Cheshire Oaks Service Station - Phone 0151 356 4757

For a competitive quote on Exhaust Systems and Component repair in Ellesmere Port, please call on 0151 356 4757 or email us here with you vehicle details.

What do the Exhaust Systems and Components do?

Exhausts have four main functions: to control noise, to direct exhaust fumes away from passengers, to improve the performance of the engine and to improve fuel consumption.

The tailpipe is the part of the exhaust that you can see extending from the back of the car.  The silencer joins onto the tailpipe, and then a series of further pipes joins the silencer to the catalytic converter and then the engine.

Exhausts can corrode from both the inside and outside. How long your exhaust lasts for depends on how far and how often you drive your car rather than the length of time it has been fitted.  Vehicles used for short trips around town tend to corrode their exhausts in a much shorter time and distance than cars used predominately for long journey.

It’s only when you hear or drive a car with a damaged silencer that you realise what a huge difference it makes to reducing noise levels, and the way a silencer works is quite fascinating.  It contains a deceptively simple set of tubes that are finely tuned to reflect the sound waves produced by an engine so that they cancel each other out.  If there is a hole in the silencer then the sound waves are no longer forced through the tubes and escape outside – increasing the noise level.

The exhaust manifold acts as a funnel.  It collects exhaust gases from all cylinders of the engine then releases them through a single opening, often referred to as the front pipe.  The exhaust centre section works with the silencer to reduce noise and the tail pipe at the rear carries gases away from the vehicle.  All of the components of an exhaust system are connected with a series of clamps, hangers, flanges and gaskets.

Why is a healthy exhaust system so important?
Your exhaust system is the only means of carrying away those noxious fumes, like the environmentally destructive gas carbon monoxide, generated by your engine.  An exhaust that has failed can lead to noxious fumes being drawn into the vehicle cabin and prolonged exposure to exhaust fumes can make a vehicle occupant feel drowsy, which could lead to an even greater danger.  A healthy exhaust system is critical if you are to maintain the health and welfare of the vehicle occupants, a quiet smooth running engine and optimum fuel efficiency.

How can I tell if my exhaust needs attention?

The noise your exhaust makes can tell you a lot about its general condition, if you notice any of the following you should have your exhaust checked by us to find out whether any components need replacing;

The silencer is the part of the exhaust that usually needs attention first, as it is the furthest away from the engine and is the most likely to be corroded by acidic moisture.  This is because these parts remain relatively cold and give exhaust gases a chance to condense and form pools of corrosive acid inside the system.


  • Rattling – a rattling noise may indicate loose brackets or clamps holding the system in place
  • Roaring – a roaring noise could be a potential problem with the silencer
  • Hissing– this could be a sign that the silencer, gasket or one of the pipes is leaking
  • Chugging-this could be a sign that one of the silencers could be blocked

Visual appearance

  • Rust or corrosion on the pipe as well as cracks, especially where the pipes connect could indicate a problem
  • Rust or corrosion on the silencer or hangers as well as loose outer skin would have a affect of the parts becoming insecure

Catalyst converters are an integral part of a car’s engine management system, not simply a part of the exhaust system.

What Does My CAT Do?

  • Catalytic converters are designed to reduce:
  • Carbon Monoxide (A colourless and odourless poisonous gas)
  • Hydrocarbons or Volatile Organic Compounds (A major component of smog, produced mostly from evaporated unburned fuel)
  • Nitrogen Oxides (NO and NO2 (combined called NOx) which contribute to smog and acid rain causing irritation to human mucus membranes.)

So the oxygen sensor, catalytic converter and ECU all work together to help to achieve the lowest possible output of dangerous and polluting gases.

How A CAT Works

When gases are emitted from the exhaust chamber, they pass into the exhaust system.  A lambda sensor measures and adjusts the air / fuel ratio and stops un-burnt fuel reaching the CAT directly.  When the gases reach the CAT they are exposed to a coating of precious metals which act as a catalyst on these gases, converting them from harmful to safe fumes.

All modern petrol car exhausts manufactured from 1993 include a catalytic converter.  This reduces harmful emissions of hydrocarbons, carbon monoxide and nitrogen oxides into the atmosphere.  Catalytic converters are so efficient that the difference in emission readings for cars with converters and those without are huge.

Main Causes of CAT Failure

Carbon Pollution

As a direct result of too rich fuel mixture and/or oil or antifreeze entering the exhaust system, deposits build up on the internal monolith, leading to a partial or complete blockage.

This blockage or partial blockage can have the following effects:

Carbon deposits can reduce the surface area which allows the thermal reaction to take place.  If these carbon deposits are allowed to continue over an extended period, eventually all will become blocked and you might notice a reduction in the performance of the vehicle. If the vehicle is used with the monolith blocked the catalyst might become noisy.  This is a direct result of the exhaust gases seeking an alternative route of escape and destroying the substrate, which separates the monolith from the stainless steel casing.  This renders the catalyst completely inactive.

Converter Meltdown

If neat fuel enters the exhaust system, the fuel will ‘superheat’ the catalyst and the monolith might be partially or totally destroyed. This may block the exhaust or just be burnt and blown out of the system.

A catalyst suffering this type of failure is easily recognized.  The converter glows red in operation, or is externally discoloured by the effects of the extreme heat the catalyst has experienced.

Common causes of failure are:

  • Lack of servicing
  • Some catalysts contain ceramic bricks which can break if they suffer a knock
  • Engine misfire or bump starting a vehicle
  • Leaded fuel can poison the catalyst
  • Leakage of welds or pipes can change the air / fuel ratio
  • Sudden cooling of the catalyst ie. Driving through deep water.

Another device that helps to reduce carbon emissions is the oxygen or lambda sensor and transmits information to the engine management system or electronic control unit (ECU).

The lambda / Oxygen sensor measures and sends oxygen content information back to the engine management system (ECU).  This monitors the percentage of oxygen present in exhaust gases which makes second by second adjustments to the fuel and air mix being used by the engine.  This makes sure that harmful gases are burnt efficiently in the catalytic converter.  If the lambda sensor becomes faulty, the engine management system sends a default amount of fuel to the chamber – it’s as if you are driving with the ‘choke out’.  You may be using more fuel than necessary and might notice your car is not running as smoothly

The ECU (Electronic Control Unit) — using information obtained from the oxygen sensor — constantly adjusts the air/fuel mixture so that the cleanest and most efficient combustion is achieved under all operating conditions.  Sometimes, a ‘failed’ catalytic converter can be due to a fault in the engine management system.  In these circumstances a new catalytic converter may not rectify the problem.

So the oxygen sensor, catalytic converter and ECU all work together to help to achieve the lowest possible output of dangerous and polluting gases.