Faulty spark plugs can cause various problems for a lawn mower’s performance. For example, your mower may not be able to start or won’t stay running. When this happens, you’ll want to replace the spark plug. But, before you do this, you’ll first need to know where is the spark plug on a lawn. Well, look no further. I’ll show you how to find a lawn mower spark plug, what it looks like, and how to install it. So, whether you have a push or a riding mower, I’ve got you covered.
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Where is a Lawn Mower Spark Plug? (Overview)
Lawn mowers typically have the spark plug located on a vertical part of the engine. Depending on the design of the lawn mower, the spark plug could be positioned on the front, back, or side of the engine. The spark plug connects to the engine between the cylinder head and the spark plug cable.
Are Lawn Mower Spark Plugs Always in the Same Place?
The spark plug location differs from engine to engine and mower to mower. However, the spark plug is always screwed into the cylinder head as this is where the spark from the spark plug is needed. Additionally, the cylinder head always sits towards the top of the engine regardless if the engine is horizontal or vertical. So you definitely don’t need to look under your lawn mower. Also, because a spark plug is a serviceable part of a lawn mower that needs regular inspection and replacement, the spark plug is usually in an easily accessible location. So, when trying to figure out where is a lawn mower spark plug, it will be pretty obvious once you know where to look.
What Does a Spark Plug Look Like?
A typical lawn mower spark plug is about 3 inches long and cylindrical. Half of the spark plug is made of metal, and the other half is made of white ceramic material. While the structure of a spark plug is pretty complicated, this gives you an idea of what to look for.
However, you won’t be able to see much of the spark plug once it is connected to the mower. So, when looking for the lawn mower spark plug, you’ll actually have to find the spark plug cable. What does a spark plug cable look like? Well, the spark plug cable is a small rubber/plastic cap that connects to the spark plug with a cable coming out of one end. Also, the spark plug cable and cap are nearly always black.
How Many Spark Plugs Does a Lawn Mower Have?
The number of cylinders determines the amount of spark plugs your mower has. For example, a push mower will have one spark plug, whereas a riding mower or a zero-turn mower could have two. This is because larger, more powerful lawnmowers typically have two cylinders and require two spark plugs. So, look at the engine and see how many spark plug cables you can find. If you find two cables, then you have two spark plugs. If you can only find one cable, then it’s likely you have a single-cylinder mower with just one spark plug.
Where is the Spark Plug On a Push Mower?
If you have a push lawn mower, you will want to look at the front of the engine. Typically, all push mowers have the spark plug at the front of the engine towards the top. So, head to the front of your lawn mower and look for the spark plug cable. Once you find the cable, you will have located the spark plug.
Where is the Spark Plug On a Riding Mower?
Mowers such as the Cub Cadet CC30 and Snapper Rider have the engine located at the rear of the mower. So, when looking for the spark plug on a riding mower, you’ll want to head to the back of the machine to the engine. Then using the same method as before, look for the spark plug cable in an easily accessible location. It’s unlikely that the spark plug will be at the front or on the sides of the engine as these are hard-to-reach places.
Where is the Spark Plug On a Tractor Mower?
You’ll need to look under the hood when locating the spark plug on a tractor lawn mower. Now because the hood of the tractor protects the engine from damage, the spark plug doesn’t need to be protected as the hood provides the protection. Therefore, the spark plug could be on any side of the engine. For example, a John Deere S100 lawn tractor has its single spark plug on the right-hand side next to the muffler. On the other hand, the Husqvarna YTH22V46 lawn tractor has its spark plug at the front of the engine above the OHV cover. So, hunt down the spark plug cable attached to the engine, and you’ll be able to locate the spark plug.
Where is the Spark Plug On a Zero-Turn Mower?
Now if you have a zero-turn, you likely have a twin-cylinder engine that requires two spark plugs. You will usually find one spark plug on one side of the engine and the second on the other. Again you can look for both spark plug cables to help find the spark plugs.
Are Lawn Mower Spark Plugs Universal?
After finding the spark plug, you’ll probably want to service or replace it. Now if you need to replace your spark plug, it needs to be specific to your lawn mower engine. This means lawn mower spark plugs are not universal. Even though many lawnmowers use the same spark plug, this doesn’t mean you can take a spark plug out of a Toro mower and put it into a Husquvarna mower. You’ll want to check the reference on the already installed spark plug or check in your owner’s manual. Also, some spark plugs are the same size but have different properties. So, even though a spark plug might fit in your mower, this doesn’t mean it is the right one.
For example, the table below shows three Briggs & Stratton push mowers that look pretty much the same. However, if you look at the part numbers, you’ll see that these three lawnmowers use three different spark plugs.
| MOWER MODEL | SPARK PLUG PART NUMBER |
|---|---|
| 22″ SMARTSTOW High Wheel Mower | Briggs & Stratton Part #692051 |
| 22″ Personal Pace Auto-Drive Mower | Briggs & Stratton Part #491055S |
| 21” Personal Pace Spin-Stop | Briggs & Stratton Part #594056 |
Symptoms of a Bad Spark Plug
If you’re trying to find your mower’s spark plug, it probably means you’re having engine problems. Here are a few symptoms you might face if your mower has a bad spark plug.
- Engine is hard to start
- Engine starts then dies
- It takes extra pulls of the pull cord to start the mower
- Mower struggles under power
- Engine sputters
- Engine backfires
How to Replace a Lawn Mower Spark Plug (The Steps)
After finding the spark plug, you need to test the spark plug to confirm it’s bad. After confirming your diagnosis, you’ll next need to install a replacement. Here are the steps and tools you’ll need.
Steps to Replace a Spark Plug
- Remove the spark plug cable.
- Using a socket wrench and an appropriate socket, remove the old spark plug.
- Set the old spark plug to one side.
- Thread the new spark plug into the cylinder head by hand.
- Tighten the spark plug into the engine using your socket wrench and socket.
- Once the spark plug is tight, give your socket a ¼ turn.
- Attach the spark plug cable to the new spark plug.
What You’ll Need To replace a Spark Plug
- Socket Wrench & Spark Plug Socket
- Replacement Spark Plug (Engine Specific)
