The good news is it is possible to remove the cylinder head from a W638 Vito with the engine in the vehicle. I couldn't find this info anywhere before I started so I hope it's of use. Thinking about putting this back together, can anyone confirm that the chain tensioner need to be removed and reset before the chain is put back into service? Obviously all tension has gone from the chain and it is just hanging there until I put all the sprockets etc. back. I don't want to stress components if the tensioner has tightened up fully, but equally am wary of winding it all the way back in in case the chain is then too loose. How do I set this up please? Cheers PS The HG had blown. It was letting coolant into cylinder no.2, having corroded between the cylinder and the water jacket on the exhaust side.