What is a vehicle exhaust system?

The exhaust system is a series of interconnected sections made of pipes and boxes that runs from the engine all the way to the pipe you see at the back of your vehicle.

Modern exhaust sections are most commonly made form aluminised steel, as its lightweight, strong and corrosion resistant. However, high-end exhaust sections can also be manufactured from stainless steel, while exhaust manifolds are sometimes made from cast iron to better withstand the heat that is transferred from the engine.

These different sections are commonly known by slightly different names, depending on the exact strcuture of a particular exhaust system, but typically an exhaust system comprises of;

  • An exhaust manifold - The exhaust manifold can sometimes be part of a larger front-pipe section, and sometimes also include the Catalytic Convertor (CAT). The Manifold is the exhaust section which bolts directly onto the engine, so is fitted with a gasket to ensure a continuous tight connection.
  • A Front-pipe - The front pipe often incorporates flexible section made from braided steel that isolates the manifolds connection to the engine from the movement of the rest of the exhaust system, which is suspected on rubber hangers and allowed to flex along with the vehicle. The exhaust front-pipe can sometimes also include the Catalytic Convertor (CAT).
  • A catalytic convertor (CAT) - The catalytic convertor reduces harmful gases, including carbon monoxide by passing the exhaust gases over and through a catalyst made from precious metals such as platinum, which causes a chemical reaction, breaking down the polluting gases into less harmful ones. One diesel vehicles, the Catalytic convertor is sometimes integrated into a diesel particulate filter (DPF), making it look like a single box/filter.
  • A Middle-section - The exhaust middle section often incorporates a box known as a silencer, or muffler in the US market. The purpose of the silencer, as the name suggests is to absorb sounds waves to reduce noise pollution. However, on some vehicles where sound is less of an issue, the exhaust middle-section is a simple tube/pipe section
  • A Back-box and tail-pipe - The back-box is the final section of the vehicle exhaust system, and the only part that most people will ever see. In all but a few rare cases, this sections always incorporates a silencer box and will have one or two tail pipes out of the back that release the now cleaned vehicle exhaust emissions into the atmosphere. At an increased cost, replacement exhaust back-boxes can sometimes be fitted with chrome plated tail pipes. If the back-box on your car need replacing, and this is something you would like, remember to discuss this with the management team at one of our branches.

What does the Exhaust system work?

The primary functions of the exhaust are to direct exhaust emissions away from the vehicle, and to reduce, or muffle, engine noise.

However, in more recent years, exhaust systems have taken on the additional roles of filtering noxious fumes and exhaust particulate matter generated by your engine, to keep the environment cleaner, while maintaining the performance of your engine and fuel efficiency.

This is not an easy balance to maintain, requiring the exhaust system to be continuously monitored by the vehicles engine management system. As such, even the smallest of pin holes in certain exhaust sections can cause problems.

Vehicle exhaust system have sensors within certain sections, which monitor the mixture of exhaust gases. If these gases fall outside of expected tolerances, possibly due to leakage, the engine management system will compensate to rebalance these gases by increasing or reducing fuel injection. The knock effect of this could be increased fuel consumption, reduced power and, may even bring a light on the dashboard.

In diesel vehicles, there are additional sensors which monitor exhaust gas pressure within the exhaust system. These pressure sensors look for pressure differences across the diesel particulate filter to determine if the filter is becoming blocked and required the vehicle to initiate an automated cleaning process known as DPF regeneration. Constant short journeys can prevent these regeneration process from completing, which can lead to a blocked DPF w=that can only be fixed by a technician using a diagnostic tool to perform a forced DPF regeneration.

Exhaust problems can be serious, so if you do notice any signs that it is not performing effectively, please call us as soon as possible, or book a free exhaust check.