How to Clean a Lawn Mower Air Filter

Take proper care of your mower's first line of defense

Lawn mower
Mint Images / Tim Pannell
Project Overview
  • Working Time: 15 mins
  • Total Time: 1 hr, 15 mins
  • Skill Level: Beginner

Having a properly functioning air filter is a gas-powered lawn mower's first line of defense against the dirt and debris that is kicked up during the mowing process. When the air filter is in good condition and working properly, it prevents dirt from entering the engine through the carburetor. But if the air filter is worn out, dirt and other debris can make their way into the engine, leading to potential start-up problems and a shorter engine life.

How Often to Clean a Lawn Mower Air Filter 

Cleaning or replacing the air filter is simple lawn mower maintenance that will improve performance and extend the life of your mower. Clean the foam pre-cleaner every 25 operating hours. Replace the paper air filter once per season or after 300 hours of operation. In dusty conditions, more frequent cleaning and replacement may be necessary.

Tip

Look for an air filter that fits your model mower, and always check the owner's manual to see what's recommended. There are three types of air filters on the market: a foam air filter requiring oiling to coat the foam; a paper filter that looks like accordion folds in a plastic casing; and a hybrid, or dual-element, filter that includes both a foam element (called a pre-filter or pre-cleaner) and a paper element as the main filter.

What You'll Need

Equipment / Tools

  • Safety gloves
  • Wash bin, wash sink, or garden hose
  • Clean, dry rags, cloths, or paper towels

Materials

  • Replacement filter (if necessary)
  • 1 to 2 teaspoon engine oil for foam filter
  • Liquid dish detergent

Instructions

  1. Stop the Mower

    Stop the mower's engine. Wait for all moving parts to fully stop and cool down before handling.

    Warning

    Do not operate the mower without an air filter as serious engine damage can occur.

  2. Disconnect the Spark Plug

    Disconnect the spark plug wire before removing the cover to the air filter.

  3. Remove the Shroud to the Air Filter

    Remove the screws or undo the clips that secure the lawn mower's protective shroud (covering) over the air filter.

    A lawn mower's air filter is usually located near the top of the engine and is encased within a metal or plastic shroud that is usually secured by a screw or with snap fittings.

  4. Remove the Air Filter

    Remove the air filter, and inspect it.

    For a paper filter, gently tap it on a flat surface to remove any loose dirt. Examine the filter, and hold it up to a bright light source. If the filter's paper element blocks a significant amount of light, then it's time to replace it, but don't try to clean it further. Simply replace it with a new one.

    If you have a foam air filter, look for signs of crumbling or telltale brown or yellow staining, which indicates it's time to replace it. If it's still in good shape, you can proceed to clean it.

    If you have a hybrid air filter, follow the manufacturer's instructions on how to clean it or when to replace it. A hybrid has a foam pre-cleaner that needs to be inspected. If the foam pre-cleaner has become stiff, brittle, or significantly stained, it usually needs to be replaced.

  5. Clean the Foam Filter

    Wash the foam filter in a wash sink or bin or with a garden hose to thoroughly clean out the dirt. Use dish detergent to cut the grease and help remove dirt. Rinse the foam of soap thoroughly, and squeeze out excess water with paper towels, cloths, or your hands.

  6. Dry the Foam Filter

    Before oiling the foam filter, thoroughly dry it. First squeeze the foam with paper towels or dry cloths. Then sit the foam in the sun for about an hour to further dry.

  7. Oil the Foam Filter

    After the foam is bone dry, oil it. Put oil in your hands or directly on the foam, and massage it through the filter to distribute it well. Be sure not to add excess oil because you do not want it dripping into the mower.

    Tip

    An alternative way to add oil is to put the foam in a plastic bag or baggie, add oil, and massage the bag to saturate the foam with the oil. Blot up excess oil by patting the foam with a clean paper towel.

  8. Clean the Air Filter's Fitting

    Before reinserting an air filter, clean the air filter's housing with a dry cloth. Do not use solvents, as they can damage the air filter element. And do not use compressed air, which could force debris down the throat of the lawn mower's carburetor.

  9. Reinsert the Air Filter

    Replace the air filter into the fitting. Make sure it fits well and there are no gaps.

  10. Replace the Shroud

    Reattach the protective shroud, being careful not to pinch or otherwise damage the air filter element in the process.

    Warning

    Never force the shroud back into place. If it does not reassemble easily, you've probably inserted the new filter element incorrectly.

  11. Reconnect the Spark Plug

    Don't forget to reconnect the spark plug wire so you can start your mower.