Broke my water pump bolt. Now what? (Update - broken bolt is out)

cruiser said
Still working the problem. Heated it up again, more PB Blaster, cooled it, tried to turn with a vise grips. No luck - wouldn't budge. Have totally buggered up the threads on the shaft. Before doing this, tried to fit an extraction tool on the protruding part. Not enough length to make the connection. Next step - drilling it for a bolt extractor tool. Going out to buy left hand drill bits.
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Don't bother with left hand bits. They will unscrew themselves only if the bolt is loose. I wouldn't even drill a hole for a extractor at this point. Welding on a nut is the best way. If that doesn't work, remove the head and have the machine shop drill and retap. Trust me, I have seen this scenario before.