Heat for stuck bolts?

[fleabag]

I was screwing IN my gas tank and was having trouble as it was pretty warm outside. I gave up and then proceeded to work on the car again, this time it was a bit cooler outside and when I tried to screw it in again, I found that I was able to tighten it some more. This to me makes sense as the colder it is, the more the metal contracts, therefore allowing me to torque it more. This would seem to imply that it'll be impossible to unbolt the bolt if it was bolted in at a very low temperature and was attempted to be removed at a very high temperature.

However, if the above is true, why do people use blow torches in order to remove stuck bolts?

Moved to appropriate forum - Moderator Rubycon

 

[dmh1167]

Torches are good for taking out rusted bolts but usually it is best to heat one thing or another like a stuck nut on a stud heat the nut not the stud. A bolt heat the area around the bolt not the bolt.

One old cool trick on fly wheels for cars and trucks to remove the ring gear for the starter is to heat the old ring and tap it off to put on the new one set the flywheel in a cool place or shop fridge then heat the new ring till its good and hot then tap it back on to the fly wheel once it cools it will not come off till you heat it again.

 

[LTC8K6]

You heat a nut and it expands, making it easier to loosen.

For a bolt, you would need to heat whatever it's screwed into, not the bolt.

 

[Bignate603]

Originally posted by: LTC8K6
You heat a nut and it expands, making it easier to loosen.

For a bolt, you would need to heat whatever it's screwed into, not the bolt.

This.

Also, stuck bolts are often stuck because of corrosion or even electrolysis (bonding of dissimilar metals). Heat can cause that connection to break, allowing you to turn the bolt.

 

[jlee]

Originally posted by: Bignate603

Originally posted by: LTC8K6
You heat a nut and it expands, making it easier to loosen.

For a bolt, you would need to heat whatever it's screwed into, not the bolt.

This.

Also, stuck bolts are often stuck because of corrosion or even electrolysis (bonding of dissimilar metals). Heat can cause that connection to break, allowing you to turn the bolt.

The last time I put heat to something (axle nut), eventually the wheel was almost too hot to touch...I'm not sure how easy it would be to heat just one area!

We broke two 1/2" breaker bars on that nut, too...