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Broken Bolts in engine block

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Hi,

when I tried to remove the thermostat housing and waterpump from my 37 Special engine, unfortunately two bolts were so blocked that they broke off. Now ca. 1/2 inch of the bolts is still sticking out of the motor block housing. As the engine is still built in, there is not much space to tinker between the rad and the engine. Question:

Does anyone know any magic how to losen them and get them out? They seem to be corroded inside the thread as if baked together.

Is there any fluid (besides the usual MOS2), that kreeps in and dissolves the rust?

Has anybody made good experience to just weld a nut to the remainder and try to turn it out?

Thanks for your advice.

Christian

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Christian, Welding a nut to the remaining bolt and attempting to turn it out may be worth a try. For one thing, application of the heat of welding may break the rust bond.

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About the best rust penetration fluid on the market right now (in my opinion) is "Kroil" by Aero Corporation. It might be good to soak it for a few days and try a vise grip on the stub sticking out but don't twist it off as this will still give you something to weld a nut on. Others have had success by warming enough to melt paraffin on the stub and let it work down the threads. Yet some others swear by a mixture of ATF and acetone. I also have a 37 Special and you are so right about it being CLOSE work around the front of the engine.

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A 50-50 mix of automatic transmission fluid and lacquer thinner or acetone might help loosen the threads. I have a `41 Buick 248 engine I rebuilt recently that had the same water pump bolts twisted off. Two of them had about a half inch sticking out, I heated them up with a torch, smacked it with a hammer a couple times and got on them with a set of vice gripes and they screwed out. I think the heat really helps. I used anti seize thread compound on all the bolt threads when reassembled. Of coarse my engine was out of the car and easy to get to. Good luck, Tom

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Christian,

AzBob is on the right track, but you must let it cool completely to reduce expansion from the heat before trying to remove it. I would try the 50/50 ATF & Acetone mix first for a day or so before welding. IMO, all penetrating oils use a carrier solvent to deliver light oil to crevices where it helps to reduce torque. Acetone is an excellent carrier as it evaporates quickly. But it also separates from the oil and that probably why it is not used in commercial products. You just have to shake it up well before use. See below:

Machinist's Workshop magazine published some information on various penetrating oils.

The magazine reports they tested penetrates for break out torque on rusted nuts.

They arranged a subjective test of all the popular penetrates with the control being the torque required to remove the nut from a

"scientifically rusted" environment.

*Penetrating oils ........... Average torque load to loosen*

No Oil used ................... 516 pounds

WD-40 ..................... ... 238 pounds

PB Blaster .................... 214 pounds

Liquid Wrench ...............127 pounds

Kano Kroil .................... 106 pounds

ATF*-Acetone mix............53 pounds

The ATF-Acetone mix is a "home brew" mix of 50 - 50 automatic transmission fluid and acetone.

Note this "home brew" released bolts better than any commercial product in this one particular test.

Our local machinist group mixed up a batch and we all now use it with equally good results.

Note also that "Liquid Wrench" is almost as good as "Kroil" for about 20% of the price.

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You are lucky that you have part of the bolt sticking out.This is how I have removed many broken bolts in the past. I would first very firmly tap on the stub sticking out several times. Then heat with an acetylene torch on medium flame , all around the bolt. Try not to heat bolt itself, but the material around it. Bring the metal around it to a glow. I then quench by pouring cold water with a steady stream to completely cool all parts. Soak bolt with penetrating lubricant. Using vise grips , very lighty attempt to turn the broken bolt back and forth. DO NOT break it off, you can always tap on, reheat and quench again . If movement is detected soak it with lube again and keep going back and forth. Always use minimal force. Finesse, not force. The tapping with a hammer and the quenching has worked for years for me . Good luck.

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Christian,

AzBob is on the right track, but you must let it cool completely to reduce expansion from the heat before trying to remove it. I would try the 50/50 ATF & Acetone mix first for a day or so before welding. IMO, all penetrating oils use a carrier solvent to deliver light oil to crevices where it helps to reduce torque. Acetone is an excellent carrier as it evaporates quickly. But it also separates from the oil and that probably why it is not used in commercial products. You just have to shake it up well before use. See below:

Machinist's Workshop magazine published some information on various penetrating oils.

The magazine reports they tested penetrates for break out torque on rusted nuts.

They arranged a subjective test of all the popular penetrates with the control being the torque required to remove the nut from a

"scientifically rusted" environment.

*Penetrating oils ........... Average torque load to loosen*

No Oil used ................... 516 pounds

WD-40 ..................... ... 238 pounds

PB Blaster .................... 214 pounds

Liquid Wrench ...............127 pounds

Kano Kroil .................... 106 pounds

ATF*-Acetone mix............53 pounds

The ATF-Acetone mix is a "home brew" mix of 50 - 50 automatic transmission fluid and acetone.

Note this "home brew" released bolts better than any commercial product in this one particular test.

Our local machinist group mixed up a batch and we all now use it with equally good results.

Note also that "Liquid Wrench" is almost as good as "Kroil" for about 20% of the price.

Don't you have to be super careful with acetone/atf mix around paintwork?

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You are lucky that you have part of the bolt sticking out.This is how I have removed many broken bolts in the past. I would first very firmly tap on the stub sticking out several times. Then heat with an acetylene torch on medium flame , all around the bolt. Try not to heat bolt itself, but the material around it. Bring the metal around it to a glow. I then quench by pouring cold water with a steady stream to completely cool all parts. Soak bolt with penetrating lubricant. Using vise grips , very lighty attempt to turn the broken bolt back and forth. DO NOT break it off, you can always tap on, reheat and quench again . If movement is detected soak it with lube again and keep going back and forth. Always use minimal force. Finesse, not force. The tapping with a hammer and the quenching has worked for years for me . Goodluck.

