Checking Air Filters - Mick's Tips of The Trade

By: Mick McCrudden

Presented by

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Changed the air filter in your car lately? Mick says it's crucial

Air filters have changed hugely over the past 100 years. If you go back to FJ Holden days, 60-something years ago, you’d open up the engine bay and come across something called an oil bath air filter.

Basically they were an oil bath where the air would get drawn through the fluid, the particles would get caught, and clean air went into the carburetor.

As we’ve moved on, we’ve mostly gone for pleated paper filters with different shapes and micron ratings If you look at the photo of the two white filters, the one that’s gone grey is only six months old, so about 10,000km. That gives you an idea of how much dirt and pollution they’re picking up. You imagine trying to breathe when you get a cold – that’s what it’s like for the car. The downside is the engine is working harder to do the same thing, using more fuel and its hurting your economy.

With a modern car, you know when you pull up behind and get that bad sulphurous smell? It’s because it’s running rich and the cat isn’t coping. With older cars, you pull up behind and there’s a big cloud of black smoke as they take off.

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People will do silly things like pulling out injectors and cleaning them, or try getting into the tuning via the computer when – nine times out of 10 – it’s just the air filter.

It’s a very simple system, but it’s essential it’s changed regularly. I would suggest every six months, if you’re using the car daily. As the example of the two white filters show, it doesn’t take long for things to block up.

When it comes to quality, you get what you pay for. With the really cheap filters, you’re problem is the risk they start to break up and feed bits of filter through your fuel system. It’s not catastrophic, but it’s a hassle you could live without.

When it comes to modifying the air filter, think of your engine as giant pump. If it’s able to draw in more air and fuel mixture, it should perform better.

In a lot of situations, a cold air induction system works a treat. We’ve all had that experience where the car feels better on a cool evening, drawing in that cool dense air. Done right they work. They’re an expense, so you need to weigh up whether it’s worth it.

If you’re going that way, it’s advisable to check what it’s doing to the mixture. So you put a ‘sniffer’ up the exhaust before to get a base reading (assuming it’s right when you start!) and then check it once the modifications are done.

A lot of workshops have the gear and it doesn’t hurt to seek an opinion. It will vary from one car to another. For example a lot of fuel injections systems are self-monitoring and can adjust on the run.

Anyway, just remember to check your air filter. You might be surprised at the difference it makes. It’s people who don’t check them who keep me employed!

Mick owns Glenlyon Motors, an expert workshop and car storage facility in Brunswick, Melbourne. Call him on (03) 9380 5082.


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