How To Clean a Spark Plug? (Easy 5 Step Guide)

Want to know how to clean a spark plug? We're about to make it easy!

In this guide, you'll learn:

  • What you need to know about cleaning a spark plug
  • Supplies you'll need for cleaning a spark plug
  • Steps you'll need to take to clean a spark plug

And much more!

How to Clean Spark Plugs

Your small engine or gas-powered vehicle needs healthy spark plugs to run at efficient and reliable speeds.

When your engine misfires, comes to a stop, or won't start in the first place one of the first actions to take in diagnosing the problem is cleaning the spark plugs. 

What if you remove a spark plug and the electrodes show signs of corrosion or carbon deposits? In a lot of cases, you may just want to replace the spark plug as a whole because it is a relatively cheap repair. 

In some cases, however, you can get away with simply cleaning the spark plug off and reinstalling it. 

A quick note before we start: If your spark plug is continuously fouling due to oil leakage or bad carburetor jetting, you are going to want to wait until you find the solution to the problem to install brand new spark plugs. 

Otherwise, you'll end up installing new spark plugs just to find them caked in oil and fouled again. That's why you may want to consider cleaning the old plugs up.

So, before you do clean your spark plugs, I recommend you read through this guide that will help remove the confusion that can occur from dealing with spark plug issues.

What You Need To Know About Cleaning a Spark Plug

Did your engine suddenly chug to a stop? Your spark plug may have fouled up. Diagnosing your spark plug problems can sometimes be frustrating, especially when the spark plugs keep fouling, and you can't figure out what the problem is. That's why we have created this page to help you get a better idea of the situation. 

Supplies You’ll Need For Cleaning a Spark Plug

The supplies you use to clean your spark plug will depend on where you are when your spark plugs need removal. 

For example, if you are in the dunes on your motorcycle with a fouled spark plug you might have to use a little bit of gasoline from the gas tank, some sand from the ground and the end of your shirt as a rag to get you back to camp (seriously, this could work). 

But chances are, you are working on a lawnmower in the comfort of your property. Wherever you are, servicing your spark plugs shouldn't be that difficult to do. 

Here's what you'll need:

  • A cleaning agent (brake cleaner, gasoline, alcohol)
  • Spark plug socket and socket wrench 
  • Torque wrench(for best installation results)
  • Feeler gauges or spark plug gap tool
  • Air hose(optional but useful)
Did you know: The gap on a spark plug and level of errosion directly effects your car's fuel efficiency. Cleaning the spark plugs can put more money back into your pocket!

How To Clean a Spark Plug (5 Step Guide)

  1. Remove the spark plug from the cylinder head
  2. Inspect the spark plug for fouling
  3. Clean plug with available cleaning tools
  4. Check spark plug gap
  5. Reinstall the plug and test the results

Step 1: Remove the spark plug

To remove the spark plug you will first have to remove either the spark plug wire or the coil pack using either your hands, a set of pliers or the appropriate socket.

After you have removed the high tension lead, use a spark plug socket or wrench to unscrew the spark plug from the cylinder head. Carefully remove the plug.

Step 2: Inspect the plug for fouling

Inspect the spark plug for signs of carbon buildup or blistering. If you see excessive carbon buildup, then that means there is too much fuel going into the fuel/air mixture.

If the tip of the spark plug looks burnt, this means there is a possible lean mixture of too much air and not enough fuel in the combustion chamber. 

Step 3: Clean plug with available cleaning tools

Use whatever you have available to clean the tip of the plug. You could use gasoline, brake cleaner, carb cleaner, seafoam or alcohol to wet the surface, and then use a wire brush, toothbrush, or sandpaper to clean off the metal electrode surface.

There are even spark plug cleaner machines that you can plug into the air hose if you want to be real fancy, but it's not necessary. After you have cleaned up the surface of both the center electrode and the side electrode, wipe it clean with a clean cloth.

Step 4: Check spark plug gap

Your spark plug could be misfiring if the electrode gap is not at the right measurement. Learn the gap specifications for your specific engine, and use feeler gauges or a gapper tool.

Step 5: Reinstall the plug and test the results

If you have access to compressed air, use the air hose to blow out any residue or debris from the cylinder. This will help to Then reinstall the clean spark plug and torque to spec if you have a torque wrench.

If you don't have a torque wrench, be sure to tighten the plug firm but not over tight. Don't forget to apply some dielectric grease to the inside of the spark plug boot before installing to create the best electric connection possible.

Read More >> How to Gap a Spark Plug

Other Valuable Resources on Cleaning Spark Plugs

(Tips for Avoiding a Fouled Spark Plug)

The best ways to avoid a malfunctioning spark plug are keeping your air filter clean, your carburetor jetted correctly, and oil leaks to a minimum. 

If you are noticing excess fuel consumption from your small engine, try adjusting the carburetor to a more lean mixture to allow a cleaner-burning fuel/air ratio into the combustion chamber. This will keep your spark plug from fouling. 

You must also consider that not all spark plugs will come back to life once they have fouled. Sometimes the best option is to purchase a new plug for the best results. Just be sure your engine is running efficiently and properly before you do to avoid fouling a brand new plug.

Now you have a little bit more knowledge about cleaning a spark plug. Don't get discouraged if you follow all of these steps and the engine fails to start, or continues to run poorly.

The solution is there, sometimes you just have to dig deep to find the cause of the problem. 

Read More >> How to Remove a Broken Spark Plug

About Your Mechanic

About Ryan Nichols

Ryan here! My pro mechanic career began as a technician for Mercedes-Benz. After two years of that great experience, I went out on my own in both the automotive and construction fields. I've since pulled my share of salvage yard parts and fixed more vehicles than I can count.

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