Freeing Rusty Fasteners With a Blow Torch | Articles

Despite the often-shared advice about not buying rusty project cars, sooner or later you’re bound to encounter one. And those rusty cars are filled with rusty, crusty and cruddy fasteners–the kind that can rarely be loosened, even with chemicals. There is another option, though: the hot wrench. We’re not talking about a propane or MAPP torch. While these low-buck torches have their place, they typically can’t generate enough concentrated heat to deal with rusty fasteners. A full-blown oxygen/acetylene outfit is usually our tool of choice. Conventional wisdom says that heat expands the fastener and helps it come off, but the reality is a little different. Yes, the fastener expands, but its mating part usually does as well, so that’s not much help. The key instead is to apply just enough heat upon exactly the right area–for example, to the nut but not the bolt–so expansion works in your favor. Meanwhile, heating up rusty fasteners can actually burn away most of the corrosion.

Tools of the Trade

Here are two popular oxygen/acetylene torch kits. On the left is a traditional shop kit with fairly large tanks. There typically run about $350 to $500. On the right is a portable setup; it offers the same capabilities plus grab-and-go convenience, but expect it to run out of gas at exactly the worst time. (Our advice: Keep spare tanks on hand.) These smaller rigs cost about $250 to $400 or so.

…