shipped and cannot put the belt back on the new tensioner since I cannot release the tension on the new belt tensioner.

attached pics if its helpful to you

insame1

I don't get exactly what you are saying. Are you saying that the new one does not swing?

jvakos

Sorry i wasnt clear... but YES the new tensioner I got bolted on fine but when i put the socket wrench back on and try to swing or release tension to slip the belt back on it will NOT budge????

Could a new tensioner be that strong? to release the tension on my old one it was super easy, but of course that old one was shot and 10 years old.

insame1

It could be but it should have some movement. I know when i replaced the belt on my 32 getting it to slip back on was a pain.

FCPEuro

It sounds like you are going to need a tool that can provide some additional leverage.

--Kyle

Morphh

There is a pin holding it in place u have to take that out to release tension, I can see the pin in the pics pull pin out after its installed then use socket to pull it so u can put in belt, I would put new belt on too

insame1

Okay, i see now, you haven't been able to get the pin out. Hmm... what have you tried?

jvakos

Insame1 - so i figured it out. newbie as i've never replaced a belt tensioner before.

i bought one of these "serpentine belt tool" wrench which is like 2 feet long plus has an additional extension so gives you plenty of leverage vs my 8" socket wrench, so could could easily release the tensioner with one hand and then reach down to pull that retaining pin out of the tensioner pulley. the tensioner doesnt move or vibrate at all any more and there seems to be better response on the throttle perhaps because the tensioner is new and tight and the belt grips better (??) thanks all for the help on this.

Morphh

I had same issue with belt tensioner
Glad it's working now

jvakos

Finally got my new tensioner installed and can notice a better response perhaps because the belt is tighter due to stronger tension. Heres video of the OLD and NEW tensioner...the wobble and slack in the belt is gone!

C32 AMG belt tensioner OLD and bad wobble

C32 AMG belt tensioner NEW and no wobble

This repair is pretty easy. I tried doing this with a small socket wrench but could not get enough leverage on the tensioner torx bolt to release the tension and get the retaining pin in and out. I bought a 2ft long extension wrench (or "serpentine belt tool") to get proper leverage and easily could release tensioner pressure with one hand and then slide the belt on or off with the other hand...

FCPEuro

Glad to see it worked out for you!

--Kyle

purplecat001

Excuse me for bringing this thread from the dead OP, but can you tell me what the torque specs are for the tensioner pulley-without the spring housing- please? Hoping you are still active here!

Morphh

email rob @ needswing, I forget but he would know or it might be on his website

jvakos

purplecat001 - embarrassed to admit but i didnt find a torque spec for the bolts on the belt tensioner when i installed the new one. i didnt over tighten, but definitely eased it up pretty tight and no issues a year later.

let me ask the guy who's doing my engine swap (i'm down a piston in current original motor) if he knows the belt tensioner torque spec and i'll come back here shortly.... stay tuned

purplecat001

Jvakos- I was actually asking in reference to just the pulley on the tensioner housing. I believe you did the whole tensioner. If you know as for only the pulley onto the housing please let me know. Thanks anyhow.

purplecat001

Last night, I was digging through the MB repair software and found the attached PDFs. The OP was absolutely correct - the tensioner pulley part number is the same as the stock lower guide pulley. Based off of the diagram, (I think) it is stating 25nm for the pulley screw. If I am misreading it, please let me know.

I included the PDFs for other C32 owners looking to take on any of this repair with the tensioner.