Which one do you have Andy? Is it the one that you put an allen key in to adjust, the one that has a swing needle that needs to be adjusted to line up with the marks on its baking plate?
If so you should have a little arm with a bent over end to it. This locates into a recess (can't remember exactly) in the block. This means that the tensioner is pretty much solid. Tighten up the large bolt in the centre leaving it loose enough to adjust the swing arm by putting an allen key in the hole of the inside arm then tighten the middle bolt to the specified torque.
Right thats what i thought but it doesn't matter what i do with the tension part (Allen key adjustment thing) when i tighten up the bolt it just goes all the way to the left. Is that right or is my tensioner buggered?
Laney, when you say all the way to the left do you mean the adjuster (bit the allen key goes in) or the indicator ?
The indicator won't look right till you've manually turned the engine a couple of turns. If you mean the bit you put the allen key in you need to keep it in place with the allen key while you tighten the bolt. My tension adjusting bit sits at about 4 o'clock if that helps. If you've had the wheel off then as Savage says make sure the bit on the wheels backplate is snugly in the recess that holds it still and prevents it turning with the bolt as it's tightened.