THE EXHAUST SYSTEM

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The Function of the Exhaust System

In an internal-combustion engine fuel is ignited, creating a chain reaction of combustions that in turn drive the pistons & power the engine. The by-product created by this process is exhaust fumes, which is why the exhaust system is needed. The main function of the vehicle’s exhaust system is;
  • To create a pathway for toxic exhaust fumes from the engine, underneath the vehicle, & out & behind the back bumper; preventing the poisonous gasses from entering the inside of the vehicle & making the occupants sick.
  • To reduce emissions into the atmosphere.
  • To reduce the noise created by the fuel combustion process.

How does the exhaust system work?

The exhaust system is made up of 4 main components, connected through a series of pipes. These pipes are connected to the underside of the vehicle from the engine bay, & wrap around other important components of the vehicle (for example the axle). The average length of an exhaust system is approximately 3 metres, although generally only the exhaust pipe is visible. The main components of the exhaust system are the:
  • Exhaust Manifold or Header
  • Catalytic Converter
  • Muffler
  • Exhaust Pipe

Exhaust Manifold

The purpose of the exhaust manifold is to collect the exhaust gases from the engine cylinders & direct it through the exhaust manifold, into the one pipe on the other side, & onto the rest of the exhaust system. It is usually made of cast iron, aluminium or stainless steel.

Signs there is a problem with your exhaust manifold:

  • Small cracks can form over time from the extreme pressure & heat. These cracks can turn into small holes which can then cause complete failure.

Header

A header performs the same basic function as an exhaust manifold. However, in an exhaust manifold there are 4 or 8 cylinders all going into the one manifold & exiting through the one pipe. This creates a certain build-up of ‘back pressure’. The difference of a header is that each cylinder gets its own exhaust pipe & come together into a larger pipe called a ‘collector’. Each pipe is designed to be the same length, so that each cylinder’s gases are delivered into the collector at the same time; thus helping to eliminate the backpressure & letting the engine ‘breathe’ easier. It is usually made from lightweight stainless steel tubing.

Catalytic Converter

Catalytic converters (or cats) became common in the 1970’s, & since the 1980’s, car manufacturers are required by government regulations to fit all new passenger vehicles with a catalytic converter. The purpose of a cat is to reduce the toxic emissions (hydrocarbons, carbon monoxide, & nitrogen oxides) contained in the exhaust gas. It removes up to 90% of the toxins; reducing air pollution & making the exhaust emissions safer to people and the environment. The inside of a cat is coated with different combinations of metals such as platinum, palladium and rhodium. When the toxins come into contact with these metals, it causes a chemical reaction that turns these harmful toxins into nitrogen, water and carbon dioxide.

Signs there is a problem with your catalytic converter:

  • A lack of power.
  • Excessive heat coming up from the floor of your vehicle.
  • A sulphur smell (like rotten eggs).
These symptoms usually indicate that the cat is blocked.

Muffler

The muffler is sometimes also known as a silencer & is located near the rear of an exhaust system. The muffler’s function is to reduce excessive noise which is caused from the fuel combustion process. The muffler must meet the maximum acceptable noise level required by government regulations, while also allowing the exhaust to continue flowing smoothly. The muffler is a large round or oval chamber that uses materials to absorb noise. They also contain perforated tubes or chambers which cause the sound waves to bounce off of the back, front, & sides, creating opposing sound waves that cancel each other out.

Signs there is a problem with your muffler:

  • A significantly louder sound is the most noticeable sign the muffler is damaged.
  • Rust or holes. (If inspecting the muffler for physical damage, ensure you always let the exhaust pipe cool down first. Touching a hot exhaust pipe accidently can cause significant burns).

Exhaust Resonator

Some vehicles also have separate exhaust resonator located toward the front of the muffler, which are designed to  tune certain frequencies specifically for auditory appeal. Think a V8 engine’s ‘roar’.

Exhaust pipe

The exhaust pipe (or tailpipe as it is known in other countries) is located at the back of the vehicle beneath the rear bumper & is the exit point for the exhaust fumes. The side on which the exhaust pipe is located indicates the market, or country, for which it was intended. For example; European vehicles have the exhaust on the left (as they drive on the right, so the exhaust fumes are furthest from the curb). However; Japanese vehicles intended for countries that drive on the left; have the exhaust on the right side of the vehicle. Most vehicles have four-cylinder engines with a single exhaust but high performance vehicles like V8s will usually have twin exhausts.

Signs there is a problem with your exhaust pipe

  • A rattling sound from beneath the vehicle. This usually indicates a part has come loose or is dragging.
  • Rust or small holes.
  • Louder than usual exhaust sounds.
  • An unusual smell coming from the exhaust.

Service you can trust

If you notice any unusual symptoms with your exhaust system, or have any issues with your vehicle; contact one of our friendly, qualified technicians today on 0412 161 776 for a vehicle inspection. Don’t forget to like our Facebook page for handy hints, information and special offers.