Wow! You are begging to crack the cast iron of the block using that technique, especially quenching with cold water. Just the thought of that cold water hitting that cast iron causes my butt to clench.

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A combination of heat, WD-40, and vise grips almost always work for me. Let the WD-40 soak for a couple of days. Don't be afraid to try to tighten it more in an attempt to wiggle it. In the rare cases that does not work, cut it off flush and drill it out.

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Yes, Acetone will remove paint. But with a mix of light oil, it will also help remove a stuck bolt.

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Wow! You are begging to crack the cast iron of the block using that technique, especially quenching with cold water. Just the thought of that cold water hitting that cast iron causes my butt to clench.

I know that this technique seems harsh, I have probably removed 50+ broken bolts and studs in various states of decay using this method. I have performed it on cast iron, cast steel and cast aluminum parts. On aluminum do not heat until glowing. Only mild heat .

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Ah... the endless quest to safely and completely remove rusted fasteners. After my 1937 Special sedan came back from a shop doing a "driver restoration". Promised to be ready to be able to drive to the Buick Nationals 2012 in Concord North Carolina. Well it was finally returned to me in Sept 2012 with the comment that they had done all the heavy lifting and I just needed to do some"tweeking". After nearly 9 months of "tweeking" and re-doing much and finding things overlooked. I thought I would check the operation of the thermostat and found that one bolt was snapped off and just glued in with Blue RTV. From the photos I took of the ordeal it simply infuriated me knowing that they had the front nose off to have the Radiator redone?? Not easy to notice with the radiator and hood in place. I don't believe they snapped off the bolt (could have been there before I bought the car in 1987), but simply ignored it. I assure you the drilling out /re-tapping job would have been tremendously easier without the radiator and hood. Just one of many little ordeals which needed to straightened out on what was promised.

post-79073-143142984851_thumb.jpgRe-tapping in really tight quarters.

post-79073-143142984825_thumb.jpg

post-79073-143142984835_thumb.jpg

post-79073-143142984841_thumb.jpg

post-79073-143142984846_thumb.jpg

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Restorer32 is right. The purpose of heating the metal is to get it to expand and put some pressure on the rust to break its bond. Once you get above 850F (450C) the expansion of most carbon steels is virtually a flat-line so adding any extra heat after that doesn't help the process. If you heat 'till it glows you're actually up around 1200F (650C) while 850 is just above where it turns blue.

Without a doubt raydurr will have hardened the the surface with his quench process but I think why it is still a success is the hardening has been limited to just the surface but it does run the risk of initiating cracks at the surface (which may not be visible to the naked eye at the time you do it). Don't get me wrong I'm an advocate for using heat but you don't need to heat it to a glow and you shouldn't be quenching unless you're planning on tempering after, which is a whole different ball of wax.

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Christian, Welding a nut to the remaining bolt and attempting to turn it out may be worth a try. For one thing, application of the heat of welding may break the rust bond.

I would fix it tthe same way..

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A combination of heat, WD-40, and vise grips almost always work for me. Let the WD-40 soak for a couple of days. Don't be afraid to try to tighten it more in an attempt to wiggle it. In the rare cases that does not work, cut it off flush and drill it out.
. If you're at the point where you have to drill out a broken bolt, I've used " left hand drill bits", or drill bits that work in a reverse or counter-clockwise direction with the use of a reversing drill motor, with a keyed chuck. The advantage to this is that many times the broken bolt will unscrew as it is being drilled.

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Left hand drills , i think you mean this :post-81846-143142988501_thumb.png

are very dangerous, because of strutting the bolt against the rusty thread.,then its impossible to wrench it out without break off the tool.

If this happen , its starts a lot of fun.

I would use this tools ONLY if i know the bolt is not very tight nside the hole.

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There are drills that work the opposite direction of most drills. They are called left hand drills or "reverse flute drills." What is shown above is commonly referred as an easy out.

Here is a link to the reverse flute drills from Harbor Freight.

http://www.harborfreight.com/13-piece-left-hand-drill-bit-set-95146.html

They are also available from McMaster-Carr.

Edited by Larry Schramm (see edit history)

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I just use a tiny bit and slowly work to larger until I can weasel it out with some needle nose and/or a small chisel.

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Hi,

My weapon of choice is left-hand drills. They are not extractors, which jam and break, but drills which don't. Harbor freight, McMaster-Carr, even Sears have them.

--Tom

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I see lots of ideas here, but nobody has mentioned STEP #1.

PULL THE RADIATOR FIRST !

This give you much more room to work, and lessens the chance of damage to it.

Mike in Snowy Colorado

PS; When I had to get EVERY BROKEN manifold bold out of my GMC motorhome, (while laying in the gutter in front of my old house) I heated the bolts red hot and soaked them in "Liquid Wrench" for a day. A couple took 2+ times of this.

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Harbor Freight sells nothing but inferior crap, not worth buying/bringing home. I can`t believe all that China crap is even allowed to be imported into this country. USA sure isn`t what it used to be..

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Harbor Freight has a lot of good inferior crap, and a lot of bad inferior crap. My $55 wet saw has lasted several jobs. Their welding wire and cutoff discs are also good. I probably wouldn't buy any drill bits there.

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Friends,

thanks a lot for all the interesting input. Since I was lucky enough that 1/2 inch of the bolts were sticking out, I opted for the simplest solution. I welded a nut on the remainder and started to turn it slowly with a wrench. Twice the nuts broke off at the welding spot, but then I increased the current with minimal wire progression and gave it a 3 second blitz, which almost molt down the nut. Both bolts came off this way. No idea if soaking in an Aceton/ATF mix helped or if it was just heat combined with subtle-brute force.

It´s great to have such a broad base of knowledge and wisdom here!

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