Removing broken off bolts from cast iron block

[tysonh]

Well two of the 9 head bolts broke off in the block on a Kohler K321 block.

This had sat outside in the weather for years before I recently bought this log splitter. I got the aluminum head off, one of the bolts is flush to the block, the otheris about 1/4" proud of the block. I tried to mig weld a bolt to him and turn it out with no luck. The head bolts are Grade 8, can you not weld to grade 8 ?? The other I tried the a little heat with no luck. I've tried heat, penitrating oil, and I don't think I want to risk drilling myself as the engine is in good shape mechanically. I've heard some say you can just torch them out of a cast iron block with no damage to the cast

I think I may just call a machine shop and see how much they would want to do the job. Does anyone have any other ideas to try ?

https://scontent-lax3-2.**.fbcdn.net/v/t1.0-9/21105460_10212578472552072_7722949640456092668_n.jpg?oh=5d644413070da9baf0aa16d0679c5c4d&oe=5A211E97

https://scontent-lax3-2.**.fbcdn.net/v/t1.0-9/21077675_10212578481032284_5447224293144187816_n.jpg?oh=67790dc12cbdedf00beaa1d3531913a8&oe=5A1FC92A

 

[plinker]

Carefully center punching the broke off piece and drilling can work, I like to use transfer punches for this. Start small and go larger until you can pick the bits out of the threads (or an extractor takes effect).

I prefer to weld a nut to the broke off piece if at all possible. as long as it about flush or above it usually works. Use a coarse threaded nut and if there is room put a flat washer down first. Basically plug weld the nut full and let it cool a bit. I've had mixed results with trying to turn it out red hot, either works or it doesn't. It may take several attempts. The hotter the temp on the welder the better, the nut may melt some but that is ok. Grade 8 hardware is easily weldable, I do it often at work.

 

[Jazz1]

^ just like that. It's tedious but it works. Removed 2 in similar situation couple weeks ago

 

[tmcquinn]

I have a machine shop nearby that specializes in removing broken bolts. I watched them once after my son broke some bolts off flush in a block. This, of course, wasn't bad enough, I then broke an extractor off in one of them (never again). Anyway, the guy took a die grinder and carefully cut away the extractor and bolt until there was so little left that he backed the remains out with a pick. The downside is that he said the die grinder was $600 and it looked to me like you probably needed to do it several times a day to even approach his skill level. But I know now that no matter how badly I screw up my own attempts at broken bolt extraction there is someone who will undo the damage for $25.

 

[sberry]

If it needs more twist power I weld a lock washer on first, it makes a stronger weld when using common filler wire. I tossed some a while back I should have taken pics of. I should have thrown all the ones over the years in a coffee can. We had over 100 set screws on a machine reman we took out.

 

[SlappyWhite]

Another vote for welding a nut onto the broken bolt.

Gives you something to grab onto, it also puts a lot of heat into the bolt which also helps.

Prior to welding the nut, you can also give them a good soak in penetrating oil--but clean the top off before welding.

 

[matt_i]

I think the machine shop is your best bet, alternatively if you know someone with a Bridgeport or knockoff mill, then that person could potentially do the job if they are experienced.

The advantage of a rigid spindle that can be squared to the work, a (solid carbide spot drill) drill bit that won't walk, and the micro-adjustment of the axes to find center is the best way to get started.

 

[cmandp]

Turn the wire feed down. Too much wire speed and the weld does not penetrate the bolt enough to make a strong weld to it.

Drill it only as a last resort.

 

[MoonRise]

Weld a nut onto the stud/bolt end.

Sometimes it takes more than one attempt.

The nut is so that you have something to grab onto. The welding is so that you can attach the nut to the end of the bolt/stud.

But more importantly (when dealing with a 'stuck' fastener) is that the intense heat of the welding helps to expand (and thus tends to 'loosen' the stuck threads) the stud/bolt. Let it cool (so that the metal contracts/shrinks, and so that you don't burn yourself ) and try to remove the nut-n-stud/bolt. If your weld wasn't 'good', the nut will probably twist right off of the end of the stud/bolt. Take a deep breath and weld another nut onto the end of the stud/bolt remains. Repeat until you succeed with removing the stuck and broken stud/bolt.

Intense heat means get the stud/bolt up to red-hot. An air-propane torch does NOT (generally) produce the heat needed for this type of job. Oxy-fuel is usually needed.

For a 'critical' item, you really can't/shouldn't weld onto a fastener.

For removing a broken/stuck stud/bolt, weld a nut onto the end and remove the broken/stuck piece. You're just going to remove it and throw that item away (or put it into a coffee can as a 'trophy', showing that you won against the stuck metal piece. ).

It may take more than one attempt. Keep at it. I think someone here at GJ posted once that their 'record' for how many weld-the-nut-to-remove-the-stud/bolt was either in the high single-digits or just into the teens until they had success. My personal 'record' was somewhere in the mid single-digits IIRC until I got the ****** out.

re: "torch it out" Someone who is pretty good with an oxy-fuel cutting torch can often 'burn out' the steel stud/bolt right out of a cast iron block. I know of one or two guys who can do so. Me? I weld a nut onto the ******.

