Replacing the auxilliary drive belt

[wartime]

My C200 V-Reg 2 litre auto has now completed 38,000 miles so having the Haynes Handbook, I notice that the auxilliary drive belt should be replaced every couple of years. Mine is still original so I popped into Poole Mercedes last week and purchased one. As I understand it, the tensioner wheel is on a vacuum strut and with a spanner on the (weird) nut I can assert pressure, anti-clockwise, insert a bolt into one of the two holes, and remove/replace the belt. Is it as simple as that or is there any tips anyone can offer please? I'm a bit concerned about the type of nut on the tensioner as I'm pretty sure my conventional metric box spanners won't fit!
Thanks you, Barry

 

[C220GJS]

Use a 15mm,long ring spanner. Take note of the belt routing before you start.
The torx end on the shaft is only so the shaft can be held firmly to undo the nut when removing the pulley.

 

[wartime]

Re-Removal of Belt

Thanks but I'm not sure I understand fully your answer ie;

The torx end on the shaft is only so the shaft can be held firmly to undo the nut when removing the pulley.

Can someone please clarify what is meant. Do I have to undo this torx end bolt or does a spanner on it, pressing anti-clockwise, release the tension on the belt, which is what I am thinking. Thank you.

 

[C220GJS]

This is your belt tensioner;http://www.detali.ru/cat/oem_mb2.as....418&VIN=*&CT=M&cat=19K&SID=20&SGR=045&SGN=03 ;No.23 is the 15mm nut i am referring to.Just fit a long ring spanner to it and lever anticlockwise to relieve the tension on the belt,as you said.

 

[wartime]

Thanks for that. I was under the impression I had to disassemble the pulley unit rather than apply pressure to the left with a spanner to release the tension on the pulley. Incidentally, the nut in the centre of mine is one of those new star splined variety rather than the conventional metric 6-sided type. Thanks for your help.

 

[rapide]

belt / pulley/ change

26 on the diagram is plastic push in cover over the nut that holds the pulley on! that splined bolt is the torx head of the spindle that holds the bearing and pulley! dont try and undo it , it wont undo! its only to hold the spindle while you undo the other nut! if the new belt is a pattern one it may be tight and you can take off the pulley to gain some more slack! have go, the pulley bearing gets noisy anyway good practise if you have to change it; about £20 from mercs!

 

[wartime]

Thanks to both of you. I was able to use a conventional box spanner on the torx nut that when turned with some force to the left released the tension on the strut and thereby the belt. I did have to then release it again to thread the belt around the various pulleys but attaching the spanner once more and gently applying pressure the strut compressed and I was able to slide on the belt. Many thanks. Barry