The constant heat, vibration and moisture of a car's exhaust system means that there is a good chance that the bolts that mount the muffler to the rest of the exhaust system will become stuck. It is quite rare for muffler bolts to be removed easily. There are several tips and tricks you can use to remove muffler bolts before you have to resort to cutting them with a hacksaw.
Spray the muffler bolts with a penetrating lubricant before you begin working. Soak them thoroughly and give them a few good hard taps to allow the lubricant to begin working its way in. Let the lubricant work for several hours, if possible. You can even leave it overnight.
Try leverage first. If you stabilize the bolt very firmly, such as by wedging a tight-fitting crow's foot wrench against the bottom of the car, you may be able to get a lot of force onto the stuck muffler bolt by using a breaker bar. Use a tight-fitting socket or crow's-foot wrench to avoid stripping the bolt or nut.
Extend the leverage arm of a breaker bar with a length of pipe if you cannot get enough force on the stuck muffler bolt. A two-foot metal pipe slid over the end of the breaker bar will significantly increase the amount of force you can apply to the stuck bolt.
Heat the muffler bolt with a propane torch if you can't remove it with wrenches or sockets. Lower the muffler as far as possible to avoid scorching the underside of your vehicle. Apply heat directly to the bolt and nut. Once the bolt is hot, try again with wrenches and sockets.
Cut the stuck muffler bolt off if everything else fails. A rotary cutter, such as a Dremel, is the perfect tool for the job. Try cutting the nut off of the bolt first; once it is clear, you may be able to pound the bolt out with a hammer. Cut the head off as a last resort.
