Removing a Frozen Bolt with Heat

[frank1492]

There is a stainless steel bolt (about 3/16 diam) that is threaded into the center of the motor shaft in an old dishwasher that I am repairing. In order to remove the impeller and other parts for replacement, it was necessary to unscrew the bolt. Having no success, I ground the head off, thinking I could then liberally apply penetrating oil and eventually get the bolt out by turning it with a vice-grip. Despite numerous oil applications and twisting to the breaking point, the bolt has refused to unscrew. It is very important that the bolt not break off, as it would be very difficult for me to redrill the hole concentrically. Would it be worth trying to heat the bolt with a propane torch? How should this be done, and what would the risks be? Would there be increased risk of shearing the bolt off after heating (assuming it still won't yield at the threads)? Your advice is appreciated. I will tell you that I do have a backup plan to extend the bolt length with a collar, but this is not optimal as it will require enlarging the center hole on the impeller and other problems. (This of course assumes the current bolt remains unbroken.) Thanks very much. (Don't hesitate to recommend the backup plan if you really feel that it's the best route.) Frank

[Edwin Pawlowski]

At least you learned a lesson

Just heat the heck out of it and then try the vice grips again. Get it as hot as possible and aim the flame right at the bold.

No. Heating is pretty reliable as long as you don't burn anything around it.

[Grandpa Koca]

Just for grins, are you sure its not reverse threaded? Been there, done that.

[MilkyWhy]

go to hardware store and buy an "easy out". I frankly have not had much luck with them. But...you're pretty much down to that.

[Dean Hoffman]

Some cut.

You need to heat the motor shaft instead of the bolt. The idea is to expand the shaft so it will release the bolt. It might help to heat the shaft then dump water on it to cool it rapidly. Reheat it, then try to unscrew the bolt. Propane might not be a hot enough fuel. I'm used to using an acetylene torch for these type problems. There is something called a mapp gas torch that is fairly cheap and would produce a hotter flame than propane.

Dean

[frank1492]

Thanks all for your kind advice. As to the reverse thread, I knew that was a possibility, but I can see threads so know it's RH. Plus I have a new original parts bolt ready to go. As for heating the motor shaft, I know that's the way to go, but the visible part is very short and I feel I would be heating other stuff that I didn't want to, especially to get it hot enough to do any good. Guess I'm just a wimp..:) As for heating the bolt itself (feel comfortable doing that), why wouldn't that do SOME good? I'd reason that the bolt would expand initially and compress the crap (rust from the motor shaft), then after cooling the crap might not cause it to bind as much. Myth or reality? I will mull over everything you've all said. But when all is said and done, looks like I will be putting my old Atlas metal lathe to work! Will keep y'all posted. Thanks again! Frank

[Noozer]

Are you turning it the right way?

[Charlie Bress]

If you can't get heat to the shaft, try holding an ice cube to the head of the bolt. That might give you enough shrinkage. Another approach is to rap the head the head of the bolt sharply with a light hammer to free up any internal crap in the hole. And of course there are various lubricants designed to seep in and loosen tight fittings. And finally as I type this the thought comes to mind that there may be something like Loctite to keep the bolt from backing out. If that is the case heat will loosen it.

Charlie

[Duane Bozarth]

Sounds like a case of stainless galling, perhaps. SS is notorious for that if overtorqued w/o a lube.

Others have suggested I can only support directed heat at the shaft around the bolt shaft, assuming you can get to it. Alternatively, you try putting the whole thing in the deep freeze overnight and see if the differential thermal expansion will help. Applying heat while cold may help, but you'll need more than propane to do any good, I suspect. The cat's meow would have been to use an impact driver while you still had the head, but that's over with now... :(

[PrecisionMachinisT]

Heat with a torch, then spray it liberally with wd 40 while its good and hot--on contraction / cooling, it will draw the vapor into the thread interface.........this should not only break the bond, but also will turn the "crud" into a sort of "grease", thus lubricating the threads.

[Duane Bozarth]

That's a danger, certainly, but if he uses flame w/ small tip, it can normally be done.

Problem is, it's SS and may be too hard...but it is worth a try...

[Mastermech]

I fear that heating the bolt of shaft may ruin the motor as the heat transfers to other parts. I would suggest getting a few left hand drill bits. Yes they do make them. Try to drill the bolt out with them starting with a small bit and increasing to a larger one as you go. Try to start in the center. I have had great luck using a left handed bit. Most times the bit will grab and unscrew the offending bolt for you. In cases when it does not (this is where starting in the center sure helps) I drill to the point where I have a very thin amount of bolt material left and use a punch to bend the bolt inward and pull it out. Running a tap as a final step to clean up the threads. Good Luck JRE

[Stormin Mormon]

I was also going to suggest Mapp. Much hotter than propane.

Also: Heat the shaft, then spray a tiny bit of water on the bolt. Goal being to cool the bolt. Then try loosen with vise grips on the bolt, and channelocks on the shaft.

[Pop]

Not only that, but sometimes trying to "tighten" a stuck bolt like that will also loosen the crud enough to let it break free even if it's not RT. And if it is, well, you find out , usually.

Pop

[Pop]

Never found that to be a necessity, though it's faster heating. It's also hot enough to do damage if one isn't careful, esp to winding insulation, etc.,. even with propane.

[Duane Bozarth]

...

IMO, the primary advantage of the hotter flame is you can use smaller tip and get the part you want hot faster before the rest heats up. W/ a cooler flame it takes so long to heat conduction is carrying it away where you don't want it as fast as you can warm it up...

[George E. Cawthon]

Or you could put dry ice on the bolt. Put continuous torsion on it while it is cooling and it might just fall out when it shrinks.

[JerryL]

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I used to run into this all the time in my former business. Heat the bolt till it's cherry red and then splash cold water on it. The bolt will expand with the heat and contract with the cold. It'll come out like a baby.

[frank1492]

Thanks all for your really wonderful ideas. I am saving all of them for future reference. The stainless bolt was threaded into the end of a very old dishwasher motor. The washer is at least 20 years old, and although Sears still has the parts, I wanted to avoid buying a new motor. I am afraid the idea of having to do a really good job of drilling (esp. through stainless) to get a perfect job was a bit too scary for me, in the event your remedies should fail. Here's what I did. The bolt was used to hold two impellers, with fairly heavy plastic hubs. So I threaded the stub, got a piece of brass, went to my old Atlas metal lathe, and made a small "cap" bolt with internal threads that I screwed onto the stub. (What's the correct term for this item? Anybody know?) I then drilled the impeller holes slightly larger to fit around the internally threaded "cap". (Could do this perfectly as the impellers could be chucked in the lathe.) Sawed a slot in the end of the cap for tightening. This all took a couple of hours, but it came out very well and my blood pressure was kept in check. BTW all bolts have been well-coated with Permatex 2 before insertion this time. I feel a bit guilty that you guys spent so much time with your great suggestions, then I end up using none of them. I just didn't want to take any chances! I'm sure many others will profit from your great ideas. Thanks again. Frank

On Mon, 17 Jan 2005 15:00:58 GMT, "Noozer" wrote:

[ameijers]

(snip)

Chuckle- you sound like my brother, who also keeps an old lathe out in the garage. He'll spend hours making a part, just to see if he can, before he will buy one. Hey, it's cheaper than a shrink, and probably better therapy. :^)

aem sends...