What Is An Exhaust System?

A vehicle exhaust system works to collect and expel the gases produced in every internal combustion engine. Not only is it essential to get rid of harmful products, but it's also in line with global regulations to minimize harmful emissions. The entire exhaust system consists of the exhaust manifold, catalytic converter, muffler, sensors, and exhaust pipes. Vehicle mufflers also reduce noise from the whole setup. Maintenance is essential to prevent exhaust problems and a costly repair. This guide will help you understand the basics of your exhaust system and how to spot and fix exhaust issues when they arise.

Parts Of An Exhaust System

As an internal combustion engine (ICE) uses the ignition of fuel to drive pistons that produce energy, the byproducts formed in the process need to be expelled safely. This system takes care of that. Numerous components make up an exhaust system, including:

Exhaust Manifold

This is the part closest to the engine block and is the first step in the emissions process. It attaches to the cylinder head, collects the fumes released from the cylinders, and will burn up any unburnt gases. The exhaust manifold will then direct these gaseous outputs either to the catalytic converter or turbocharger (if the engine is turbocharged). How the exhaust manifold is designed is quite important to performance, and some larger engines may have two exhaust manifolds. Manifolds are mostly made of stainless steel, aluminum, and cast iron to allow them to withstand high temperatures.

Oxygen Sensor

These are an essential part of any modern combustion engine, and there are generally at least two of these in the system, although V6 or V8 engines with two manifolds will obviously have more. The first oxygen sensors are found in the exhaust manifolds. By measuring how much oxygen is present in the exhaust fumes, the onboard computer can determine if more or less fuel is necessary to achieve maximum efficiency and performance. The other sensors are found after the catalytic converter.

Catalytic Converter

Gases from the engine can be reused in turbocharged cars, but we deal with turbocharging in our in-depth post here. In non-turbo cars, exhaust gases are directed to the catalytic converter from the manifold, where a combination of catalysts is used to reduce the harmful emissions. At this stage, hydrocarbons and carbon monoxide are transformed into water and carbon dioxide, while nitrogen oxides are reduced in the process. Emissions regulations mean catalytic converters are a requirement on all cars.

Cars that run on diesel, such as the Jeep Gladiator EcoDiesel or Ford F-250 Super Duty, have a diesel particulate filter additionally, which serves to capture the heavier elements found in diesel such as soot and ash. You can read more about diesel particulate filters here.

Exhaust Pipe

There are numerous pieces of pipe that connect all the components in the system. These are commonly referred to as exhaust pipes and run along the length of the underbody of your car.

Muffler And Resonator

Mufflers are added to reflect and absorb the majority of the sound traveling through the system. Oftentimes, this is not sufficient and a resonator needs to be added, too. The latter focuses specifically on eliminating high-pitch frequencies, humming, and buzzing. These work together to dampen some of the harsher engine sounds.

Exhaust Outlet

The final pipe tip is where the product of the entire system is finally expelled. This is usually at the rear of the vehicle, and sometimes dual outlets are installed as often seen on sportier models. On trucks, these may even be positioned on the sides instead. Naturally, electric vehicles don't have these (or have faux-exhaust tips for looks), as there are no emissions to expel in EVs.

Exhaust System Diagram

This diagram of a typical exhaust system.

Potential Exhaust Problems To Look Out For

As with any complex mechanical system, problems are bound to crop up from time to time. They could be as simple as a build-up of rust or as severe as a complete exhaust system failure. Knowing how to spot them and what steps to take to remedy them is essential. Here are some of the most common problems:

• Exhaust leaks: These can be caused by rust, driving over rougher terrain, or loose sections of the system becoming damaged. If the leak is situated in the manifold, you run the risk of having dangerous fumes entering the cabin. And, since the exhaust dampens the sound as well as expels gases, a harsher sound will be evident if there's a leak. If the problem is not severe, a pipe repair kit, purchased from an automotive shop, can be used. Otherwise, a replacement will need to be purchased and fitted.
• Faulty sensors: Without sensors, the computer cannot determine the right mixture of air and fuel, and the result of this could be using too much fuel or a clogged catalytic converter.
• Exhaust smoke: While smoke from the exhaust is usually an indicator of a problem elsewhere in the engine, it's a good diagnostic tool. Be sure to read our post on what the different types of smoke on your car could mean, here.
• Hangers breaking: The hangers are the little bits and bobs that keep your exhaust system neatly tucked away and out of harm's way. If one or more of these break, everything can move around, not only sounding terrible as it knocks about but leading to cracks and breakages along the exhaust system. Inspect these often to make sure it's all in good condition.
• Vibrations: When the exhaust system has a severe problem, your whole car can be impacted. This is sometimes translated through vibrations on the gas pedal, and even the steering wheel. Getting a mechanic to determine the exact cause is wise.

Conclusion

A vehicle's exhaust system isn't there just to make it sound quieter; it serves an essential role in operations as well as ensuring the car meets roadworthiness and emissions regulations. Specialized systems can even improve the overall specs of a vehicle by increasing engine outputs or fuel efficiency. If you want your car to run at its best, it is important to maintain and regularly check before a repair to an exhaust system is needed, or the system has already failed.