Cracked engine block

I would check with a air hose and some soapy water to see if it is a crack or a casting flaw.Was there a problem before with the block putting water into the oil?If you used a carbide cutter to grind it and see if the crack is deep into the wall casting,you can see from their.cast iron can be welded and repaired if its not in a vital area.Post of a picture could help us even more to help you.Mrmopartech