I’ve got an old, rusty, stuck bolt that I just can’t get out. How can I get it out?
First, try tapping it with a hammer. If you really hit it hard, you’re likely to break it off.
Next, try using a combination of penetrating oil or WD40, a torch, a big hammer, and an impact wrench.
Warning: Penetrating oil is flammable! Be careful with the oil and the torch!
Also, be careful with the oil or WD40 because they will contaminate the surface, causing paint to look bad. WD40 has a tendency to overspray, leaving telltale spots on fenders and such.
As a last resort, you can break it off, and redrill and retap if necessary.
Most local hardware stores (especialy Ace Hardware) have a left handed drill bit collection. Just chuck it up, put the drill in reverse, then drill on the bolt. It usually grabs the bolt and turns it out by the threads after a few revolutions.
Warning: don’t use it with the drill in forward or the bit will burn up and be useless!
You might try tightening the bolt first a little after using penetrating oil.
Floyd Humphries: I have found that when you heat up a bolt, that if you cool it quickly with water, that it will come out extra easy.
Dick Williams: I just want to pass on something that works for me when removing very stubborn bolts. Heat the bolt with a torch – a propane torch will work on small bolts. Once the bolt is hot – just starting to glow red in really stubborn situations – then touch the threads with paraffin wax, with the bolt situated so that the wax runs down into the mating threads. Then remove the bolt. I used to use this method to remove drain plugs from engine blocks. It always worked. I’ve also used this to remove small phillips head screws that were corroded into pot-metal tail light housings.
JLS: Here’s an approach I’ve used successfully in the past: Weld a piece of metal to the top of the bolt. You can then still get some leverage on it after the head of the bolt is gone from applying other techniques.
Craig Forcht: When you get a broken bolt the easiest way to get it out is put a close fitting washer over the top of the bolt so it protects the surrounding material, then place a nut that is 1-2 times bigger than the actual thread of the broken bolt, then use a welder to weld to the broken bolt. Weld in short bursts so as not to weld it to the surrounding material. Keep zapping it untill the weld comes up into the nut, then weld generously and fill up the nut which puts enormous heat into the bolt but not the surrounding material. This makes the bolt expand. After welding let it cool completely, which makes the bolt contract and break the rust, then it should come right out. This method works great on exhaust manifolds. I’ve seen this method used to extract broken bolts down inside holes 2-3 times deeper than the diameter of the bolt.