I have a question.  After some struggling, we finally got the water jacket drain plug out of the block.  However, the passage is completely blocked by crud and no water drains out.  I have tried to get a wire or coat hanger, etc. in through the hole to clear it out, but the passage makes such an abrupt right angle turn that I haven't had any success so far in clearing it.  I wasn't surprised to find it blocked because I've read on the forum of others who have encountered the same problem.