Broken bolt inside block : removal question.

I have a tap and die set, I could drill out the entire bolt hole, with the rest of the bolt and retap the larger hole, but I was wondering if anyone knows if the casting around that area is thick enough to accommodate such a operation, and I do t want a whole bunch of metal shavings to be spewed into the crank case if that bolt hole is open ended into the crank case.

The remaining piece of broken off bolt only allows about 4 threads of a bolt to be threaded into the block untill the bolt bottoms out against the broken off bolt. Would using a small bolt and appropriate amount of loctite work to hold the bolt and pump o the block during it's operation?

If you are concern about the drill staying on center due to a rough surface at the break you might be able to get a Dremel in there and either flatten it, or create a low spot at the center so the drill doesn't walk. Even if you bugger up a thread or two the internal thread will still have grip at the root.

Also, if the clearance allows to slide the pump on/off you might try using a stud (probably need all-thread in this case) and see if the 4 threads are strong enough to hold. But at least this way the nut can be threaded down all the way and any rotational wear is on the stud, not the threads in the block.

Hi wittsend, the stud idea is Intersting, but I think I'm past that now.... Or maybe not... If I need to drill it out and retap the hole I could use a stud....

Hi hemirambler, the block idea sounds good to guide the drill, but I also think I may be past that idea now, as this morning I tried to drill out a portion of the high edge of the broken off bolt while holding the drill against it and slowly carefully drilling and carving away at it and use a diff set of bolt extractor, but after several attempts I think I've exhausted it's opportunity to be effective, there just wasn't enough of a piece of bolt left for that method o work, and now at this point I've found that out, bit it also has made the other ideas of guiding the drill bit, or shielding it with a piece of pop can ineffective, I think it might be too late for those ideas as what I kept hoping would work didn't and now I think I've started to drill past the bottom of the bolt hole and into the block...

I think I'll have to drill it out and retap the hole.
 Also, I'd like to ask, since I'm not devastated by what's happened, if I should be? What would be so wrong with having to drill out and retap? Is it not possible for some reason?