Read some of the similar topics on here already. Bought a 2.2 vectra with suspected timing chain brakage. ordered timing chains, gaskets etc. Carried out work, car ran like a dream, though noticed if i booted it, i left rather a large cloud of smoke behind me. Took no notice as i drive pretty steady. after a couple of months engine started knocking really bad. Inspected work i'd carried out and everything seems fine. Did notice top of engine seems dry. I suspect after reading forums on here that it is this oil regulator. Wondered if this was blocked, if this would also cause the excessive smoke when i boot car???? Cams seem a little scored, but ive seen worse. Tappets dry also. Is this oil regulator situated in the middle of the block at back between two cylinders. Havent stripped it down again yet but not sure what i'm looking for. Cheers. Mick