Bolts and other fasteners seize up predominantly from corrosion. Corrosion forms on the fastener as it ages or is subject to repeated bouts of heating and cooling. The corrosion locks the fastener into place. When heavy corrosion forms, penetrating oils cannot free the fastener. Applying heat with an oxyacetylene torch to the fastener or the area around it causes the metals to expand, separating the corrosion and freeing the fastener. Although heat does free seized fasteners, too much heat can distort and destroy the part surrounding the fastener.
Turn on the acetylene and oxygen tanks, then put on your leather gloves.
Inspect the area that you need to heat with the torch. Look for flammable materials and gas lines in the area surrounding the seized fastener. Do not use an oxyacetylene torch near fuel lines or the vehicle's gas tank.
Turn on the acetylene at the torch. Light the acetylene with the striker. Turn on the oxygen. Adjust the oxygen until you reach a neutral flame.
Heat the nut or the metal surrounding the seized bolt. Keeping the torch head 2 to 4 inches away, move the heat completely around the part.
Remove the flame when the part has a low orange glow. Allow the part to cool.
Place the wrench onto the fastener. Alternate the wrench from loosening to tightening to work the bolt free. If the bolt refuses to move, repeat Steps 4 and 5. The bond will eventually break. Do not heat the metal to a bright orange; this will weaken the structure of the metal.
Set the fastener on a surface that won't be damaged by the heat. Dispose of the fastener when it cools.
