What Spark Plug to Use for Lawn Mower?

Do you ever feel, Lawn mowing is a tedious job? And if the engine of your lawn mowing machine keeps cutting off because of its outdated spark plug, it becomes more disturbing. In such a case, changing spark plug should be the to-do thing. Now questions may arise regarding – what spark plug to use for lawn mower?

Well, worry not because we have got you covered. This piece of writing will guide you- how to choose right spark plug and will address a few other queries relating to choosing lawn mower spark plugs.

Identifying the Bad Spark Plugs- First Thing First

You may be wondering how to know if it is time to change the spark plug. When the plug of your engine goes bad, you will face different kinds of issues with running the machine.

Let’s know about some mostly faced symptoms so that you know whether or not the problem is with your spark plug.

  • Difficulty With Starting The Engine

This is the most commonly occurred problem when the spark plug is bad. The land mower gets harder than normal to start.

If it’s a push mower, then it will require more pulls than necessary, and if it’s a lawn tractor, then turning the key once won’t start the engine. This happens when the spark created by the plug is too weak to ignite the fuel.

  • Engine Performing Poorly

Even after you have managed to start the engine, it will cut off after a while. You will have to crank the engine again, which will be more difficult now because of the heat produced.

The expansion caused by heat, in the gap between the plug’s center and firing electrodes, will weaken the ignition.

  • Excessive Fuel Consumption

On top of those, if your engine starts consuming fuel more than normal, then be sure of what to blame. Plug creating weak sparks messes up with the fuel burn and increases the consumption. If you notice that the engine is out of fuel more frequently than necessary, your poor plug might be the culprit.

  • Error In The Physical Appearance

Detach your spark plug and perform a check to see if it has an error. The center electrode of the plug should have its top flat. If you find that to be round, then the plug needs replacement. Furthermore, any kind of damage to the body will require replacement of the spark plug.

What Spark Plug to Use for Lawn Mower? (Right One)

This is easier than you think. But one thing you need to remember is that spark plugs for lawn mower are different from those of automobiles. The key differences are that the size and length in the thread of sparks plugs are greater in an automobile than in lawnmower. So, make sure you don’t confuse between the types.

Get The Best Self-Propelled Electric Lawn Mowers

Spark plugs used in lawnmowers can be differentiated by factors like their sizes, heat range, and gap. You will have to ensure that the plug fits your engine’s gap and is able to be attached tightly. Follow these easy steps to find out the perfect one.

Match with Your Old Spark Plug


Disconnect the spark plug wire along with the rubber cap. Then use a spark plug wrench to twist and detach your old plug from the engine. You may write the part number. Then take the plug to the store and buy a new one matching with that.

Check Your Manual

If you somehow do not have the old plug, no worries. You can also read the manual that came along with your lawnmower.

Instructions on what type of spark plug you can use should be found there. If not, just learn about the model of the lawnmower or the engine. Take the details to the store; they will help you find it out for you.

Check It Yourself With Gap Checker

You can also take a new plug and check its gap using a spark plug gap checker. Most of the spark plug’s gap is 0.030 inches, while some being less or more, like 0.040 inches.

You can also adjust the gap yourself using the gap opener in that checker. Find the one that matches your required gap, and you’re good to go.

How to Check If Spark Plugs Are Firing or Not?

You might sometimes want to check the ignition spark of your plug to see if it’s going well. There are spark plug testers that you can use.

Disconnect the ignition coil from the spark plug, then connect the tester in between the coil and the plug. Now, rest it aside and crank your engine.

Check if your plug is sparking. If your plug is flashing with a small light, it is sparking. And if there is no fire at all, then your plug is not sparking. You can also check it by using a screwdriver on the ignition coil.

Checking spark fire in clear view. Let’s watch a video-How it looks like?

How Often to Change Spark Plug?

It depends on your usage to decide how often you should replace the spark plug. Most of the people change their spark plug once a year, and it is recommendable to do so.

You can also keep your plug for two straight years if the rate of your usage is not so high. As long as it functions well, you can keep it.

How to Clean a Spark Plugs – Right Way!

After long use, you will find dark soot over the plug made from carbon. It is better off to clean that up.

The recommended way of cleaning a spark plug is wire brush to rub over it and to use plug cleaner spray, which is specifically made for cleaning of the ignition area.

However, keep in mind that you should never use shot blaster or abrasives to clean spark plug, ever!

Lawn Mower Spark Plug lifespan – How Long it Goes? 

A regular lawn mower spark plug can serve you up to two years or more, depending on your usage. It is advisable that you clean the plug regularly to have it last longer.

Sometimes the engine may not work properly because of the dark clog or oil smeared over the plug. In this case, you don’t have to change the plug at all. Just clean it and reattach, your engine will work fine!

To conclude:

That’s all for now. We hope, now you know exactly What Spark Plug to Use for Lawn Mower?  And know, How you overcome inconvenience from your Lawn Mower.

Furthermore, We are happy to see you in the comments. If you have any question or something else wants to know.

Mt Shawn

Mitchel Shawn was a Co-worker and Engineer of a Gardening Tool manufacturing company since 2013 and a passionate researcher on Machinery goods. Picking the right tools for your work-station and making life easier is an untold helping journey by SHAWN. With this Reviewer Guides Blog, you’ll definitely get help in revealing the accurate product spec which actually helps in real life works.

We will be happy to hear your thoughts

Leave a reply