Hi Simon,

John is right these can be a mare! as he says change the guides and modified tensioner use genuine, one thing make sure the cams are locked at the rear then the variable valvetronic unit at the front is turned back (Inlet one way and Ex the other I think!) otherwise they can cause problems again renew them if they will not lock properly, I had 'fun' with the last one of these rescued from our local BM main dealer after they gave up on it!!

Rob