Your lawn mower is an integral—and expensive—piece of equipment that helps keep your yard looking its best all throughout the year.
But because you likely use your lawn mower infrequently (generally once a week at the height of the season), it’s easy to overlook the basic, but necessary, upkeep that can help it continue performing at its peak for a decade or longer. And if you don’t properly maintain it, a poorly running lawn mower might end up causing many more problems than it solves.
The good news is that lawn mower maintenance is a relatively straightforward process. In this guide, we will share lawn mower maintenance tips that will help you ensure this key piece of equipment hums along during the busy spring and summer months, and sleeps comfortably during winter hibernation.
Read Your Owners Manual First
If you’ve been using your lawn mower all season long, it’s likely that you’ve already thumbed through the owner’s manual to familiarize yourself with its basic features and operation. If something went wrong during this time, then you probably referenced it again (maybe several times!) looking for replacement parts or troubleshooting assistance.
Now that the daylight hours have begun waning and the season is coming to a close, it’s a good idea to reread your lawn mower’s owner’s manual for recommendations about oil levels, spark plugs, air filters, blade sharpening/replacement, and much more. Even if you’re familiar with small engine maintenance, it’s still a good idea to check your owner’s manual and make sure that you’re not missing something, or that your specific mower doesn’t require specialized maintenance that your previous mowers didn’t.
However, we understand that your garage is already full, and hanging on to the manuals for each piece of equipment you own could be considered a waste of space. So, if you’ve already thrown out your mower’s manual, be sure to check out websites such as MowersDirect.com, which allows you to search for manuals based on a model. Alternately, you can visit the manufacturer’s website directly, which will usually feature manuals for current and previous models that can be downloaded and printed as you see fit.
With this out of the way, let’s dig into the mower itself.
Maintaining the Lawn Mower’s Fuel System
Similar to your digestive system, your mower’s fuel system provides the energy it requires to give your lawn a perfect, uniform appearance. However, just like your body, your lawn mower’s fuel system isn’t comprised of just one part, but of several, each of which plays a crucial role. In fact, if even just one of these parts isn’t operating efficiently, it can spell doom.
As such, let’s take a closer look at each:
Most modern lawn mowers feature molded plastic gas tanks, although if yours is an older model, it might be made of steel. Plastic tanks are generally considered more durable, as you rarely have to worry about rust forming on the inside of the tank, and dents and dings that can impact storage capacity are largely a thing of the past.
Whether your lawn mower’s gas tank is plastic or steel though, it’s possible for debris to accumulate inside, which can eventually make its way into your engine and cause serious problems.
To prevent this, grab a flashlight, remove your mower’s gas cap, shine it inside your tank, and search around to see if you find any floating debris. If you do, drain your tank and use a turkey baster (not the good one used during the Holidays!) to suck up the little bits of debris and deposit them into the trash.
Speaking of which, all modern gas caps should have a tiny hole in the center that allows air into the tank. If yours doesn’t, this could lead to vapor lock and should be replaced.
But hold on one second, because there are other parts you need to be aware of before draining the tank.
After leaving your tank, gas enters the fuel lines, which are generally made of plastic or polyurethane tubing and work to carry the fuel to the filter (more about this next).
Since they constantly have gas running through them, and because they’re often exposed to the elements and the high heat of your mower’s engine, these fuel lines can become dry and cracked and eventually start leaking.
If this occurs, replacing your fuel line is often as easy as purchasing new tubing from your local home improvement store, grabbing a pair of pliers and a bucket, trimming the lines to the appropriate length, and putting them back in place.
Next, once the gas has been pushed all the way through the fuel line, it will then enter the fuel filter. As the name implies, this key lawn mower part removes particulate matter from your fuel, such as dust, dirt, and other debris, by passing it through a paper filter (much like an air filter, which we’ll talk more about shortly). Otherwise, this harmful debris could enter your carburetor or engine and cause serious damage.
Just like any other type of filter though, your mower’s fuel filter can become clogged with impurities over the course of a season and will need to be cleaned or replaced.
In order to clean your fuel filter, first, clamp all fuel lines to prevent spillage, and place a small catch pan under the area where you’ll be working. Then, remove the filter, spray it with carburetor cleaner, and gently tap loose any remaining debris.
Pro Tip: In many instances, the paper portion of a lawn mower’s fuel filter is enclosed in a hard plastic or metal shell, which means that it won’t be able to be cleaned using this method. If this is the case with your mower, you may need to purchase a new replacement filter, although this often costs less than $10.
