How Long Do Lawn Mower Spark Plugs Last?

You can immediately consult the owner’s manual for your lawnmower to determine how long the spark plug lasts.

If not, lawnmower spark plugs are good for a season’s worth of use or, in some cases, 25 to 30 hours (maximum).

Indeed, spark plugs are an essential part of a lawnmower. These small devices assist in igniting the fuel-and-air mixture within the combustion chamber of the mower. It is done to ensure that the engine has sufficient power to start. 

Why Replace Your Spark Plugs

Spark plugs are not intended to last the life of a lawnmower. They deteriorate over time as the electrode tip becomes shorter and blunter with each spark.

If the spark plug is bad, the mower may run poorly or not start.

Here are some advantages to replacing your spark plugs:

1. Smooth Starts – Hearing the first time you turn on the ignition with a new spark plug can be very refreshing. You won’t have to pull the starter rope several times before the engine starts.
2. Fuel Efficiency– New plugs can improve fuel efficiency and save you money on fuel.
3. Optimum Combustion– A fully operational spark plug will create a more operational combustion process.

Checking, Cleaning and Replacing Lawn Mower Spark Plug

The video demonstrates how to inspect, clean, and replace your lawn mower spark plug in three simple steps.

It provides a brief but comprehensive guide on how to do it. The quick guide for inspecting, cleaning, and replacing your spark plug is as follows:

Step 1: Inspect Spark Plug

It would help if you inspected the spark plug, which begins with removing the spark plug.

1. Remove spark plug wire– you can grip the wire, pull it straight off of the spark plug, and then move it out of the way.
2. Remove the spark plug with a wrench– place the wrench over the spark plug until it engages.
3. Begin turning– once settled, you can begin turning the wrench until the spark plug comes loose.

Step 2: Clean Spark Plug

Once the spark plug is removed from the engine, you will see that your spark plug is covered with carbon. You can restore it by cleaning it.

1. Prepare a soft-wired brush– begin brushing the outside edge of the spark plug, turning it as you go until it is clean.
2. Check spark plug gap– insert the spark plug gapping tool on the smallest end of the spark plug.

If you successfully restored, cleaned, and checked the gap on your spark plug, you could reinstall it in your lawnmower.

Step 3: Replace Spark Plug

If you have determined that your spark plug is damaged, you should consider replacing it with a new one.

You should also consult your engine operator’s manual for replacement guides, as not all spark plugs will work with your lawnmower engine. 

Frequently Asked Questions

Should I reuse the spark plugs on my lawnmower?

You can, but there’s a good reason why you shouldn’t. Spark plugs can also fail electrically, and oil and carbon deposits create an alternate electrical path.

So, even if a used plug has been meticulously cleaned, it can still malfunction under load, failing to provide an optimal spark inside the engine.

How to determine if a spark plug is bad?

If the engine tries to start but then dies, you most likely have a bad spark plug. It would imply that your ignition system isn’t working properly.

The first step is to change out the spark plug.

Can a bad spark plug cause a mower to stall?

Yes, because a bad spark plug frequently causes a cylinder in an engine to misfire. While mowing, the engine may even completely shut down.

You may also notice that restarting becomes more difficult each time the mower dies.