Using a Hot Torch to Loosen Bolts

1
So Your Bolt is Stuck

rusty bolt
Loosen rusty nuts like these using a flame torch. Getty

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 to remove it. And a good soaking should always be your first line of attack. If that fails, however, it may be time to break out the propane torch. 

To remove a really stuck bolt, get some good penetrant (nothing works like PB Blaster) and a propane torch, available at your local home fix-it store. You can also use a butane torch, it's just 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.

2
Assembling Your Torch

Screw nozzle onto tank.
Be sure to close the valve before you screw the nozzle onto the tank. photo by Matt Wright, 2008

Whether you bought your torch as a kit or in separate pieces, you'll have a small tank of propane, a screw-on nozzle assembly, and if you don't have a built in ignitor you'll need a hand spark. I like the nozzles with a built in ignitor because it's one less thing to buy and keep track of.

All you have to do is screw the nozzle onto the top of the propane tank.

IMPORTANT: Before you screw it on, be sure to turn the valve on the nozzle all the way to the right (closed). If not you'll start to lose gas as soon as you screw it on.

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

3
Soak the Bolt with Penetrant

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

4
Soak Up the Excess Juice

Soak up the excess penetrant.
Use a rag to soak up the excess wetness. photo by Matt Wright, 2008

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.

5
Fire Up the Torch

Turn on the gas.
Adjusting the gas output for lighting. photo by Matt Wright, 2008

Now it's time to light the torch. Now is also the time to slow things down and pay attention to what you're doing. Safety should always be the first priority.

Hold the torch firmly with the nozzle pointed away from pretty much anything. Turn the adjustment nozzle counterclockwise until you can hear the hiss of gas coming out of the torch. If you were smart and bought the self-igniting assembly, just click the starter button with your trigger finger and it will light. If you went the cheap route, or you have sparkers on hand anyway, spark it off by holding the sparker directly in front of the torch.

6
Adjusting the Flame

Propane torch flame adjustment.
A nice, clean propane flame. photo by Matt Wright

Now that the torch is lit, you can adjust the flame using the adjustment nozzle (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.

7
Torching That Stuck Bolt

Heating the bolt.
Using a flame to loosen the bolt. photo by Matt Wright, 2008

It's finally time to 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 to loosen it up nicely. Unless you're having a really bad day, it should free up quickly. If it doesn't repeat the process to see if that helps. Repeated heating and cooling sometimes does the trick.

Safety Tip (again):

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.