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Spark plugs are crucial components in most outdoor power equipment, including your lawn mower.

Part of proper equipment maintenance is checking and cleaning the different components, from the air filter to the spark plug.

How to clean a spark plug on a lawn mower? You can use a Q-tip dipped in rubbing alcohol or a little WD-40. Make sure the plug is dry before reinstalling it.

Keep your mower functioning properly so you’re ready for mowing season! A little elbow grease now can save you a headache down the line.


What is a Spark Plug in a Lawn Mower?

Mechanical components of a gas lawn mower. Foam filter, starter or spark plug and choke lever in the carburetor of the thermal engine

The spark plug is part of your lawn mower’s engine that’s responsible for ignition. It’s located inside the engine’s combustion chamber.

What do spark plugs do? The mechanism has two exposed “heads” or tips, and a central electrode that connects to the terminal through a spark plug wire.

When a high voltage current goes through the plug, the current “jumps” between the two heads and produces a spark. That ignites the mixture of gas and air inside the engine, powering the mower.


Why Clean Spark Plugs?

Dirt on the spark plug – whether that’s from overfilled engine oil or general wear and tear – prevents it from igniting the fuel properly.

This can lead to increased fuel consumption, inefficient engine performance, or even more emissions.

Moreover, dirty spark plugs can affect engine health. Your engine could misfire and dirt could get into the cylinders.


Signs to Clean Your Lawn Mower Spark Plug

The biggest sign of a dirty spark plug is an engine that won’t start. If your lawn mower starts then dies, or if it won’t start at all, the spark plug is the likely culprit.

Should your lawn mower start, a dirty spark plug will cause erratic engine performance. You’ll hear your lawn mower engine “struggling” – either sputtering or accelerating noisily.

Check in with your regular lawn mowing service about the state of your mower as well!


How to Check Your Lawn Mower’s Spark Plug

checking of spark plug of a lawn mower

Check your owner’s manual for the location of the spark plug. Most lawn mowers have them around the back or side of the engine. It’ll look like a short cylinder sticking out.

Make sure the lawn mower is switched off (unplug if needed) and completely cooled down.

Detach the wire from the plug, then use your fingers or a wrench to remove the spark plug.

Check the tips of the plug – they should be metallic grey or tan. If there’s any oily residue, baked-on soot, or other dirt, it needs cleaning.


How to Clean a Lawn Mower Spark Plug

Again, start by switching off the lawn mower and letting it cool down completely.

Detach the wire, ideally using a wire puller so you don’t damage the insulation.

Remove the spark plug from its housing using a socket or plug wrench. Check for any damage, such as cracked insulation or corroded electrodes.

If the spark plug is just dirty, not damaged, you can safely clean it. 

To clean spark plugs, use a Q-tip dipped in rubbing alcohol (or your chosen spark plug cleaner) to remove any soot and grease off the tips.

Then take a soft wire brush and clean the threads, sides, and housing. Avoid using more abrasive methods such as sandpaper.

For more stubborn dirt, WD-40 is a great spark plug cleaner. Make sure to wipe off any excess product afterwards.

Ensure both the plug and housing are dry before reassembling. Reinstall the spark plug then reattach the wire.

Try and start the lawn mower to ensure everything’s been reconnected properly.


gasoline-powered self-propelled lawn mower


How Long Does a Lawn Mower Spark Plug Last?

The best practice is to change a lawn mower spark plug every 25–30 operating hours.

However, if you notice signs of wear (such as scratches or breaks), it’s best to get a new spark plug immediately.

The maximum lifetime of a spark plug is 2 years, with or without use.


How to Change a Spark Plug

These days, spark plugs are affordable, so it’s not always necessary to clean and reuse them. Regardless of condition, though, it’s best to change to a new plug after 25–30 operating hours.

Check your old spark plug for a model code so you can buy an identical one from the shop. If you can’t find the code, you can look up your lawn mower’s model online or ask in the shop.

It’s optional but recommended to apply some anti-seize compound onto the threads of your new spark plug. This makes it easier to remove the next time.

Position the spark plug and thread it into its housing. Use your spark plug wrench to tighten it one additional three-quarter turn.

About Author

Jamie Donovan

Jamie is an Australian horticulturalist and landscape designer. He enjoys writing about landscape architecture, garden design and lifestyle topics.


About Author

Jamie Donovan

Jamie is an Australian horticulturalist and landscape designer. He enjoys writing about landscape architecture, garden design and lifestyle topics.