How to clean a spark plug on a lawn mower is the knowledge you cannot live without. Having clean lawn mower spark plugs that are in perfect condition is essential for keeping the engine running and functional.

Clean Lawn Mower Spark Plug

This article will go through each cleaning step, from taking the plug out to putting it back in.

Find out the various methods you can employ to eliminate all that grime that eventually builds up on the plug’s surface over time in this tell-all guide.

How To Clean A Spark Plug on a Lawn Mower Easily?

To clean a spark plug on a lawn mower easily you should gather your supplies, clean the area around the plus, and take it out. Inspect it first, and clean the dirt thoroughly; then you should fix the gap in the plug and lastly, place the clean plug back. 

To clean a mower engine spark plug, you must take it out using a plug socket wrench and lay it on paper. Clean it and place it back afterward if it is still in good working condition. This is a necessary step to accomplish because the clean tool will boost the functionality and better power to the machine to run on.

– Gather All Your Supplies 

A spark plug socket wrench is a must-have; otherwise, the plug won’t come out. For cleaning purposes, brake cleaners or wd40 are some basic items. For stubbornly stuck grime and corrosion products, you might need help from sandpaper, a wired brush, or a blow torch, and when you have these supplies the task will be accomplished faster. 

Of course, clean rags or paper towels are a must for any cleaning endeavor so that the mess would be make clean after. You can do without insulated pliers, but it helps to have them around. Make sure to borrow a gap measuring tool to check the plug’s efficiency while it is out for cleaning. Lastly, wear a pair of insulated rubber gloves during work for your protection from any harm that would come. 

– Clean The Area Around The Plug

Turn the engine off first because you do not want to get an electric shock while cleaning a lawn mower spark plug. Allow the engine to cool fully before touching the mower again, because this way you would be taking some cautiousness regarding any sort of electrocution to take place, this will help in the process of the machine’s full neutral state.

Cleaning Area Around the Plug

In most mowers, spark plugs are located behind the air filter, which needs to be removed first to gain access to the chamber housing the plug. But after doing so, remember that you will need to unscrew the nuts and bolts holding the air filter shroud in place. 

It is important to clean the area surrounding the plug first. Otherwise, the dirt and debris might fall into the engine, and this, in turn, could end up clogging the engine badly. Take any good engine cleaner and use a clean cloth to wipe off all the dirt and grime around the plug area, and make sure that you would also remove anything that would be stuck to the plug, you can use a toothpick and clear it out. 

– Take The Plug Out First

Notice the spark plug wire connecting it to the engine and pulling at it. It takes a little controlled force and wiggling to disconnect it from the engine. Next, take a spark plug wrench and fix it on the base. 

Use this wrench to loosen the plug until it starts rotating freely, that is when you know the matter is quite safe to do so. Afterward, from loosening it well, the matter becomes easy to remove it with your hands. Trying to pull the plug out using any ordinary wrench is a mistake because this method will not only not work but might also damage the plug.

– Inspect It Carefully

Place the plug on a paper towel and examine it from all sides, and the most important part is to look at the plug’s tip inside the combustion chamber of all lawn mowers. One can accurately diagnose the engine’s condition by looking at the plug tip. Which means that if this tip is gray in color and dry, then your engine is in good working condition, and there is no need to worry at all. 

On the other hand, if you notice that this tip is wet with oily droplets, the engine burns too much oil and needs a little less oil than you give it. Also remember that if the small engine is two-stroke, you need to switch to a fuel with a lower oil quantity. Sometimes, the deposits on the plug tip are black-colored and foamy, and this indicates that more oil is required and one that is less enriched; knowing this trick would save you a good amount of time.

Inspecting Spark Plug Carefully

At the same time, you must also look for signs of physical damage to the spark plug. Always replace spark plugs with new ones once they get damaged. See if the spark plug gap is normal or if it needs to be fixed; ideally, the distance should be between 0.02 and 0.035 inches. This is the distance between the side and the central electrodes of the plug; remember that you should adjust the matter accordingly, to have a proper inspection.

– Clean Dirty Spark Plug

You might be curious about how to clean spark plugs with wd40. You can get a spark plug cleaner from any well-stocked home store. Another option is to go for a brake cleaner which is more aptly available in auto and mechanic shops. It would be best to get these cleaners in spray to attack the grimiest spots easily.

Allow these spray cleaners to stay on the plug for two to three minutes, as specified by the manufacturer. The latter is the approximate time needed to break down built-up grime and corrosion products. Afterward, you can take any clean cloth and wipe everything down, to have a clear plug and make sure that no dirt would stick to it; you may have to leave it for a very short time to air dry, if the towel or wipe was a bit damp. 

The tip is the most important part of the plug that needs cleaning regularly. What you must do is hold the plug firmly as you clean the top with the other hand; as a result, you will see that the rest of the plug gets dirty less often.

Sometimes, cleaning spark plugs becomes more complicated because of corrosion products and extremely stubborn pieces of dirt. In this case, you can get some 220-grit sand, which will help get rid of corrosion from the plug easily. Just keep rubbing it in a back-and-forth motion until the clean metal starts to show from the surface of the plug, and there you have it.

Making sure that you would reach and get the space between the threads of the plug can be a tricky part to clean thoroughly because this step will make matters quite easy regarding the functionality. On another note, you may also purchase a wire brush and use it first in the direction of the threads and then in the opposite direction for a thorough cleanup. Just don’t forget to wear gloves while you are using a wired brush to save yourself from accidental poking, and hurting yourself in any way possible.

A metallic file is another alternative that can help clean all the otherwise inaccessible corners of the spark plug. Don’t forget that you can also use some alcohol, which is a DIY plug-cleaning product that you apply to the tip and other dirty parts for one to two minutes, you can do so by placing some on the cloth and rubbing it well. However, be sure that during this time, it softens the grime, which is then scrubbed using a soft brush that can be either plastic or brass. 

– Correct The Gap In The Plug

Now, you must adjust the gap, so what you need to do is to take out the gap measuring tool to see if there have been any unwanted increases or decreases in its gap. For most plugs, the ideal gap is somewhere between 0.02 and 0.035 inches, but again, this may vary from one mower to another mower. This is why it is essential that you would aim to check out the manufacturer’s guidelines to see what the gap of your plug needs.

Clean the Gap in Spark Plug

After measuring the gap, you can either fix it yourself or take help from a nearby mechanic if you do not wish to do it on your own. In short, correcting this gap is important so that the perfect spark is created while igniting the engine.

– Put The Clean Plug Back

Now that the plug has been cleaned thoroughly, insert it back into the engine. What you can do is use your hand and try to thread it inside by a simple and gentle rotation. Then, you can use some adjustment or help from the spark plug socket wrench to tighten it carefully. 

After you have done so, reinsert the plug back from where you removed it from. Test start the engine to see if the plug is working correctly or not. If your plug was encased by a shroud, metal covering, or filter frame, then screw these back in place, and you have accomplished a great job. 


Taking a spark plug out and cleaning it does not seem so much hard work after you have read this article, and now you know the easiest approach.

Here are the quick points of what we just covered:

  • Clean the dirt around the plug even before taking it out for proper cleaning.
  • Once the plug is out, you can do simple cleaning using brake cleaners, rubbing alcohol, or any other appropriate grime-cleaning product.
  • If built-up corrosion products are on the plug, use sandpaper to rub them off.
  • Take this opportunity to inspect the plug for any visible signs of damage and measure the gap responsible for producing the right spark.

Using our easy-to-follow guide above, you can carry out the most effective spark plug cleaning operation annually, as the manufacturers recommend.

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