26 October 2002: Drivers should get their exhausts checked regularly, to avoid causing themselves and other road users serious problems, warns Tenneco Automotive, producer of the Walker aftermarket exhaust system products.

A damaged or worn-out exhaust can lead to excessive vehicle noise, toxic gasses entering the car, higher levels of pollution outside the vehicle, higher fuel consumption, sluggish acceleration and reduced engine performance.

If an exhaust component actually falls off while the vehicle is travelling along, it then becomes a major hazard. The car’s driver could be in danger if he or she stops to pick it up off the road, while other road users will be at risk as they either swerve to avoid hitting the fallen exhaust – which can cause an accident – or drive over the component – which could cause a tyre to blow-out.

It’s easy for a driver to spot a broken tail pipe hanging underneath their car or if the vehicle emits dense, choking fumes, but not every exhaust-related problem is quite so obvious. When a catalytic converter isn’t working as well as it should, for example, harmful waste products are released invisibly into the atmosphere. However, Walker advises that a quick and inexpensive check at a garage or exhaust centre would soon reveal if there was a problem.

Exhausts mainly wear out because of corrosion or breakage. Internal corrosion is caused by the condensation of exhaust gasses after the car has stopped and cooled down. This is a particular problem on short distances, where the car has not time to warm up and expel acid gasses and condensates that build up.

External corrosion is caused by wet climates or in winter conditions where salt is used on roads. In some countries with extremes of wet or wintery weather, external corrosion can be the most common cause of exhaust damage.

Exhaust parts can break if damaged by the vehicle being driven over very rough terrain, or if the exhaust components have not been properly fitted – which puts them under greater stress – or if the engine vibrates excessively, which again subjects the exhaust to greater stresses. Another common problem is caused when motorists fail to fit new exhaust mounting components when replacing a muffler.

Catalytic converters can become contaminated (usually if leaded fuel is used by mistake), or the monolith, the core of the converter, can literally melt down if it comes into contact with unburned fuel, which can occasionally happen when the car is run on empty, push or tow-started, or has a defect in the ignition or carburation system. In addition, the lambda sensor, the device which controls the air/fuel mix, may have failed, causing the ‘cat’ to operate inefficiently.