have taken my cyl. head off to cure a problem where the combustion pressure on boost was leaking into the water jacket on cylinders 2 & 3. the head gasket was damaged in those areas, and i'm not yet sure if the head is warped (will have it checked and skimmed as lightly as possible).

was prepping the block face this afternoon ready for the refit sometime later and found a crack in the block



the crack is on the exhaust side, coming out from the bolt hole between cyl. 1 & 2 and going to the water jacket forwards and backwards.



i assume that this kind of crack can only be caused by tightening the head bolts when there is oil or water in the hole - or is there any other way?

anyway, it's done now. what to do about it? ideally of course, get a new block (and take the opportunity to replace the 205 with a 200). but is it necessary? what will/could happen if i rebuild the engine as is?