26 replies to this topic

[DarkHand]

My guess for heating the bolt is that yes it expands, but it 'budges' the bolt a little as it does. Enough to get it moving when you try and turn it.

[gtpilot]

The idea behind heating the bolt head...clamping pressure in a bolt is created by the stretching the threaded portion of the bolt - the face of the head against a "non-moving" surface while the bolt is being turned creates the stretch.

When a bolt has been sitting in one place, torqued down, for a long period of time the dissimilar metals and the salts, acids and everything else that has been in contact with the threads, bolt head and mating surface cause corrosion underneath the head bolt. When you heat the head bolt and the heat soaks down to the threads, the bolt expands - changing its length, the result is the lowering of the clamping force of the bolt. This makes the bolt easier to break loose.

If I understand your theory of heating the crankshaft, I think it is flawed...if you heat the crankshaft to the point that its internal threads expand, they length of the crank is going to grow - this is going to create more clamping pressure on the bolt because you are going to stretch ir more.

Kirk

[DarkHand]

Ahh I gotcha now, the bolt expands, while what it's bolted TO dosen't (much). The bolt now has a slightly larger diameter than what it's bolted to, making it easier to remove.

[Airjockie]

hemp huh?
where'd u get al that hemp?
and how would you know how easy it burns?

well i don't have and hemp...but i like your method.

You can get it at any Walmart, or other hardware stores.

If you burn nylon...it will just melt, and form into a ball or tar like substance, imagen that tar lik substance stuck on the top of the piston, and then it would form a hot spot, and weaken the piston in that area, or a valve...

Hemp is just like a old time rope material, many strands of a bark like substance...and when it burns, it just goes poof, ashes up, and dissapates thru the exhaust system.

[Rampage]

GTPilot: Thanks, that clears that up definately for me, for bolts.

The first time I ever successfully used my method (and times after again) I did on a bleeder screw for a caliper. They don't have heads and they aren't "stretched" in, so heating the caliper itself would free the screw, and it did.

However, stretching the bolt which is clamped down with a head on it makes sense.

Another instance was trying to remove a bolt from a control arm that was not threaded, in which case heating the arm would be better than heating the bolt.

Thanks again for clearing that up, something I will look for when trying to take out stuck threaded bolts with heads.

Cheers,
Mark

[Doodson]

one other method that I have used before is to just strike the bolt with a hammer once or twice and sometimes this loosens the bolt, Do not sit there and Beat on the thing though.

Doodson

[gtpilot]

Everytime I go to take a stud out of aluminum I strike the stud with a hammer face on to the end of the stud (like trying to drive the stud into the aluminum like a nail) before I try removing the stud - works like a charm.

Kirk

[E-AT_me]

i must try these methods.. i've been dousing the bolt every morning with PB blaster, so trying it tonight should get me somewhere.. maybe..

[boosted_zc]

I gotta chime in on the whole heating issue. There's no way in hell you'd ever see me put a torch to my crank. First of all if your putting a torch to the crank itself your liable to heat it up to much and melt your oil pump seal. Know heating the bolt is a much wiser thing to do. What i do seems to work well. First of all MAP gas is best, it's much hotter than propane. First i heat the bolt up pretty good to expand it, take it off and let it cool for a few minutes then spray it with some PB Blaster ( this stuff is godly). I'll let that penitrate for a few minutes and then put it through 2 to 3 more heat cycles. I figure multiple expansion and contractions cycles frees it up. I pretty much works everytime for me. But of course now i rely on my lovely impact,.... oh how i love thee so........ opps sorry having another moment.

[Airjockie]

Once you get the crankshaft stationary.......there is no need for heat, impact guns, PB Blaster or other knocker-er-up-an-loosen oils.....


The rope still wins, saves time and knuckles....

[RedRexDX]

airjockie and i did his method for both my civic and mirage. highly recommended.