EDIT: I got it out. I had JUST enough room for another hole, I knew I was only gonna have one more chance at drilling for extraction so i had to spend a lot of time with the hammer and pick making a spot for the drill bit to set in that it wouldn't slip off at all, the same thing happened with the 2nd hole to where the extractor bit lost it's grip and stripped the hole too much. This was my first time ever extracting broken bolts, but when the extractor lost it's grip i realized you can just drill into the same hole deeper and then the extractor can do it's job again, actually had to repeat this twice because the extractor kept stripping the hole

Over torqued 2 valve cover bolts, bought an extracting kit. removed the first successfully with a 5/64 bit and it's matching left hand threaded extractor. On the second however, the surface I was drilling into was slanted, and if I tried making my pinhole to drill into it always wanted to shift to lower ground, I thought even though I would be a little off center I still had enough room to work with. Drilled it, switched to the extractor and it came part of the way out before the extractor seemed to lose it's grip and it spins in place.

(RTV I had handy to hold paper towel so metal shavings weren't going in my engine)

now I don't think I have rough room to drill another hole, the bit likes to guide itself back into the same hole and I'm afraid of stepping up to a bigger 1/8 bit and extractor

I have some 2part epoxy and jbweld, if it would be strong enough to somehow glue something to it and twist the bolt out, these don't get torqued very tight 20inch pounds, and ive already taken it out part of the way

 

I see the off center drill hole.

I would put the edge of a small flat head screwdriver in the hole, then tap that with a small hammer. Counter clockwise of course. It might unscrew enough eventually that you could grab it with a needle nose plier or vice grip.

 

yeah it's on of the back bolts along the firewall kind of a pain in the *** to get my drill back there. I tried the flat head and didn't seem to get any movement out of it

 

The only thing with the epoxy is that you would have to use a smaller bolt in place of the broken one if you stop there.

Use enough epoxy to cover the now drilled surface broken bolt. Once set, redrill into epoxy and broken head.

Also, stuff them chambers with cloth, and fully tape over them ports with tape. Your surgery has intensified.

Pack lots of patience ..... am watching!!

 

Bummer... I've never had much luck with any easy out set. I will soak it in liquid wrench for a while (hoping to make extraction easier) and drill a small pilot hole. Then, pound a hex key into it and try to turn the hex key. Mixed success... I am not the bolt removing master. That's a quick way to put my project on hold indefinitely