The tensioner itself is fitted to the water pump housing. They are around the £80 mark from Fords as they only come as a complete water pump assembly.

If I had seen this yesterday I may have been able to help as I think I have a complete pump sat in the garage from one of the 200's that I have stripped.

As Fiddy has said change the pump whilst you are at it. I am home on Friday so can help you do it then if you want me to. Do not drive the car without the waterpump thpough as it will kill the lump straight away without showing any of the usual signs of headgasket failure though.

Give me a call on 07590 578729 if you need any help. Sorry but am back in Amsterdam so cant help more at present.

Jeff