Once the gas has passed through your fuel filter and cleaned, it will enter the carburetor, which mixes the gas with air before entering the engine. If you own a high-end lawn mower, it may feature fuel injection, in which case you can skip over this section.
If your carburetor is running too lean, this means that there isn’t enough fuel in the mixture. On the other hand, if your carburetor is running rich, then this means that you’re getting too much fuel and not enough air. In either instance, this can lead to problems starting your lawn mower, maintaining a smooth idle, reducing its power output and fuel economy, and more.
As such, it’s important that you read through your owner’s manual to learn how to properly adjust your carburetor so that your mower can perform at its best.
While there are hundreds (perhaps even thousands) of different carburetor models commonly featured in lawn mowers, most feature two primary parts: adjustment screws and needles.
A diagram showing the main parts of a lawn mower carburetor. Image credit: Jerlober.com.
Among the adjustment screws, you’ll typically have two types: the idle adjust, which alters your engine’s idle speed, and the main adjustment screw, which directly alters the amount of air that’s pulled into your carburetor.
Here’s where things get tricky, because properly adjusting your carburetor’s jetting often requires some trial and error, although the more familiar you are with how your mower performs, the easier the process will be. As such, if your mower is newer or you’re not comfortable adjusting the jetting, you should take it to a certified dealer for maintenance.
In most instances though, if your mower isn’t running properly, you should set your main adjustment screw as lean as possible, and then start the engine. It will likely sputter a bit, at which point you’ll need to rotate the main screw counterclockwise, one quarter turn at a time until it’s running perfectly. If your mower’s exhaust becomes dark and smells excessively like gas, you might be running too rich, which means you should turn the screw ¼ turn clockwise until this ceases.
Then, if your mower isn’t idling properly, you can adjust the idle screw.
Now that we’ve discussed the importance of your lawn mower’s fuel system, things to look out for, as well as a few key maintenance tips, let’s talk spark; your spark plug that is.
Replace the Spark Plug Once Every Season
When it comes down to it, whether it’s a small engine in your lawn mower or a huge engine in your car, they all require three main things to start up on the first kick:
- Fuel (which we’ve already discussed),
- Air (which we’ll discuss next), and
- Ignition, or spark, which is provided by your spark plug.
Pro Tip: Once they’ve been started, engines also require compression in order to remain running and to function properly. However, due to the hundreds of different causes of poor compression, as well as the huge problems that can occur as a result, we won’t go into detail here. Instead, if your lawn mower won’t continue running after starting or is otherwise suffering from poor compression, we’d recommend taking it to your local repair facility.
At its most basic, a spark plug is a “device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air mixture by an electric spark, while containing combustion pressure within the engine.” In other words, your mower’s spark plug is what causes the air and fuel in the engine to ignite, a process known as combustion.
Because of its importance, as well as the fact that the gap in your spark plug can become clogged with deposits over time, most lawn mower manufacturers recommend that the spark plug is replaced once every season. However, in the interim, you should regularly remove your spark plug and use a wire brush or spray-on cleaner to remove these deposits and help it perform optimally.
With this covered, let’s talk about the next piece of the puzzle in helping your lawn mower perform its best: air flow.
Clean the Air Filter
Last, but certainly not least, we’ve come to your lawn mower’s need for fresh, clean air, which it mixes with fuel to run your engine.
Similar to the fuel filter, your mower’s air filter removes dust, debris, and other particulate matter before it can reach your engine. As such, this debris can build up over time and will require cleaning, and in some instances, complete replacement. But how can you tell the difference?
As with spark plugs and fuel filters, most manufacturers recommend that you clean your air filter at least once per season, although this might require more frequent maintenance if you live in an especially dry or dusty climate.
To clean, simply remove the air filter according to the owner’s manual and tap the filter several times, at which point you should see a decent amount of dirt falling out. After you’ve tapped several times, most of the loose dirt should have fallen away, but if it doesn’t, this might mean that the filter has become oversaturated with debris and requires replacement.
Pro tip: There are thousands of different air filter configurations for lawn mowers, although they all basically boil down to two types: paper and cloth/foam.
Paper filters are generally the least expensive option, although they tend to quickly restrict airflow and reduce performance once debris accumulates, and often can’t be thoroughly cleaned. Cloth/foam air filters generally require a bigger upfront investment, although they won’t restrict airflow and can be cleaned and reused across multiple seasons.
Also, keep in mind that after cleaning or replacing your air filter, you may need to readjust your carburetor in order to achieve the optimum air/fuel mixture.
Speaking of replacing things, let’s talk about oil next.
