How to Remove Spark Plug from a Lawn Mower

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You should perform full maintenance on your lawn mower once every cutting season in order to keep it in optimal running shape. And changing the spark plug is one very important task you should be performing in the full maintenance of your lawn mower.

This guide is mainly focused on removing and changing your spark plug in a lawnmower, but you can also apply the basic steps to all 4-cycle gas powered machines like the chipper shredder or the pressure washer.

One of the major reasons why a lawnmower won’t start up is a worn out or faulty spark plug. The spark plug is responsible for igniting the repeated explosions inside the cylinder of a lawnmower’s engine. Due to its position (sitting inside the cylinder), it is subjected to extremely high heat, corrosion, and even wear.

When can you say a spark plug is faulty? Well, a spark plug becomes faulty when it no longer has the ability to generate a full spark, and as a result of this, you could face two problems.

  • The spark plug would not be able to produce enough spark to ignite the fuel in the chamber, which will in turn result to the lawnmower not being able to start up at all.
  • The spark plug will produce a below-par spark causing the explosion inside the chamber to become uneven. This can make the engine of your lawnmower rattle or vibrate and stall on some occasions.

On the bright side, replacing the spark plug in your lawnmower is an easy task and at the same time doesn’t cost much.

How to Check for a Faulty or Worn-Out Spark Plug

You need to figure out whether your spark plug is faulty before you think of removing and changing it. For your standard lawnmower and small engine maintenance, ensure that you check your spark plugs annually and also in accordance with the operator’s manual.

You should also check your spark plugs if your lawnmower refuses to start up. Here are the steps to check for a faulty spark plug;

  • First, you have to disconnect the spark plug lead. Then wipe the area around the spark plug in order to prevent debris from getting into the combustion chamber when you remove the plug.
  • Then you proceed to remove the spark plug with the use of a spark plug socket; this is to ensure that you remove it properly.
  • Now, check the spark plug thoroughly for very obstinate deposits, or for cracked porcelain or electrodes that might have been burned away. If you notice any of these conditions, then it is important that you change the spark plug to keep your lawnmower in perfect shape.
  • Inspect the spark plug gap and apply the necessary adjustments
  • If the spark plug seems fine, then place it back making sure not to tighten it too much, then re-attach the spark plug lead.

If the engine of your lawnmower tries to turn over before it dies, then the problem is most likely not associated with the spark plug, but if the engine doesn’t turn over, then your ignition system might be experiencing a fault. Your first course of action should be to change the spark plug.

How to Change the Spark Plug of a Lawnmower

In order to keep your lawnmower in optimal shape, you will need to get rid of all the faulty parts, like the spark plug, for example. Check out some of the Best Spark Plugs you can get to replace your faulty spark plug

  • Find the spark plug on the engine of your lawnmower. The location of the spark plug isn’t hard to find, because the wire that supplies electricity for the spark connects to the end.
  • Next, you have to remove the spark plug wire and unscrew the plug from the engine. Depending on the location of the plug you will need to use either a spark plug socket or a pair of channel locks. If the plug is embedded inside a hole, then you would need to utilize a spark plug socket to grip and remove it. On the other hand, a pair of channel locks would work perfectly if the plug is in a location that is easy to access.
  • You should have determined whether your spark plug is faulty using the steps mentioned above. Even if the spark plug is not faulty, it is advisable to replace it annually due to the fact that it is so easy and cheap, and it also helps to keep your lawnmower in top shape. But if the metal hook that is located above the pin looks solid and not corroded, then you might not need to change your plug.
  • Go to an online store and purchase a spark plug that is compatible with your lawnmower. Sometimes the manufacturers change the designations on the plugs, and occasionally various plugs can work with the same engine, despite the fact that the plugs don’t look entirely identical.
  • Proceed to gap the plug if needed. Gapping the plug is the process of making sure that the right gap exists between the sparking pin and the L-shaped bracket that covers the pin. Most plugs that are being manufactured now don’t need to be gapped because they are already “pre-gapped.” But if your plug needs to be gapped, then all you have to do is use a spark plug gap tool.
  • Next, insert the spark plug into your lawnmower, and then use your hand to tighten it, but not to tight. when you notice that there is significant resistance, stop tightening to prevent cross-threading. After you have successfully used your hand to tighten the spark plug, then you can proceed to use a pair of channel locks to tighten it in place.
  • Next, re-attach the spark plug wire, start the lawnmower and then the engine should start running smoothly.


Removing and changing the spark plug of your lawn mower is essential to ensure that the lawn mower stays in optimal condition. It is one of the simplest and cheapest ways to keep your mower running smooth for years to come. And it’s not a difficult job to do so be sure to check and if needed change yours at least once a season.