What is a muffler and where is it located?

A muffler is a key part of your vehicle’s exhaust system and is usually located underneath the vehicle towards the rear. It is mounted to the undercarriage of the automobile with a hanger bracket and clamp. Milton and Marshall Reeves, brothers from Columbus, IN, were granted the patent for a modern automotive exhaust muffler back in 1897. For an idea over a century old, the basic idea of a muffler has changed very little.

Your exhaust is responsible for keeping the thousands of explosions taking place inside your car or truck’s engine from deafening you and everyone around you. It does this by routing the sound pressure your engine creates when it’s busy turning fuel into forward motion through a muffler, which in turn minimizes the noise. In a standard automotive muffler, the inside of the canister is designed with a series of chambers lined with insulation and tubes consisting of numerous perforations, or baffles. The pressure waves produced by the activity of the engine, in addition to the exhaust gases, enter into the muffler and are bounced around, creating reflected sound waves of a roughly equal nature that move in opposite directions. When the waves interfere with one another, they cancel each other out by the time they exit the muffler, thus reducing the sound that comes from the engine.

Automobile exhaust systems are also responsible for keeping all the nasty byproducts of internal combustion moving out the back of the vehicle and into the atmosphere through the muffler and then the tailpipe. This keeps the exhaust gases from building up in the passenger compartment, which is a good thing considering the lack of breathable air in car exhaust.

Because the engine’s exhaust gasses and sound pressure waves share the same complicated and restrictive pathway through the chambers of the muffler, unavoidable backpressure is created. If the vehicle is not tuned for it, backpressure can actually decrease the performance of an engine. It is for this reason that performance mufflers exist. They most commonly have a straight-through design that reduces backpressure. However, with an increase in power usually comes an increase in exhaust sound from the engine so there is certainly a trade-off when it comes to automotive mufflers.

How do I know the muffler needs to be replaced?

The obvious answer to this question is “when people shudder upon hearing the terrifying noise that heralds your arrival, wherever you go.” As typical automotive mufflers are under the vehicle and exposed to all manner of corrosive salt or road grime while driving, rust is one of the main reasons for needing to replace the muffler on your car or truck. Exhaust gases can escape through a rust-hole, making for a loud commute or less than ideal atmospheric conditions. Welds can crack, rocks can dent and salts can corrode. Any of these unfortunate situations can call for a replacement muffler.

Because of its location, it’s usually “out of sight, out of mind” when it comes to mufflers. Buck that notion and have a look under your vehicle from time to time to check on the condition of your muffler. If it has rotted out and looks like it’s about to fall off, it’s time to replace it.

Can I replace the muffler myself?

The muffler can be replaced by the average do-it-yourselfer. The first step is to apply penetrating oil to the muffler bracket since the bolts will most likely be rusted. Remove the bolts with a socket and extension. The muffler will be supported by brackets or rubber studs, and the next step is to get the muffler free. It should then slide down and out. Before reinstalling, make sure the muffler has a flange gasket. Then manuver the bracket into place and line the muffler up. Attach the muffler to its support brackets, and once it's stable, tighten the bolts to the muffler bracket. After the repair is completed, start the car and check for any leaks.