Change Your Oil and Change It Often
Just like your car or any other vehicle using an internal combustion engine, your lawn mower will require fresh, clean oil on a regular basis.
As such, most mower manufacturers recommend that oil is changed every 20 to 50 hours, although this can vary depending on a variety of factors. As such, we’d recommend checking your owner’s manual to learn how often your oil should be replaced, the type of oil you should use, and any other important precautions.
“Great,” you might be thinking to yourself. “These are some awesome tips for gas mowers. But what if I have an electric lawn mower?”
Maintenance Tips for Electric Lawn Mower
Without an internal combustion engine, most of what we’ve talked about up until this point won’t directly apply to an electric lawn mower, since an electric mower’s engine is its battery.
However, despite the fact that electric mowers generally involve less maintenance than their gas-powered counterparts, you should always make sure the battery is in good condition by checking the connections, and by making sure the poles are free of grass, dirt, and other debris.
Other Important Aspects of Lawn Mower Maintenance
Whether you own a gas or electric mower, outside of your engine and fuel system, there are two more important considerations to keep in mind if you’re looking to get the best performance possible out of it.
A Sharp Blade Equals a Sharp-Looking Yard
The first is your blade. After all, regardless of how well your mower’s engine is running, if it’s just ripping your grass instead of making clean cuts, all your hard work could be moot. Not only will your grass require more passes to cut, but it could also lead to unsightly brown patches.
Note: For more tips on achieving the perfect lawn, be sure to read 5 Tips For Achieving the Greenest Grass on the Block this Spring.
In order to ensure this doesn’t happen, sharpening your blade is a task that even a novice can handle, which most manufacturers recommend doing twice every season. This simply involves removing the blade using a socket wrench and then sharpening it with a grinding wheel. If you don’t have a grinding wheel available, you can even use a fine file or sharpening stone.
On the other hand, if your mower’s blade has a lot of big nicks in the cutting surface, or if it’s already been sharpened several times, then you might need a new blade altogether. Lawn mower blades are fairly inexpensive, so you might even consider keeping a spare around just in case.
Keeping Your Mower Clean
As with any other piece of yard equipment, even if your lawn mower is brand new, it will quickly become dirty. And while most of this is just cosmetic (e.g. dirt and dust), grass will have a tendency to accumulate on the undercarriage, which can potentially clog the discharge chute.
The good news is that this can largely be prevented by cleaning your mower’s undercarriage (the area where the blade is located) using a stiff wire brush, and then using your water hose to spray any excess debris away. While there’s no set time that this should occur, for best results, you’ll want to clean the undercarriage after each use.
While these are all great ideas for spring and summer when you’re using your lawn mower the most, what should you do as fall and winter approach?
Winterizing Your Lawn Mower
Once the season comes to an end, the sweltering heat of the summer has passed, and leaves have fallen to the ground, it’s time to put away the lawn mower for a bit. And just like during the active season, there are a few key precautions you can take to make sure your mower is ready to go when spring rolls around.
First, most professionals recommend adding fuel stabilizer to the mower’s system, which can prevent the buildup of moisture, varnishing, and the “gumming” of any remaining gas particles inside. Afterward, run your engine long enough to allow the fuel stabilizer to make its way through the mower’s system.
Then, drain all the gas from your lawn mower, which can be accomplished by siphoning it into a spare gas can. Finally, run your lawn mower until it exhausts its gas supply and turns off. After it cools, put it in your garage and you’ll be ready for next season!
If you own an electric mower, the process is simpler, and only involves removing the battery and storing it in a cool, dry place, along with the mower itself.
A Quick Note About Proper Gas Storage
Because the gas kept in your garage likely won’t see the light of day until the weather starts warming up again, it’s important that you understand the proper methods of storing it.
Make sure that gas is stored only in an approved container, which OSHA defines as “holding 5 gallons of gas or less with a spring-closing lid and spout cover, a means to relieve internal pressure and a flash-arresting screen.” These types of cans will also generally be approved by a nationally recognized testing lab, such as “Factory Mutual Engineering Corp (FM), Underwriters Laboratories, Inc. (UL), or federal agencies such as the Bureau of Mines or U.S. Coast Guard.”
You will certainly find other “approval” methods for gas cans, such as DOT, EPA, CARB, and AQMD, although if you’re looking for the best, search for ones that are FM or UL approved.
As you can see, with just a little bit of effort, you can make sure that your lawn mower stays in tip-top shape all year long, whether it’s being actively used or stored away.
Do you have any valuable tips or tricks that we missed here? If so, be sure to leave a comment below.