Lawn Mower Air Filters: Everything you need to know

Whether your mower runs on a two-stroke or four-stroke engine, it will require an air filter… and overtime all lawn mower air filters need cleaning.

As the name suggests, they air filters are the first defense for an engine against dirty, dust, and any debris of whatever size, and so they are responsible for the good functioning and overall health of your engine.

When you buy a lawn mower for the first time, it will have an air filter fitted – which you should confirm before use – but over time it becomes worn and too dirty that you will need to change it.

If you do not replace or clean the filter, your mower will be exposed to all those engine hazards the same way it would if it didn’t have the filter altogether.

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What are these air filters made of?

Most of them are made of paper and synthetic fibers that are quite effective in trapping the smallest of particles. They catch up to 99% of contaminants while also stopping particles of size 5-6 microns – or larger – from sneaking in to your engine.

image of a mower's air filter

How an Air Filter Affects your Lawn Mower?

You could buy a mower without a filter, then proceed to use it without checking. If you only use it in one session then note and make the right changes, then you can salvage your engine.

Not much damage will have been done, and so you won’t ruin it. If you use your mower continually without an air filter, then a few things are likely to happen.

1. Internal Engine Damage

Every time your mower runs, it allows in air that goes straight to the engine. If it not filtered, then all the dust particles and debris will make their way there, pooling heavily so that the engine finally succumbs to internal damage.

If you fail to replace a dirty filter or insert one, then you could eventually have to replace the entire engine, which is costly. Note: Your mower’s engine will not fail all at once.

The process will be slow as it will be unable to draw enough air to cool it properly, and the symptoms will unfold over time.

2. Mower Loses its Effectiveness

Some people complain of their mowers not working at their full potential after some times, which would include it slowing down after sometime or failing to start as fast as it did when it was brand new.

It could also go off without warning right in the middle of mowing. Most people rush to change the oil as it would have some debris floating, but the real cause is usually the lack of a filter.

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An oil change will not kick it back to its previous performance, and so the most important thing would be to replace or put in a filter.

3. Excessive Fuel Consumption

When a full tank would previously last an entire mowing session, it reduces to half the time now, even though the terrain is the same. If this happens to you, you might want to check the state of your air filter.

When to Replace a Filter         

For effective use, you want to change a filter after 25 hours of use or at least once a year.

If it is made of paper, then go ahead and replace it completely, but if it is made of foam you can wash it with hot water and soap, wring, and reuse it.

When returning it after washing, you want to saturate it in oil and then wring it out because a filter is supposed to be oily, not merely clogged with oil.

air filter image

Note that an air filter clogged with oil is preventing your mower from working as effectively as it should, and in it makes no sense having it there.

Before you turn over your mower to work on your blades, engine oil leaks out and fills up the filter, necessitating replacement or change.

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Final Word On Lawn Mower Air Filters

Over time, an air filter will get clogged with oil, but you can prevent it from happening before its time.  When turning your mower to check on blades or the deck, you want to turn the air filter side up.

If this isn’t possible, then ensure the gasoline has run out and then siphon the oil before turning your mower. This prevents any chances of leakages and spillages that could clog your filter and cost you more.