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Do It Yourself - Outdoor Power Equipment Repair & Maintenance

Dirty Air Filters are Engine Killers

What Do Air Filters Do?

This isn't a trick question. The purpose of an Air Filter is to filter the air.

Air must be clean before it mixes with the fuel and burns in the cylinders of an engine.

Unfiltered air contains all sorts of dirt and debris. Think of all the grass and dirt that flies around as you mow your lawn. You certainly wouldn't want any of those particles to enter the internal parts of your engine.

So what are some symptoms you can detect if your air filter is too dirty?

Symptoms of a Dirty Air Filter

Dirty Air Filter Covered in Oil and Dirt A lawn mower air filter covered in oil and dirt.

Power Loss

Dirty air filter = decreased airflow = less power

A clogged air filter covered in oil and dirt will smother your engine, not allowing the proper amount of air to burn with the fuel. Less combustion power means less horsepower. If you notice your mower is not maintaining consistent power, check your air filter.

More Fuel Consumption

If you're not getting as much run time out of your equipment as normal, it may be the dirty air filter that's causing your engine to consume more fuel.

Your engine is trying to compensate for the loss of performance by burning more fuel.

Starting Trouble

Air, Fuel, and Spark. Without one of these components your engine will never start.

So, if your air filter isn't providing the right amount of air flow into the mixture, your equipment will stall, surge, and sputter as it gasps for air.

Damaging Effects of a Worn Out Air Filter

Hole in Air Filter Holes in the air filter allow harmful debris to enter the carburetor.

Dirty air filters can lead to worn out air filters. Holes in the fibrous material or cracks around the edges of the filter may form, allowing the dirt and debris to enter the parts of your engine.

If your engine is exposed to these debris particles, it will cause premature wear to the internal parts of your engine, including the pistons, cylinders, and carburetor.

So what do you think is cheaper, rebuilding/replacing the engine or changing a dirty air filter? Go with the air filter.

When to Clean/Replace Your Air Filter

Dirty vs. New Air Filter Dirty Vs. New Air Filter Comparison

Clean: Air filters can be cleaned if the entire component is still intact, with no tears or holes in the air filter fibers.

Replace: If your air filter is covered in oil, the fibrous filter material is torn, or there are cracks around the filter, you should replace it.

Replacing your air filter is a job you can easily do yourself, instead of taking it into a repair shop. Read your owner's manual for any specific air filter replacement recommendations.

So protect your lawn mower, chainsaw, generator, trimmer and any other power equipment from an Engine Killer. Clean or Replace that dirty air filter!


Jack's Safety Tips: Before servicing or repairing any power equipment, disconnect the spark plug and battery cables. Remember to wear appropriate safety glasses and gloves to protect against harmful chemicals and debris. View our Disclaimer.