My friends tractor had badly contaminated milky oil so we took the head off and the gasket and head appear to be ok. However the block definately has two cracks in it. Do we need a new block and how else would the oil be getting contaminated. Thanks
The usual way for the water to get to the oil is that the lower O- ring for the cylinder sleeves let the water through. This crack is not so bad that it looks. I have no other experiance of an engine with a crack like that than I once sold an engine with a crack to a guy, and he bought it because it was smaller than the crack in his old engine.
It could very well be the crack where it's leaking. Also if you live in a cold country, just don't bother with water, use anti freeze ! It stops the block corroding inside also.