Your Corner Wrench: Fighting seized fasteners with flame, force, or fluid

Article content

You don’t have to be a shade-tree auto tech to have a horror story about rusted screws that busted a few knuckles and clouded the air with some choice blue language. Fortunately, most well-equipped home garages will have the right tools to get things loose when some oxidized bolt or nut needs a little persuasion. Sometimes, however, having too many options can lead to the wrong decision.

Article content

When it comes to freeing up something metal that’s seized, there are usually three options: flame (meaning heat from a gas torch), force (impact tools/hammers), or fluid (penetrating oil or the like). Which one is the best depends on where the criminal bolt/nut is located, and what’s near or connected to it.

We apologize, but this video has failed to load.

Try refreshing your browser, or
tap here to see other videos from our team.

Your Corner Wrench: Fighting seized fasteners with flame, force, or fluid Back to video

One of the most common mistakes comes when applying brute force to remove a seized bolt or nut is to start by trying to loosen it first. Try tightening it a quarter of a turn before switching to the other direction. It can make all the difference between success and a broken bolt. If it’s a long rusted bolt, use a wire brush to remove as much rust as possible from the threads. There’s nothing worse than successfully getting a rusted nut to move, only to break the bolt when the nut gets caught on some rust only a few threads from the end.

Article content

Usually — and correctly — techs will only resort to flame as a last choice, especially with smaller diameter nuts and bolts. The problem with torches is the challenge of heating only what needs the heat. Heating a bolt and nut at the same time causes both of them to expand, resulting in a tight fit (the opposite of the intended result). Furthermore, too much heat can weaken a bolt and cause it to snap when a wrench is applied. And then there’s the matter of what might be in close proximity to whatever you’re trying to heat.

Most know that plastics and other non-metal materials have a lower tolerance to heat and can melt, but different metals can also pose problems. Aluminum, for instance, has a lower melting point than steel and seldom gives any warning before suddenly turning to liquid when too much heat is applied. Also troubling are the fire and explosion hazards that exist within a vehicle’s various fluid reservoirs, but don’t forget that some of these liquids can also give off explosive vapours when lines are heated.

Article content

Unless you’re an experienced torch hand, stick with propane flames and stay away from oxy-acetylene units. The latter are designed to cut through steel and other metals, and it’s very easy to go too far. Propane might take a little longer, but it’s definitely safer.

A more recent development in tools to beat seized fasteners is found in hand-held magnetic induction heater kits. These are the ultimate in safety, as their electromagnetic fields can turn a medium-sized bolt cherry red in seconds without transferring heat to surrounding areas or risking blowing yourself to smithereens. Quality kits start at around $200, and their portability makes them handy for any number of jobs around the house.

Fluids such as penetrating oils can be the ultimate in freeing stubborn nuts and bolts, as long as you make the time. Spraying rusty suspects several days in advance, once a day, will give their chemicals time to do the job so yours becomes much easier. So, for example, if your project day is Saturday, start spraying those nuts and bolts on a Monday and be sure to follow up daily.