a4944

Hi All,
What's the proper way to use heat to free up frozen bolts and/or nuts? Specifically, I have a crankshaft bolt giving me trouble and I want to use heat. Should I heat the bolt and attempt to remove it while it is hot or should I quickly cool it down before trying to remove it? I've read through old posts and seen both of these techniques suggested.

In this case there could be loctite on the bolt or the bolt is just over-torqued. I think heating the bolt would break down the loctite but would it help at all if it's just over-torqued?

I'm interested in other applications of heat such as on suspension components also. For suspension components, is it best to heat the nut rather than the bolt? Is heat primarily used to break down rust?

Thanks,
Mark

Rip It

Just past the blue inside flame is the hottest. I suspect applying heat is to get the parts moving with expansion, however I have my doubts about u getting a bolt attached to the crank shaft very hot. The crank is going to be a great heat sink. A tool & die maker told me penatrating fluid and hitting with a hammer breaks rust loose, repeat daily.

f1rocks

Did you try a bigger bar?

Mine took a 7ft bar to break loose.

951North

Like I said before my friend, get a MAPP/OXY torch and a long cheater bar. As for the hot/cold thing, I can't say, I guess the risk is you could twist off the head of the bolt if it's too hot, I've always just got the seized bolt up to orange, and by the time I got the socket on it it had cooled to a dull red..... Sounds like it may be approaching the "remove front of car and get an impact gun on there" or pull engine, I don't know what would be harder....

turbo8

mine as i remember, took a big impact wrench or a big breaker bar.
heat the nut not the bolt if you want to use heat

a4944

I was torque limited by the cheap 6pt socket I tried. It broke. I'm waiting for a Craftsman socket I ordered to come in. I would like to learn how to use a torch effectively as I have never tried to use one. I have had cases in the past where I had to take the car to a shop because I could not free a tie rod end or suspension bolts so I want to learn more about using a torch in general.

951North, I saw the MAPP/OXY torch at Lowes. I read the label and it sounds pretty potent since it can be used for welding and thin metal cutting. I was thinking about starting out with MAPP only since I don't have any experience with torches but want to learn. The manufacture guide said to use MAPP for frozen bolts. I'll try the MAPP/OXY though if you think MAPP won't be enough. Is the MAPP/OXY torch a good general purpose torch for all seized bolts? Can I use it on frozen tie rod ends? The price was resonable so it's only my experience level that concerns me.

Thanks,
Mark

Ben Z.

Just remember that you will be eliminating any strength improving heat treatments done on a bolt if you get it too hot.

Tom M'Guinn

Not an expert, but as far as I understand, heat is used to (a) melt loctite and break down other adhesion issues, and (d) to expand metal. If you can get a flame on the metal surrounding a bolt for example, you can expand the bolt hole, which helps the bolt come out. For example, when removing head studs, you put the heat on the side of the block down where the stud threads are. Some of the heat transfers to the bolt/stud also, which breaks down the loctite. Heating a bolt head sometime helps free up stuck bolts, but it also expands the bolt in the hole and works against removal. As for the crank pulley bolt, just get a long pipe and cut it so it just clears the hood. Then pull with all your might.

Techno Duck

Mark, i would reccommend using a bigger breaker bar as noted above. Honestly i dont think a torch / heat will help much on that bolt. I was lucky to be able to break mine free with a 18-inch 1/2 drive breaker bar. It took a fair amount of muscle from all 150lbs of my lanky skinny self, but i was able to break it free. It helps to use a deep socket also, i find extensions dont work well with breaker bars.

Leverage is everything!

Scootin159

For reference....mine took a 8' breaker bar w/ me jumping on the end of it, and it still BARELY moved.

lart951

I used the bar from my 3 ton jack, it worked miracles. It was special tool's idea it was so easy with the big bar.

951North

I don't think there is much insulation between the bolt threads and the crank threads therefore heating the whole area shoud expand everything... But like I said getting seized bolts orange-hot then letting them cool to red glow expands and contracts the metal thus making the removal easier. Yes heating a bolt/nut that much will probably hurt any heat tempering originally in the hardware.

go for the Mapp/Oxy w/ just propane you'll be there all day at the temp isn't high enough and you'll only put all the heat into the crank itself, the intense temperature of the mapp/oxy will put the same amout of heat into the system in a much shorter period of time thus not allowing the crank to "soak up" as much heat...

YMMV.

jason

Tom M'Guinn

Don't disagree, although I imagine the metal under direct heat gets hotter, and when steel bolts screw into aluminum (like head studs) I think the aluminum expands quicker/more.

Mike S

Don't mess with the heat. Use a long good quality breaker bar with a steel pipe over it for leverage if needed. You should also use impact gun sockets so you don't ruin the normal ones.

a4944

The better socket came in and I got a 5 ft section of pipe and I was able to get the bolt off without heat. I did get the MAPP/OXY setup and used it on another car to break something free. The hot part is by the blue flame but then the yellow flame gets everywhere. I didn't feel I had enough room to use the torch on the crankshaft bolt since you have to light it and I would have to swing the flame into the pulley.

I wanted to use it on a pinch bolt on the other car by ball joints but I was concerned with the yellow flame hitting the rubber boots of the ball joints if I use the blue flame to heat the area around the pinch bolt. Am I using this wrong? Will the flame that scatters off the metal be hot enough to damage rubber hosing and boots?

Thanks,
Mark