Extracting broken bolt

[JakeVII]

I went to change my thermostat (91 FJ80) and broke the rear left bolt on the housing. I think about half an inch of the bolt is still down there.

I've extracted broken bolts before, but never on an engine/ installed auto part.

How would you go about getting that broken bolt out?

 

[bajaphile]

I've had good luck with left handed drill bits. Work slowly and carefully. Start with a small pilot hole down the center of the broken bolt. Then work up... Left handed bits will bite in and sometimes just pull it out. Otherwise you can drill with a regular bit and then use an extracting bit or jam in an old screwdriver in the hole and reverse it out.

The main thing is to work slow and don't damage the internal threads.

 

[JakeVII]

Nice, that sounds nifty. I'll give it a shot!

 

[jjgarci1]

Is any part of the bolt sticking out of the block? You can try to weld a nut to it...

Weld the inside of the nut to the bolt, using a floret/plug weld technique.

Sometimes the heat produced by welding on a nut can be just what is needed to help loosen the bolt.

 

[Noahrob]

Ive used both methods and it depends on how it broke. I really like the drill and left handed thread extraction tool as often times bolts brake flush, or at least they do at my house...

 

[Pin_Head]

Don't use an EZ out or any other extractor on a rusted bolt. Welding a nut on works great, but it it tricky if the bolt snapped a half inch down in the hole. Try the left hand drill first. Try heat too.

 

[fjc-man]

If all attempts go badly.... there's "timesert" for a good repair.

 

[JakeVII]

Thanks for the advice fellers!

I hadn't actually heard of left hand bits for this before today, but that's just my own lack of experience.

Timeserts looks like they'll save me if I mess up. Never woulda found those on my own.

I need to get a welder, too...

 

[rusty_tlc]

My method.
First attack is always to soak with penetrating oil then go have a beer and cone back the next day.
Second wave; grind any exposed surface flat using a dremel or die grinder, using a sharp punch held at an angle and a small ball pean hammer try to tap the screw/bolt out.
If the second wave initially fails apply heat to the surrounding metal and try again.
Third wave; if the above fails use the dremel/die grinder to create a divot in the center of the screw/bolt. Drill a small hole down the center of the offending hardware, a regular drill works fine for this and is much more likely to be in your shop that the left hand variety. Repeat the penetrating oil application, heat, punch steps.
Fourth wave; repeat the drilling process with the next size up drill bit.
Repeat as required, at some point you will either succeed, remove enough of the fastener to clean up the threads with a tap, or destroy the threads in the hole.

 

[mudgudgeon]

Thanks for the advice fellers!

I hadn't actually heard of left hand bits for this before today, but that's just my own lack of experience.

Timeserts looks like they'll save me if I mess up. Never woulda found those on my own.

I need to get a welder, too...

see breaking a bolt is a good thing! Now you get to add a whole bunch of tools to the collection



rusty is onto it!

 

[Pascoscout]

I use these:
The QuikCenter Tool

Drill the pilot hole with the supplied drill bit then either switch to left handed drills if the bolt is not too frozen in or just keep stepping up in size till you get just under the threads. Run a cleaner tap in and you're done. Repaired my shock mount bolts this way when they broke off and also done many an exhaust manifold bolt with the manifold still in place.

When you buy drills get cobalt. Regular drills won't cut the bolts and carbide are brittle and break pretty easy.

 

[Michael Hanson]

Hi, pb Blaster ,soak ,heat, give it time to work . Repeat then , cobalt left hand drill bit and work slowly and keep bit cool with oil while drilling . Mike

 

[scrowley]

If welding doesn't work you can try to center punch it, then drill bits starting small and work way up to almost whole bolt. Then you reverse bit. Lots of lube.

 

[TR8TR]

Broke my first bolts yesterday on my very first repair - this info is really helpful. Thx

 

[bloc]

After drilling out then breaking an extractor off in the broken bolt, then getting it ALL out easily with a welder, I'll be skipping straight to the mig from now on. Personally.