Is your lawnmower refusing to start? Before you call for expensive repairs, the first thing to check is the spark plug. Learning how to remove lawnmower spark plug is a simple skill that can save you time and money. This guide will walk you through the entire process safely and efficiently, even if you’ve never picked up a wrench before.
A faulty spark plug is one of the most common reasons for a mower’s engine troubles. It might be fouled with carbon, worn out, or simply gapped incorrectly. By removing and inspecting it, you can diagnose problems, clean it, or replace it with a new one. The job takes only a few minutes and requires basic tools you probably already have.
Let’s get your mower running smoothly again.
Remove Lawnmower Spark Plug
Before we start with the steps, it’s crucial to gather what you need and prioritize safety. Working on small engines is straightforward, but a few precautions will prevent accidents and ensure you don’t damage your equipment.
Tools and Safety Gear You’ll Need
You won’t need a fancy toolbox for this job. Here’s what to collect:
* Spark Plug Socket: This is essential. It’s a deep socket with a rubber insert inside that grips the spark plug to prevent damage and makes removal easy. Sizes are typically 5/8″ or 13/16″.
* Socket Wrench or Ratchet: To turn the spark plug socket.
* Extension Bar (Optional): Helpful if the spark plug is deep in the engine cowling.
* New Spark Plug: It’s a good idea to have a replacement ready. Check your mower’s manual for the correct type and gap.
* Safety Glasses: Always protect your eyes from any debris.
* Work Gloves: To protect your hands and improve grip.
* A Small Wire Brush or Cloth: For cleaning around the plug area.
* Spark Plug Gap Tool: If you’re installing a new plug, you’ll need this to check the electrode gap.
Critical Safety Steps Before You Begin
Never skip these steps. Your safety is the most important part of this guide.
First, ensure the mower is completely cool. A hot engine can cause severe burns. Wait at least 30 minutes after the last use.
Next, disconnect the spark plug wire. This is the single most important safety step. Pull the boot (the rubber cap) firmly off the end of the spark plug. This ensures the engine cannot accidentally start while you are working on it, even if the pull cord is tugged.
Finally, clear your work area. Work on a flat, stable surface like a bench or patio. Make sure you have good lighting so you can see what you’re doing.
Step-by-Step Removal Process
Now, let’s locate and remove the plug. Follow these numbered steps closely.
1. Locate the Spark Plug. Find the spark plug wire you disconnected. It is attached to a thick, short wire. Follow that wire to the engine. The spark plug is a porcelain or ceramic cylinder (usually white) with a hexagonal metal base, screwed into the engine cylinder head.
2. Clean the Area. Use your small brush or cloth to wipe away any grass clippings, dirt, or debris from around the base of the spark plug. This prevents anything from falling into the open engine cylinder once the plug is out, which could cause serious damage.
3. Remove the Spark Plug Boot. Double-check that the rubber boot is completely disconnected and pushed safely out of the way. Sometimes it can snap back, so rest it somewhere where it won’t interfere.
4. Fit the Socket. Place your spark plug socket directly over the spark plug. Ensure it’s fully seated on the hexagonal metal part. If you have an extension bar, attach it to the socket now.
5. Loosen the Plug. Attach your ratchet or wrench to the socket or extension. Turn it counterclockwise (lefty-loosey) to break the plug’s seal. It may be tight initially. Apply steady pressure until it loosens. If it’s extremely tight, avoid forcing it; a bit of penetrating oil applied carefully around the base can help.
6. Unscrew by Hand. Once the plug is loose, you can finish unscrewing it by hand. Carefully turn the socket with your fingers until the spark plug is completely free. The rubber insert in the socket should hold the plug, allowing you to lift it out.
7. Inspect the Removed Plug. With the plug out, take a moment to look at it. A healthy plug will have a light tan or gray coating on the electrode. Signs of trouble include heavy black carbon (sooty), wet oil residue, or a white, blistered electrode. This inspection can tell you a lot about your engine’s health.
What to Do After Removal
You’ve successfully completed the remove lawnmower spark plug task. Now you have a few options depending on what you found.
If the plug looks reasonably clean and you just wanted to check it, you can choose to reinstall it. However, spark plugs are inexpensive, and for the reliable performance, installing a new one is often the best choice.
If you are installing a new plug, you must check the gap. The gap is the space between the center and side electrode. Take your gap tool and find the correct specification for your mower model (often printed on the mower or in the manual). Slide the tool between the electrodes; the correct feeler gauge should slide through with a slight drag. Gently bend the side electrode to adjust if needed.
To install, simply reverse the removal process. Carefully thread the new (or cleaned) plug into the hole by hand first. This is vital to avoid cross-threading, which can strip the engine’s threads. Once it’s hand-tight, use your socket wrench to tighten it a final quarter to half turn. Do not overtighten.
Finally, press the rubber spark plug boot firmly onto the end of the new plug until you feel or hear it click into place. You should now be ready to test your mower.
Troubleshooting Common Removal Problems
Sometimes, things don’t go perfectly smoothly. Here’s how to handle common issues.
* The Spark Plug is Stuck: If it won’t budge, don’t brute force it. Apply a few drops of penetrating oil around the base and let it soak for 15-30 minutes. Try again with steady pressure. Using a longer breaker bar can provide more leverage, but be very cautious.
* The Plug is Rounded Off: If the hexagonal edges are stripped, a standard socket will just spin. You may need a specialized stripped bolt remover socket set.
* Debris Fell in the Hole: If anything fell into the cylinder, do not turn the engine over. Use a straw or flexible magnet tool to carefully retreive the debris. Compressed air can also help, but use it gently.
* The Threads are Damaged: If the plug feels loose or won’t tighten properly, the cylinder head threads may be stripped. This requires a more advanced repair called a helicoil insert, which you might want a professional to handle.
FAQs About Spark Plug Removal
How often should I remove and check my lawnmower spark plug?
You should check it at least once per mowing season, ideally at the spring tune-up. Replace it annually for best engine performance and fuel efficiency. If your mower is hard to start or runs roughly, check the plug first.
Can I clean and reuse an old spark plug?
Yes, you can clean a lightly fouled plug with a wire brush and some brake cleaner. However, for the cost of a few dollars, a new plug guarantees a strong spark and is usually the better option. A worn electrode can’t be fixed by cleaning.
What if I don’t have a spark plug socket?
A deep well socket of the correct size can work in a pinch, but you risk cracking the porcelain insulator. The rubber insert in a proper spark plug socket is there for a reason—it protects the plug and holds it for easier installation. It’s a worthwile investment.
How tight should the new spark plug be?
Hand-tight plus a quarter to a half turn with the wrench is standard for most small engines. Overtightening can crack the insulator or damage threads, while under-tightening can lead to poor compression and overheating. If your new plug comes with a crush washer, tighten until the washer compresses and you feel firm resistance.
Why is my new spark plug black after just one use?
A sooty black plug often indicates a too-rich fuel mixture (too much gas, not enough air). This could be caused by a dirty air filter, a clogged fuel system, or improper carburetor adjustment. Check and clean your air filter as your next step.
By following this guide, you’ve taken control of a fundamental piece of lawn mower maintenance. The ability to remove lawnmower spark plug is a quick fix that solves a majority of starting issues. With a little practice, this whole process will become a routine part of your lawn care season, keeping your equipment reliable for years to come. Remember to always put safety first, disconnect that spark plug wire, and work on a cool engine.