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Can You Run A Lawn Mower Without An Air Filter? Should You?

Written by Steve
Last Updated on July 19, 2021

Do I Need An Air Filter For My Lawnmower?

I like tinkering with things, it’s a man thing I think (Gents, back me up on this one). This has led me to strip down many lawnmowers over the years so I happen to know a thing or two about how they work. 

Lawnmowers should not be used without air filters. Mowing the lawn causes dirt, grass, and debris to go in all sorts of places and one place you don’t want it to go is the engine of your lawnmower. This is why an air filter is important. 

Without it, you run the risk of damaging your mower. 

I’m sure you may have heard about someone using their lawnmower without an air filter and it didn’t do any harm but below I’ll explain what damage it could do to your engine and what’s actually happening when you’re not using an air filter...it’s pretty interesting! 

Is The Air Filter Important On A Lawnmower?

Yes!

Air that goes into lawnmowers is cleaned by the air filters. Much in the same way they ensure, it’s clean air that goes into your car or your vacuum.

An air filter is designed to prevent any dirt, grass, or unwanted particles from getting into the engine, which could ultimately damage the engine. 

As part of any lawnmower, the cooling system needs clean air to function properly. 

If you have a petrol-driven lawnmower, then an air filter is arguably more important. It will help to combust fuel and power the engine. 

If a filter isn’t present, this can lead to a damaged engine due to debris getting into it. However, it also means that the ratio of air to fuel is all wrong with a petrol engine. 

These issue will affect how the lawnmower functions and not for the best! 

[Is your lawnmower overheating? Read this.]

Why Do Some People Use A Lawnmower With An Air Filter?

Sometimes people will use a lawnmower without a filter - rightly or wrongly! So let’s look at situations when that might happen. 

  1. The Air Filter Is Missing - Alright, so, some people will lose the air filters, and rather than replacing them, they will use their mowers without one for months and report no or little damage. 

I am not recommending this in the slightest as at any point you could find something enter your engine and damage it beyond repair. 

It wouldn’t take a lot, let’s say even a tiny stone to enter the engine and destroy an essential part such as the carburetor. 

Yes, it could be repairable but quite often it isn’t and for the cost of an air filter, you could save yourself a lot of money down the line and hassle! 

[Have you got white smoke coming from your lawnmower? Take a look at this]

  1. Lawnmower Isn’t Starting With The Air Filter In Place - This is more likely to be the case with petrol lawnmowers. You may find that when you remove the air filter, the mower will start but it won’t start when it’s in place.

Why is that?

Honestly, it’s just down to the fact that the air filter is most likely going to be clogged - time to clean it!

If your air filter is dirty, the air is not going to be able to make its way to the engine. Meaning that no combustion will happen and so the engine won’t start.

The engine not starting could also be a sign that there is damage to the air filter or not installed correctly (or the gasket could be faulty).

Whilst removing the air filter will resolve the issue, it’s not something to see as a permanent solution. 

Cleaning, replacing, or repairing the filter so that your lawnmower can operate exactly how it’s intended is the right answer! It’s the only answer frankly.

  1. When You Need To Diagnose The Faults On A Lawnmower - If you feel like your lawnmower isn’t running as it should, removing the air filter is often a good way to run a diagnostic test on it.

Again, this is only a very short-term thing to assess what the fault is. If your lawnmower is still not performing as it should, then it’s likely that the fault is somewhere else in the machine. 

At this point, you should replace the air filter and continue finding out the issue. 

The Importance Of Air Filter MaintenanceTo Your Lawnmower (And You!)

If your air filter is damaged or dirty, then it’s almost as bad as not using one. 

Your engine will not be able to breathe as it should as the air circulation won’t be operating correctly. 

Using a dirty or worn-out air filter can actually result in dangerous debris getting into the engine. 

There are several things you need to do to maintain your lawnmower and cleaning your air filter (and occasionally replacing it) is one of those things.

Using the right type of filter is important too - there are different types - three of them to be exact!

You can get foam air filters. In order to trap particles, these filters need oil. 

Then you have paper filters and dual filters. These both have paper and foam components. 

Depending on which type of air filter you have, will determine how you should care for it. My advice is to read the owner’s manual as this will give you tailored advice.

If you continue to use your lawnmower with a dirty air filter, it won’t run efficiently and you’re going to get poor performance, essentially meaning that you’re going to be working harder to get the right type of cut you want.

[What lawnmower will give you the best cut? Find out here!]

It will also mean that your lawnmower will be more difficult to start and won’t have the power you’re used to. This is down to the fact that the engine won’t have access to the required airflow and combustion will be less. 

In order to compensate for this lack in performance, the mower will use more fuel so it’s going to cost you more in running costs too. 

A lawnmower without an air filter will also run in a similar way, have trouble starting, and lack power. 

Combustion won’t be able to occur efficiently because there will be more air than fuel in the engine.

Is It Expensive To Run Your Lawnmower Without An Air Filter?

As we’ve discussed, lawnmowers can run without an air filter but that doesn’t mean they should. It’s likely to cause damage. 

When you’re trying to diagnose a fault with a lawnmower, it should be fine to run the mower without a filter for a short while and that’s all it needs to be. 

For all other times, you really should be using an air filter!

If you lose or damage your filter, replace it. If it’s dirty, clean it (or treat yourself to a new one).

The good news is that air filters aren’t an expensive part of the mower and they’re easy to look after too! 

Using an air filter means that you could be potentially saving yourself from the greater expense of replacing your engine or lawnmower - now that makes sense, doesn’t it?

[How often should you service your lawnmower?]

Final Thoughts

So yes, lawnmowers can function without an air filter but they are not designed to and shouldn’t unless for very specific reasons. 

When was the last time you looked at your filter?

About the author
Written by Steve
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