When a car, truck or piece of equipment is not taken care of properly, it can rust. While removing rust along the body is fairly easy, removing rusted bolts within them is not. When a bolt begins to rust, its threads adhere to the hole it sits in, making it almost impossible to remove by hand.
Apply heat directly to the rust. Heat the rusted bolt with a small blow torch. Heat the bolt until it turns red. While wearing protective gloves, unscrew the bolt with a wrench. It make take several times with the small torch to loosen the bolt.
Spray a penetrating oil like WD-40, Liquid Wrench or Kroil over the bolt, then tap the head of the bolt with a wrench. This will help the oil work its way along the threads of the bolt. Leave the oil on the bolt for at least ten minutes, then remove with a wrench. Be careful when tapping the head of the bolt. If you use too much force, the head could break off.
Strike the side of the bolt’s head with a rubber mallet. This will shake away loose rust. If you hit the bolt head to hard, it will break off, making it even more difficult to remove. Strike the bolt gently, from various sides, then remove it with a wrench. Repeat until the rusted bolt is free.
To remove the rust, pour hydrogen peroxide over it. Let the bolt set for 5 minutes and then scrub with a wire brush. Use a quick back and forth motion with medium to firm pressure. Apply more hydrogen peroxide and continue to scrub with the wire brush. Once the rust is gone, remove the bolt with a wrench.