How a car’s air filter works
A car’s air filter stops dust, debris and pollen from entering your engine, helping it to run cleanly and efficiently. Modern fuel-efficient engines are hi-tech pieces of kit that mix precise ratios of air and fuel to achieve optimum performance and economy. This places increasing demands on filters to supply clean air to the combustion chamber.
The latest air filters claim to block up to 96 per cent of debris, and most are made of a paper-type fibre with accordion pleats that increase their surface area to trap as much debris as possible.
Air filters may be hidden away inside a housing, but checking and replacing them if necessary is one of the easiest and cheapest car maintenance tasks that can be done.
And it’s money well spent, because a clean air filter can prolong the life of your car’s engine.
How a dirty air filter can cause engine problems
Whether your car is petrol or diesel, one fact remains – it needs air. Both fuels have to mix with oxygen in order to be at their operational best. Without air, your engine will cough, splutter and die.
But it has to be clean air. It’s sucked deep into the combustion chamber of your engine, so it has to be free of debris. If not, that debris will damage your engine, usually irreparably.
Of course, the car makers have thought of this, which is why you’ll be confronted by a big black plastic box under the bonnet of every car. In this box sits the air filter, which collects all the dust, dirt and grit lingering in the atmosphere, stopping it from playing havoc with your engine’s internals. But how long do these filters last?
In theory, you could leave the same air filter in your car for years. However, if you do leave it too long, you’re going to find the filter gets so clogged it doesn’t let enough air through. As such, you really should change your air filter once every two or three years at a minimum.
Changing it is easy and cheap, with most filters being about a tenner, while the costliest ones can about twenty quid. You normally have to contend with nothing more than a few spring clips, take the old one out, put the new one in, job done. It’s that simple.
If you live in a city, you may need to change your filter more frequently. Take a picture of your new filter for reference, then compare it after six months of use, if it looks significantly darker/dirtier, fit a new one.
The other option would be to upgrade the filter. You can buy performance air filters that are a direct fit replacement for the originals. These filters will let a bit more air through, while still keeping dirt and debris at bay. They can help with performance and in some cases, they can be washed/cleaned out and re-oiled, making them as good as new.