Using a Hot Torch to Loosen Stuck Bolts

Apprentice glass blower wearing mask and using lance
Monty Rakusen / Getty Images

Some bolts just won't budge. They are stuck, seized, stubborn, rusted, corroded, and otherwise impossible to remove. There are a number of oils and penetrants that can really help, and a good soaking should always be your first line of attack. If those actions fail, however, it may be time to break out the propane torch and use some heat.

To remove a really stuck bolt, get some good penetrant—nothing works like PB Blaster—and a propane torch, available at any hardware or automotive stores. You can also use a butane torch, but it's a little cheaper and easier to go with the propane.

Safety Tip

Be extremely careful with an open flame! Never use an open flame near a fuel or brake line. Flammable fluids and open flame don't mix. The flame will burn anything rubber it comes into contact with, including trim, seals, and wire sheathing. It will also ruin paint instantly.

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Assemble Your Torch

Screw nozzle onto tank.
Be sure to close the valve before you screw the nozzle onto the tank.

Matt Wright

Whether you purchase a preassembled torch or a kit, try to get one with a built-in igniter. Otherwise, you'll have to purchase a separate hand spark, and that's just one more thing to keep track of. If you bought a kit, you'll need to screw the nozzle onto the top of the enclosed propane tank.

Be sure to turn the valve on the nozzle all the way to the right—the "Closed" position—before you screw it onto the tank. If you neglect to close the valve, you'll start to lose gas as soon as you screw it on.

Otherwise, don't worry about leaking propane. The tank will remain sealed until the nozzle is all the way on. At most, you may catch a whiff of gas in the air.

Before you light your torch, spray the stuck joint with PB Blaster penetrating oil. Give it a few minutes to work before you apply heat.

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Soak Up the Excess Juice

Soak up the excess penetrant.
Use a rag to soak up the excess wetness.

Matt Wright

Before you fire up the torch, soak up the excess penetrant with a rag. It's not super flammable, but it will flame up if there's a lot of unevaporated liquid present. Don't worry about getting every damp-looking area, just sop up the majority of it to be safe.

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Fire Up the Torch

Turn on the gas.
Adjusting the gas output for lighting.

Matt Wright

Now light the torch—and to go slowly and pay extra attention to what you're doing. Safety should always be the first priority. Hold the torch firmly, with the nozzle pointed away from you and away from anything that could ignite. Turn the adjustment nozzle counterclockwise until you hear the hiss of gas coming out of the torch. If you bought the self-igniting assembly, just click the starter button with your trigger finger and it will light. If you didn't buy a self-igniter, use your hand spark to ignite the gas off by holding the sparker directly in front of the torch.

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Adjust the Flame

Propane torch flame adjustment.
A nice, clean propane flame.

Matt Wright

Once your torch is lit, adjust the flame using the adjustment dial on the torch unit. Turn it counterclockwise for a bigger flame, clockwise for smaller. You don't need a huge flame for the job, so adjust it until you have a small, clean flame. A clean flame is mostly blue and burns steadily and evenly.

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Torch Your Stuck Bolt

Heating the bolt.
Using a flame to loosen the bolt.

Matt Wright

Now heat the bolt and nut. Put the flame directly over the stuck part, or the part you can get to safely. Heat it for 30 seconds or so and it should free up easily. If it doesn't, repeat the process to see if that helps. Repeated heating and cooling sometimes does the trick.