 

[dr_clyde]

This is a common customer request for my shop. I get all kinds of broken off bolts, taps, drills broken into the widest variety of stuff. Manifolds, heads, machinery, you name it. I've used this method on brake rotor screws when the head strips, that kind of thing. Sometimes I need to pack the welder and remove the broken bolt still in the machine. A local car dealership deals in classic restorations and exotics, and their mechanics are always bringing me rare or one of a kind, unobtanium manifolds and heads that have some studs broke off in them.

I took some photos of a dead simple job to illustrate my technique. This is just a tap broken off in a steel plate. I just took it out because it was faster than re-cutting stock, drilling new holes and re-tapping. Plus the plate was already welded into a fixture.

I use the TIG welder for these jobs. I have never liked using a nut or the mig welder. Too much hassle to get a nut and try to hold it in place while getting the weld. The TIG lets you heat up the offending bolt or tap without adding any filler. Seems to be more effective in my experience.


The broken tap in question.

Butter it up with a little 309 SS rod. I use this when removing things made of tool steel. Makes for a little more forgiving weld than just steel filler. 309 is designed for dis-similar base metal welds.

Weld on some sort of lever. I usually use some CRS rod, but I've been known to use a bolt, or on smaller stuff just a length of 1/8" tig filler.

I give it a squirt of penetrating oil. Usually Kroil, but WD, liquid wrench, PB, anything will work.

Wiggle it back and forth a little. Let the oil get down in the threads if you can. Gently work it back and forth, letting the oil do its thing. As the stud cools, it will open up a little space in the threads.

Then, just back the thing out. It sometimes takes a few applications. Smallest I ever got out were some #4-40 screws in my buddy's radial arm saw overarm that broke off.

I've also used a pin punch and a hammer to work a stuck stud around. A small carbide end mill in the Bridgeport works wonders on broken drills and taps. Some things need a little hole in them to make a relief for the threads to collapse into.

Last ditch effort is a hand drill and extractor. These usually make things worse. Hard to drill straight on a good day, and these jobs are rarely a good day. I usually will buy a new part before using one of these, if I can. Almost always cheaper to just start fresh at that point.

 

[dr_clyde]

Where are you located?

 

[jonhdw]

Yeah drill out and chase the threads with a tap is my go to method.

 

[AngryBeaver]

This is a common customer request for my shop. I get all kinds of broken off bolts, taps, drills broken into the widest variety of stuff. Manifolds, heads, machinery, you name it. I've used this method on brake rotor screws when the head strips, that kind of thing. Sometimes I need to pack the welder and remove the broken bolt still in the machine. A local car dealership deals in classic restorations and exotics, and their mechanics are always bringing me rare or one of a kind, unobtanium manifolds and heads that have some studs broke off in them.

I took some photos of a dead simple job to illustrate my technique. This is just a tap broken off in a steel plate. I just took it out because it was faster than re-cutting stock, drilling new holes and re-tapping. Plus the plate was already welded into a fixture.

I use the TIG welder for these jobs. I have never liked using a nut or the mig welder. Too much hassle to get a nut and try to hold it in place while getting the weld. The TIG lets you heat up the offending bolt or tap without adding any filler. Seems to be more effective in my experience.


The broken tap in question.

Butter it up with a little 309 SS rod. I use this when removing things made of tool steel. Makes for a little more forgiving weld than just steel filler. 309 is designed for dis-similar base metal welds.

Weld on some sort of lever. I usually use some CRS rod, but I've been known to use a bolt, or on smaller stuff just a length of 1/8" tig filler.

I give it a squirt of penetrating oil. Usually Kroil, but WD, liquid wrench, PB, anything will work.

Wiggle it back and forth a little. Let the oil get down in the threads if you can. Gently work it back and forth, letting the oil do its thing. As the stud cools, it will open up a little space in the threads.

Then, just back the thing out. It sometimes takes a few applications. Smallest I ever got out were some #4-40 screws in my buddy's radial arm saw overarm that broke off.

I've also used a pin punch and a hammer to work a stuck stud around. A small carbide end mill in the Bridgeport works wonders on broken drills and taps. Some things need a little hole in them to make a relief for the threads to collapse into.

Last ditch effort is a hand drill and extractor. These usually make things worse. Hard to drill straight on a good day, and these jobs are rarely a good day. I usually will buy a new part before using one of these, if I can. Almost always cheaper to just start fresh at that point.

312 is also excellent for dissimilar metals due to the chromium content. also makes great cast iron filler fyi.



normally if I have to weld a busted bolt i use the mig.. High heat, let it cool. most times it spins right out by hand once cool. the intense heat frees the corrosion and or rust.

if I have to drill a stud/bolt, I'll use a torch to heat it cherry red to take the temper out of it. drill after it cools

 

[kbs2244]

I have gone the weld a nut to it with candle wax into the threads while hot route.
It worked.
But, in todays world, I would look into the HF Predator engine replacement route.
You get a new engine for the same money.

 

[Dagny]

It's not magic cast won't blow. I remember being afraid to try it. Take the cutting torch heat the bolt straight on and blow it then heat again and blow it till the whole bolt is gone. I remember the first time I did it was a Ford 7700 tractor AC compressor mount.

 

[rnscustom]

Weld the nut or washer but don't try to be neat , puddle the $hit out of it and get it hot as you can , use grade 8 nuts or washers , grab the puddle with vicegrips .

 

[rnscustom]

Let it cool down