This compresses the rust and then it loosens it slightly as it cools.

The weld itself often isn't that strong but by welding the bolt you heat it and expand it within the hole. This is one of the reasons welding a nut on works. If you can't do that, the next best thing prior to drilling and using the extractor is to heat the bolt red hot and let it cool. I personally think left hand drill bits do work if the bolt isn't too rusty or jammed (it is nice when the bit catches and the broken bolt unscrews). It includes the left hand drill bits (tungsten I think) and they can drill almost anything. I use a Snap-On set that I bought years ago (one of those tools worth the cost). Drilling until you can almost see threads and then using a tap to clean out can work, but doing it well takes experience and it may not be practical, if done wrong and the threads are compromised, a helicoil may be needed. If said broke off item is rusty or seized, accurately center punching it and drilling it out may be best bet IME, starting small & going progressively larger. If broke off recessed, a transfer punch can also be used to center punch the piece accurately for drilling. If the piece is exposed a stud remover can work. Left hand bits are usually first though (unless welding a nut can be done, best method for flush & exposed stuff) as I've had them 'catch' and back the broken bit right out (best case). What you dont want to do is break any of these off in the extraction attempt as life gets rather difficult then. Left hand drill bits, Irwin spline extractors, Lisle super outs and Snap-on's SR40K have all done ok for me, which style I use depends on the situation. Think it's just a TBI 350 in there, has an old school air cleaner I want this thing out of my bay and my life, any other tricks, would a little heat be ok, left hand drill bits? welding isn't an option. What's the best extractor set that isn't rediculous in price, that I can have, in hand, monday. The bolts aren't that long and couldn't tread too deep Probably about 3/8ish diameter, bolt head was I think next size up from 7/16? something standard that was little smaller than 15mm, one broke flush and the other is recessed. finally get the new one from ebay (no one makes that shit anymore) and tear it down.Ģ bolts were broken off in the cyl head. Whole alternator and power steering pump bracket is wobbling around can see it's broke off at the bolt ears. So he drives away and the serp belt shreds, was fine when I test drove it. So some crazy old guy who is attached to a rusty high mileage '93 fleetwood caddy had me do brake and suspension work (leaking brake line) that probably cost around what the thing is worth.

Hanson broken bolt extractor