Quite simply put, 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 your engine.
So how can you detect if your air filter is dirty?
Power Loss - An air filter covered in dirt and oil will suffocate 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.
Increase Fuel Consumption - If your not getting as much run time out of your engine as usual, it may be because your air filter is dirty. 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 engine will stall, surge, and sputter as it gasps for air.
If your air filter is damaged or has a hole in it, you risk harmful debris entering the carburetor and damaging your engine.
So what do you think is cheaper, rebuilding/replacing the engine or changing a dirty air filter? Go with the air filter.
So when do I clean or replace my air filter?
Air filters can be cleaned if the entire component is still intact, with no tears or holes in the air filter fibers.
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.
Air filters can be changed easily. Read your owner’s manual for any specific air filter replacement recommendations.
So protect your engine and clean or replace your air filter.