It is a common misconception that heating a bolt with a torch will loosen it. This is not the case. Heating a bolt could make it harder to remove. The reason for this is that when metal is heated, it expands. This expansion can cause the bolt to become tighter in its hole. The only time this wouldn't be the case is if the hole is also heated, which would cause it to expand. So, the next time you're trying to remove a bolt that is stuck, skip the torch and try another method.