Common exhaust issues and how to spot them

Kwik Fit | Tuesday 16th September 2014 10:00am

Exhaust on floor

Your exhaust emissions system is the only means of channeling away noxious gases like carbon monoxide and nitrogen oxide that are generated by your engine. If your exhaust system fails, fumes could enter the vehicle cabin and prolonged exposure can be damaging to your health. Under existing regulations the Police can warrant the removal of any vehicle from the roadways on the suspicion that it is producing excessive amounts of pollutant gases from the exhaust.

A healthy exhaust system will also provide:

  • optimum fuel efficiency
  • improved engine performance
  • noise control and quieter running

Therefore, it is important to ensure your exhaust is working to the best of its ability. Identifying a problem with your exhaust system is fairly easy – just use your eyes and your ears…

How to spot an exhaust problem

Many exhaust problems can be identified with a visual check. Examine the entire length of the exhaust from the engine all the way down to the tailpipe and look for any cracks or holes, especially where one section meets the next e.g. the seams and joins between the exhaust manifold and the cylinder. External rust may not be as serious as it first appears, because it may only be on the surface. However if the component has rusted through or is rusted from the inside (due to internal condensation build up) it may be a cause for concern. Use a screwdriver to gently prod rusty areas; if the structural integrity feels weak or a hole is formed, it is a sure sign that this section of the exhaust needs to be replaced.

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 journeys. This is because the exhaust system doesn’t reach the temperature required to burn off accumulated water on these shorter trips.

Listen for the signs – a noisy exhaust is a damaged exhaust

Listen out for unusual sounds coming from your exhaust system. A noisy exhaust or an exhaust that is making strange sounds is a sure way to detect a problem.

The silencer is the part of the exhaust that usually needs attention first, as it most likely to become corroded by acidic moisture. If you have a problem with your silencer you will know about it as your exhaust will begin to make a loud roaring noise. This just goes to show how effective a working silencer is at removing noise from the exhaust system. Other noises to listen out for include hissing, which indicates a crack in the exhaust manifold, exhaust pipe or a leaking gasket. A chugging noise could mean a blockage in the exhaust system.

If you hear rattling under the car it could mean that the exhaust system has become misaligned while a loud metallic vibration usually means that something is touching the exhaust pipe or that a clamp, support bracket or mounting is loose. Hangers and brackets hold your exhaust in place. Corroded, fractured or missing brackets and hangars can cause extra stress on the system which can also lead to premature exhaust failure.

Your exhaust might not be the problem

Should your exhaust begin to produce smoke, this probably isn’t a sign of a problem with the exhaust system but rather an issue with the engine. Black exhaust smoke means that your engine is burning fuel too quickly. If this occurs check your air filter, fuel injectors and the fuel pressure regulator. On the other hand, if you see white smoke coming from the exhaust, it may be nothing to worry about. It could simply be a build up of condensation in the exhaust system. However, if the exhaust continues to emit white smoke for an extended period of time, this suggests your engine is burning coolant and you may have a problem with your cylinder head or have a cracked head gasket. If coolant is leaking into your engine oil it will appeared discoloured and creamy.

If in doubt we’ll check it for free

Don’t risk failing your MOT, or worse still, put your health at risk. If you have any concerns regarding the health of your vehicles exhaust system, our trained technicians can provide a free exhaust and emissions check at over 600 centres across the UK.

We’ll check your exhaust and catalytic converter for cracks, leaking joints, broken hangers, worn rubber mountings, corrosion, failed gaskets and high levels of pollutant gasses and will discuss and provide guidance on any areas that do not meet safety requirements. Book a no obligation exhaust inspection at Kwik Fit and receive a 15% discount should any work be required.

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