removed air filter placed on top of lawn mower-ft

A Simple Guide to Cleaning Your Lawn Mower’s Air Filter

Your lawn mower may be one of the biggest and most expensive tools in your garden shed, so it’s important to keep it clean, healthy, and running smoothly. Learning how to maintain your lawn mower is a simple thing, especially since, in most cases, all you have to do is take it in for a service, and the service center will sort it all out for you! However, there are some small things you can do at home to keep your trusty mower in good condition between doctor’s visits, such as cleaning or replacing the air filter.

The air filter is a very important part of your lawn mower, which sits between the carburetor and the engine, and stops dust, dirt, and debris from moving into the engine’s combustion chamber, and clogging it up. If this air filter becomes very dirty, or if it tears, it can no longer properly protect your lawn mower’s engine from the damage done by excess dirt and dust. In this case, engine performance will be decreased, along with the lifespan and durability of the engine, causing you to need to invest in a new lawn mower sooner than you had hoped.

Foam Air Filters and Dual Element Air Filters

There are generally two types of air filters used in lawn mowers – foam air filters and dual element air filters.

Foam filters are one single line of defense, and dual filters have a foam pre-filter, backed by a paper filter to catch anything that makes it through the foam. Please be sure to read your lawn mower’s user manual to find out which type of filter your lawn mower contains.

Pro tip: Reusable air filters should be cleaned after every 25 hours of use, and replaced after 300 hours of use.

Foam air filters generally come in two types – disposable and reusable. Disposable filters should never be cleaned and reused, but should always be replaced when dirty. In this article, we will be discussing the cleaning of reusable air filters.

Pro tip: You should avoid using any solvent-based cleaning agents when cleaning your air filters, and despite some popular advice, never use an air compressor to clean your filters, as it may cause holes and tears.

When to Clean and When to Replace Your Air Filters

Before you begin, you should be aware of how to tell whether your air filter is worth cleaning, or if it should rather be replaced.

For paper filters, the easiest way to know if it is worth cleaning is to remove it from the lawn mower (as described below), tap it gently on a floor or wall to release the dirt, and inspect it under good light. If most of the light is blocked out, even after tapping the filter to remove the dirt, it is time to replace your filter – check your user manual for the correct type of filter, and purchase and install a new one.

For the foam filter, look for yellow stains and crumbling sections of foam. If either of these can be detected, buy and install a new filter.

Related: How To Change Lawn Mower Oil And Which Oil To Use

Things You’ll Need

You will need the following to begin, depending on the type of filter you will be cleaning:

  • Safety gloves (foam filters)
  • Water (foam filters)
  • Liquid soap (foam filters)
  • Paper towel (foam filters)
  • Motor oil (foam filters)
  • Cleaning brush (dual filters)
  • Vacuum cleaner (paper filters)

Cleaning a Reusable Foam Air Filter

  1. Place your lawn mower on a flat, convenient work surface, such as a cement floor.
  2. Put the mower in parking mode, and be sure to let it completely cool down if it has been in use.
  3. Once the mower is cool, either remove the power cable from the battery, or disconnect the spark plug.
  4. Find the cover or shroud for the filter housing, and remove it (consult your user manual if you are not sure where this is located).
  5. Remove the foam air filter, and rinse it with water.
  6. Apply liquid soap to the filter, and clean off old grease and dirt. Be gentle with the filter.
  7. Once it is clean, dry the filter well with paper towel, and then leave it in the sun to dry for at least an hour.
  8. Once the filter is bone dry, apply a small amount of motor oil to it on both sides (this will help to catch dirt and dust). Motor oil can be lightly sprayed on, or carefully massaged on with your fingers. One to two teaspoons of oil will be enough – be careful not to apply too much, as it will drip into the machine, and cause black smoke to be released on engine start, and could damage the filter. If you feel that you have applied too much motor oil, simply remove the excess with a paper towel.
  9. Replace the filter and close the housing, being sure to carefully tighten any bolts that were removed when opening the machine.
  10. Reconnect the power cable or spark plug, and deactivate parking mode. Your mower is now ready to use.
air filter on a lawn mower
Unscrewed air filter housing.
air filter on top of the lawn mower
Air filters get dirty with debris and oil.
disassembled lawn mower air filter
Disassembled housing of the air filter.

Cleaning a Dual Element Air Filter

Please check your user manual for manufacturer instructions before cleaning your dual element air filter. If cleaning is not advised, please rather replace the filter, as you could cause damage to the engine by trying to clean the filter. Many manufacturers do not recommend cleaning your paper air filters, as they are fragile, and it is easy to damage the cell structure. Should your user manual recommend cleaning, follow the steps below to do so:

Follow steps 1 to 4, as listed under “Cleaning a Reusable Foam Air Filter,” then continue as follows:

  1. Separate the foam and paper filters, and follow the instructions above for cleaning a reusable foam air filter.
  2. While the foam filter is drying, concentrate on the paper filter. Tap the filter out against a wall or floor, which should remove most of the dirt and debris.
  3. Hold the paper filter up towards a bright light, and inspect it for areas that may still be full of dirt.
  4. The easiest way to clean a paper air filter is with a vacuum cleaner. Focus your efforts on those areas which show dirt when held up to a light. If you should tear the filter by accident, do not try to reuse it – rather get a replacement before using your lawn mower again.
  5. Before reinstalling the filters, clean the air filter compartment of your lawn mower with a clean brush – do not try to blow it out with an air compressor, as this will force dirt further into the machine.
  6. Apply motor oil to the foam filter, and replace both filters in the housing, being careful not to allow the paper and foam filters to touch, as the motor oil will damage the paper filter.
  7. Replace the filter housing cover, screwing it on tightly. Reconnect the battery or spark plug, and disengage park. Your lawn mower is ready to use.
Here’s a great video on how to clean various types of air filters found on small engines.

Now you know how to clean your lawn mower’s air filter, get out there, do this quick and easy job, and get back to having fun while mowing your lawn on a beautiful sunny day. Your garden will look beautiful again, and it will all be worth it.