When you live in a place like Cincinnati where some winters it seems like the layer of salt on the road is about as thick as the snow, you probably know a thing or two about holey exhaust systems. Even if you hose off your car after every drive through salty slush, it will eventually still start to eat away at the undercarriage of your car. And nothing seems to be eaten away quite as quickly as the exhaust system. From holes in the exhaust pipes, to holes in the muffler, nothing turns your refined saloon car into a something that sounds like it could compete at Le Mans quite like an exhaust system that resembles Swiss cheese. So, when you bring your car to your favorite auto repair shop and tell them that your Jetta suddenly sounds like a Ferrari, here are some of the possible culprits.
The Many Pieces of Your Car’s Exhaust System
Before you figure out what could be causing the problem, you have to know what the parts are. Those parts that most people are familiar with in the exhaust system are the most visible parts—the muffler, and the pipes leading directly from it. What may not be immediately obvious are all of the other parts that are essential to making the modern car both more fuel efficient and road legal. As you may have guessed, the exhaust comes directly from your engine, and as with any cars with engines in the front, it has a ways to go to get back to the rear of the car where it can safely be released. From the engine, it hits a few different areas before it makes it out the tailpipe at the rear of the car.
Let’s take a look at the players:
- First we have the exhaust manifold. This bad boy is attached directly to the engine, and takes all of the exhaust from each of the cylinders and funnels it along into one pipe. The way that it is shaped is carefully carefully considered during the car’s engineering process. For example, if the pipes are too small it can reduce the velocity at which the exhaust exits the engine, leading to a reduction in power as well as a greater likelihood that there will be exhaust still in the engine chamber when the new intake occurs—which will also reduce overall efficiency.
- Next, or nearly so, we have the catalytic converter. Catalytic converters help to reduce the amount of toxic gasses that are emitted from an internal combustion engine into the atmosphere. They use the heat from the engine—the temperature of the exhaust has to be at the 300° F mark or higher to work properly—and science to pull the nastiest of the smog forming chemicals out of the exhaust and trap them before they hit the air. If you’ve ever been lucky enough to witness a parade of classic cars from the pre-catalytic converter days you know they look amazing, but the difference in noxious fumes from the classics in comparison to those cars from the modern day can be pretty significant.
- Along the length of the pipe—usually found both before and after the catalytic converter in modern cars—are oxygen sensors (or O2 sensors). As you may have guessed, these sensors monitor the amount of oxygen that is going through your exhaust pipe in comparison to the amount of oxygen in the air. In addition to allowing engines to see how the air-fuel ratio in an engine is going (leading to greater fuel efficiency) the sensor after the catalytic converter makes sure that the scrubbing abilities of the converter are actually working. If there is anything wrong with your O2 sensor, a warning light or check engine light will likely come up on your dash.
- From there, more exhaust pipe follows, which will have at least one resonator placed along its length. A resonator often looks like a wider section of a typical exhaust pipe, and works in concert with the muffler to adjust your car’s sound. One of the main purposes of the resonator is to reduce the sounds coming from the engine before it hits the muffler. In addition, it can change the overall sound of the noise coming from the engine, reducing or getting rid of any annoying droning or buzzing sounds before they emerge to drive you crazy.
- When the rest of the exhaust pipe makes its way towards its final destination, it meets one of its final barriers before reaching the outside—the muffler (or perhaps a silencer if you are driving a very British Aston Martin). One of the most easily recognizable parts of any exhaust system, it is a metal drum that can usually be seen from the rear of the car. The muffler is your final defense from an overly loud engine. It uses a series of tubes to reflect the sounds that the engine makes and uses this reflection of sound frequencies to cancel some of them out. This is why it makes such a difference in the sound of your car even if there is a relatively small hole in your muffler. The shape of the muffler has to be carefully calculated to reflect and cancel out the sounds properly. Putting a hole in the mix changes the sound frequencies and ruins the effectiveness of the whole noise reduction system.
- Last but not least, we have the tailpipe. Extending directly from the muffler, the tailpipe is the exhaust’s last thoroughfare before it reaches the outside.
The Rumble Became a Roar: Signs Your Exhaust System Needs Work
So, let’s say you are driving along and the pitch of your engine changes. Maybe you’ve hit a bump, maybe you’ve pressed hard on the accelerator once the passing lane arrived. Your cultured saloon car suddenly sounds a great deal more aggressive than it did before. If you leave off the gas and it quiets down, there is a definite possibility it is your muffler. But don’t take our word for it. If your car ever sounds weird—whether you think its the exhaust or something else—its a good idea to bring it to your favorite auto repair shop to get it checked out.
In addition to annoying your neighbors (which for you may be a positive) a leaky exhaust system could allow some of that noxious exhaust into your car’s cabin. The carbon monoxide produced from your car’s exhaust is dangerous, and if it quickly fills up the small space in your car, it could make you pass out while you are behind the wheel. There is a reason your tailpipe is in the back of your car. Our advice is, if you aren’t sure, take your newly noisy car to a car repair specialist. A professional should be able to lift up the car to inspect the system and give you an idea of what is wrong in the time it takes the average car enthusiast to dig out their jack. Take it to an automobile repair shop you trust and get it done right the first time.
