Heat on a seized bolt
Discussion
I've got a seized alternator bolt on my MR2 and, having tried various penetrating oil and brutality, I'm going to resort to heat. I've never done this before though so I'm after a bit of advice. Do I heat the bolt? Heating the bracket around the bolt seems to make more sense. Do I go at it while it's still hot? How hot? Will a normal 'plumbers' blow torch do the job?
No two guides I can find seem to be consistent.
No two guides I can find seem to be consistent.
Try heating the bracket around the bolt and melting a candle on the heated metal. The wax will act as a lubricant. You can then turn the bolt (while its still hot). You may need to repeat this a few times as when it cools it might get stiff again.
ETA: A plumbers blowtorch should be fine thats what i've used in the past. The amount of time it will need to be heated will obviously depend on the size of the bracket.
ETA: A plumbers blowtorch should be fine thats what i've used in the past. The amount of time it will need to be heated will obviously depend on the size of the bracket.
Edited by xeon on Wednesday 13th July 23:03
Hard to say without seeing it, but I always direct heat at the thread.
My understanding is that the heat causes the nut and bolt to expand and breaking the seal of rust.
I use an ordinary propane plumbers blowtorch when trying to undo pump union nuts which are Inch and a Half in size.
Silly suggestion, but have you tried hitting it with a hammer or tightening it slightly?
My understanding is that the heat causes the nut and bolt to expand and breaking the seal of rust.
I use an ordinary propane plumbers blowtorch when trying to undo pump union nuts which are Inch and a Half in size.
Silly suggestion, but have you tried hitting it with a hammer or tightening it slightly?
I have used heat recently with excellent success. Seven turbo to downpipe nuts and eight exhaust manifold stud nuts. Was expecting to snap a few, but came away with all of them going back on without issue. 
My technique is to soak in plusgas, heat with a heatgun for a couple of minutes, a bit of extra plus gas and turn with a breaker bar. Obviously the size of the nut/bolt etc will dictate if you can use the bar or not.
My technique is to soak in plusgas, heat with a heatgun for a couple of minutes, a bit of extra plus gas and turn with a breaker bar. Obviously the size of the nut/bolt etc will dictate if you can use the bar or not.
Heat the nut, or in your case the bracket. An ordinary propane blowtorch should do, like you can buy in any diy store.
Heating the bolt is fine as long as you're in the vicinity of the threaded part. Usual rules of safety apply, no flammable substances, no prolonged heating of parts of the vehicle which may catch fire, don't melt the leads etc etc, keep a fire extinguisher handy, that sort of stuff.
Oh, and when you try to shift the bolt use shock not torque i.e hit the spanner with a hammer, don't just twist with brute force.
Heating the bolt is fine as long as you're in the vicinity of the threaded part. Usual rules of safety apply, no flammable substances, no prolonged heating of parts of the vehicle which may catch fire, don't melt the leads etc etc, keep a fire extinguisher handy, that sort of stuff.
Oh, and when you try to shift the bolt use shock not torque i.e hit the spanner with a hammer, don't just twist with brute force.
Heat to a dull red or sometimes less than that but as soon as the heat is off QUENCH immediately and thoroughly with water. It works EVERY TIME. I was an engineer almost 20 years before another older and therefore more wiser engineer friend of mine gave me that invaluable technical info. I had heated plenty of siezed threads up till then even up to 4" bsp but as soon as I loosened the first exhaust stud that would have definitely snapped off without that method I was educated....... Thanks to Ken Smith engineer extraordinary.
Incidentally two Farmers - brothers one said to the other -You'll never get them undone ( on an old tractor) exhaust system...... He said yes I will - Mick's given me a tip...... half hour later all fixings and the manifold was off. Not one stud broken.
Incidentally two Farmers - brothers one said to the other -You'll never get them undone ( on an old tractor) exhaust system...... He said yes I will - Mick's given me a tip...... half hour later all fixings and the manifold was off. Not one stud broken.
Mick50NCD said:
Heat to a dull red or sometimes less than that but as soon as the heat is off QUENCH immediately and thoroughly with water. It works EVERY TIME. I was an engineer almost 20 years before another older and therefore more wiser engineer friend of mine gave me that invaluable technical info. I had heated plenty of siezed threads up till then even up to 4" bsp but as soon as I loosened the first exhaust stud that would have definitely snapped off without that method I was educated....... Thanks to Ken Smith engineer extraordinary.
Incidentally two Farmers - brothers one said to the other -You'll never get them undone ( on an old tractor) exhaust system...... He said yes I will - Mick's given me a tip...... half hour later all fixings and the manifold was off. Not one stud broken.
I reckon he's probably got it sorted after 9 years Incidentally two Farmers - brothers one said to the other -You'll never get them undone ( on an old tractor) exhaust system...... He said yes I will - Mick's given me a tip...... half hour later all fixings and the manifold was off. Not one stud broken.
RazerSauber said:
Mick50NCD said:
Heat to a dull red or sometimes less than that but as soon as the heat is off QUENCH immediately and thoroughly with water. It works EVERY TIME. I was an engineer almost 20 years before another older and therefore more wiser engineer friend of mine gave me that invaluable technical info. I had heated plenty of siezed threads up till then even up to 4" bsp but as soon as I loosened the first exhaust stud that would have definitely snapped off without that method I was educated....... Thanks to Ken Smith engineer extraordinary.
Incidentally two Farmers - brothers one said to the other -You'll never get them undone ( on an old tractor) exhaust system...... He said yes I will - Mick's given me a tip...... half hour later all fixings and the manifold was off. Not one stud broken.
I reckon he's probably got it sorted after 9 years Incidentally two Farmers - brothers one said to the other -You'll never get them undone ( on an old tractor) exhaust system...... He said yes I will - Mick's given me a tip...... half hour later all fixings and the manifold was off. Not one stud broken.
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