Serpentine Belt tensioner

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Silversaab

New Member
Joined
Mar 23, 2021
Messages
4
Location
BT621NP
Car
Mercedes S Class 320 W221
Hello Gentlemen,
I drive a 2009 S class W221 320cdi.
My drive belt (Serpentine Belt) started to fray today. I checked on line for tools required , bought a belt and got stuck in. Unfortunately my tensioner does not have the normal 17mm Hexagonal bolt to enable me to release the tension on the belt, but instead has a multi face bolt as shown in the photo attached. Does anyone know what type and size of socket fits this. It isnt a Torx so i am at a loss.

Any help would be greatly appreciated as im now without the car.
Regards
 

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You should be able to get a socket on that. I did mine but can't remember what size socket I used .
 
Thanks. Ive tried the 17mm and it just started to turn a 16mm wont go on. I'm a little concerned if i damage to much it wont be usable so was going to order the right fitment if i could find what to order. looks a liitle worn to start with !
 
You will need a double hex, a six point will not do it.
 
Thanks. Ive just looked them up and that's exactly what i need . Never heard of them before so thats my lesson for today. Is it a 17mm do you know ?
 
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can you not pop i to your local garage and ask 1 of the mechanics for a shot of 2 sockets, maybe leave something with them so they know your coming back
 
Thanks. Ive just looked them up and that's exactly what i need . Never heard of them before so thats my lesson for today. Is it a 17mm do you know ?
Yes it's 17mm, I use a swan neck spanner on the tensioner.
 
The swan neck spanner worked a treat. It didn't take long yesterday morning. Working in the dark with a torch when your tired is never a recipe for success. A fresh start in the morning with the spanner worked well had the job done quite quickly. Car running well thanks everybody for your input. Regards Silver
 
Glad you got it sorted 👍
 

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