Broken Bolt Extraction?

UTfball68

UTfball68

Well-Known Member
Joined
Jul 18, 2008
Location
Granite Quarry
Hey fellas...I was putting a new thermostat in my 79 Bronco, get to the last bolt to button her up, and about half way in, the bolt snaps off flush with the block. All I had here at school were basic hand tools, so I couldn't do anything with it. I limped to a radiator shop about a 1/2 mile away and they said they could get it out for me. They couldn't...I don't think they had the right drill bits...Anyway, my dad is sending up some left rotation carbide bits and some easy outs and a GrabIt set. I think I should be able to get the bolt out with this set up. So the point to this thread is...you guys got any tips, pointers, drill/bit set up that will make the extraction any easier?


If you guys have anything to add I'd really appreciate it...or near Knoxville, TN and wanna swing by to help and throw back a couple beers...lemme know. Thanks.
 
I usually just use standard high quality (non carbide) drill bits instead of LH bits. I've used the Craftsman easy-outs and they have worked very well for me. Take your time and you'll be fine.
 
Pre-soak with wd-40 (or something similar)Try the best you can to mark center. Drill first hole with 1/8 drill bit then slowly go up to the size you need for easy out. If it doesn`t want to budge don`t force it. I usually "rock" it back and forth a few times till it starts to move. Take your time with it.
 
Alright thanks for the input fellas...I'm no rookie to tools, but believe it or not, through engine builds and truck restores...this is the FIRST bolt extraction I've ever had to do. So I'm a little nervous...but it's nothing I can't handle.
 
If you have a good set of lh drill bits it will help. The key as stated above is to try to get it centered. Sometimes the lh drill bits will back the bolt out on the 2nd or third size increase.
 
Ive never had any success withe easy outs or similar. Ive only ended up with a hardened piece broke off on problem bolt.

9/10 times I end up welding a smaller dia. bolt to the broke off one and backing it out that way. The other time heat works.
 
If you can't weld another bolt on.....

Center drills work better than brill bits.. Drill bits tend to expand the bolt into the "body" more. I believe Craftsman makes a set. They call them screw extractors, but they're left handed center drills.

Soak it overnight with a penetrating fluid - PB Blaster, KnockERLoose, tap it with a hammer in several directions afterwards if you can.

If you can..... sometimes heating it up until it gets a little red will "pop" it loose. This may not work for you considering where it's at and you have no head.

If it's not leaking, foek it.
 
Thanks for the replies fellas...I appreciate all the input.


rbo...it's leaking like a banshee...the bolt didn't break off and stay in the tstat housing...it broke off flush with the block, so the one side of the housing isn't clamped down at all. I lost about a gallon of coolant in a half mile.
 
I like to try to grind a slot in the shank of the bolt first, then use a flathead screwdriver to back it out. Heat the bolt and rub it with a paraffin candle first. This will wick the wax into the threads, loosening the corrosion that's binding the bolt. Be careful to gouge the surrounding block as little as possible. A Dremel with a cut-off wheel works best for this. If that don't get it, then a chisel or good punch and a hammer might work. Set the chisel near the edge of the slot and try to back it out by hitting it with the hammer, tapping it counter-clockwise. If that fails, I usually weld a nut on the end of the bolt. I don't like welding bolt to bolt, because of the lack of weld area. If you build the weld up inside the nut you set on top, you're basically making another head on the bolt. Plus, the heat helps loosen the bonds of time, too. When I'm at work, and the TIG welder's handy, this is usually my first approach. When I'm at home, it's the slot and/or chisel. I rarely drill bolts out, as I sometimes end up getting off the center and drilling into the threaded hole a little. It's worth a shot, though. I have bought some left-handed drill bits to try next time I've got a stubborn one. The one time I tried a Grabbit, it broke easily, and I was using it according to the directions. Not impressed.
 
SkyHiK5 said:
Ive never had any success withe easy outs or similar. Ive only ended up with a hardened piece broke off on problem bolt.
9/10 times I end up welding a smaller dia. bolt to the broke off one and backing it out that way. The other time heat works.
Click to expand...


Yeah, I think the welding a nut or bolt to it is the way to go.

Recently had to use an easy out when an aluminum caliper bolt snapped (stupid subaru!!). First time that I've ever had success with 'em and I think it because I was drilling into aluminum.

Good luck, UT. When they're broke off flush it can be a royal pain.
 
I do industrial HVAC, sometimes we have 5/8s and larger bolts break off. here are a few things i have had luck with

extractors dont buy cheap ones from home depot or lowes, i use PROTO fluted extractors from Grainger, drill it out to the correct size stated on extractor, put extractor in hole and tap it in with a hammer, then gently try to loosen the bolt

if that doesn't work try this

drill the bolt out as much as possible, try to cut a notch into the shell of the bolt with hammer and chisel from inside, then try to collapse the bolt, you may have to run a tap into the hole to clean the treads up but this is how i have taken 1 inch bolts that were rusted into cast iron out
 
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