Spring and Fall Lawn Mower Maintenance Checklist

I hate mowing my lawn. I have allergies that seem to be made worse by freshly cut grass, and it was one of the big chores I endured as a youth. But my time spent behind the blade – and the time spent trying to get my dad’s old mower running again – gave me an early appreciation for what it takes to keep the machine running well. I even made some pocket money working on the neighbor’s mowers and other small engines, and my first job while in college found me as one of the top lawn equipment salespeople at a major retailer. I’ve been around engines, big and small, for my entire life. So, let’s take a look at what it takes to make them last as long as possible.

All walk-behind, gasoline-powered lawnmowers need maintenance twice a year, and the procedures that make sense are different in fall and spring. Begin by reading your owner’s manual for tips on required mower maintenance, then follow the list here to get your lawn mower ready for spring.

Spring Lawn Mower Maintenance Checklist

Tune up your lawn mower

Before you roll it out of the garage or shed in the spring, take some time to tune up your lawn mower to keep it running smoothly. An hour spent at the beginning of the year will help ensure your mower starts quickly every time you go to do your weekly chores throughout the season. All of the steps below are part of the tune-up process. For safety, before attempting any of these tasks, remove the spark plug wire from the engine’s spark plug so the engine won’t be able to start.

Sharpen or replace the blade

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It’s always a good habit to sharpen the cutting blade at least once a year because a sharp blade cuts the grass more cleanly. A dull blade, on the other hand, rips at the grass and could make the lawn more susceptible to disease and deterioration. The blade gets dull through regular use, but if you have a number of trees on your property, hitting exposed roots can quickly dull or even bend the blade. If your blade is bent or severely chipped, it might be time to replace it. Either way, you can remove the central bolt holding the blade onto the motor with a socket and ratchet, using a block of wood to keep the blade from turning.

Replace any drive belts

Many self-propelled lawnmowers use a belt to transfer power from the engine’s output shaft to the drive wheels. These belts, much like the fan belt on your car, can dry out and stretch over time, rendering them less effective. Replacing the belt is a quick, easy, and inexpensive way to restore the drive back to your mower.

Check, clean, or replace the spark plug

The lawn mower spark plug ignites the fuel and air mixture inside the engine of your mower so it will run. But spark plugs get dirty or start to fail electrically, so it’s important to check it before you start cutting the grass in the spring.

To check it, disconnect the spark plug cable by gently pulling it, and remove the plug with a spark plug socket and a ratchet. Inspect the tip for soot, oily deposits or baked-on carbon that can cause the plug to fail. If it’s dirty, you can clean it off or replace it.

A spark plug in good condition from an engine that’s running well will be light gray or tan in color.

To reconnect the wire once you’ve cleaned the spark plug, simply push the connector on the end of the wire all the way over the end of the spark plug as far as you can. Do not reconnect the spark plug wire until the mower blade is secured.

Change the lawn mower oil

The more you use your mower, the more contaminants and moisture will get into the old oil, leading to corrosion inside your engine. Before changing the lawn mower oil, remove the spark plug cable. This will prevent the mower from starting when you tip it up to drain the oil, an important safety measure.

Next, remove the dipstick and tip the mower over until the oil starts draining out. Take note of how you’re tipping the mower over – be sure to keep the air filter and carburetor up so oil and fuel don’t leak into the carburetor. Make sure to drain the oil into a pan so that you can dispose of it properly and safely. Most counties or cities offer a place where you can recycle old oil, which helps prevent it from contaminating the groundwater.

After the old oil is out, you can add new oil. Make sure it’s the right type of oil for your lawn mower; just check the manual for the manufacturer’s recommendation. Add the new oil with a funnel to prevent a huge mess. Let it settle for a few minutes, and then check the dipstick to ensure that the oil is at the proper level.

Clean or replace the air filter

Any engine requires a supply of fresh, clean air to run properly. Over time, the air filter can get clogged with dirt, debris, and grass, which will keep the engine from running its’ best. The air filter is typically mounted on the side of the engine and attached to the carburetor. Usually, one or two screws will release the air filter. If it’s caked with dirt, replace it – small engine air filters are inexpensive and typically easy to find.

Fill the tank with fuel

Make sure the fuel is fresh. If you have old fuel that sat in a can over winter, add it to your vehicle gas tank next time you get a fill-up.

If your mower has a four-stroke engine, it’s made to burn unmixed gas just as it comes from the pump. If your mower has a two-stroke engine, it requires special oil to be mixed with the gasoline before it goes into the tank. The owner’s manual will explain how much oil to add to a given volume of gas.

Oil the axles and controls

A few drops of machine oil on each wheel axle and all control pivot points will help them work much more smoothly. This is a little thing, but it makes a big difference.

Roll the mower outside and fire it up

If your lawn mower was running well in the fall, it should start up after a few pulls in the spring. If your mower doesn’t start, remove the air filter and pour a teaspoon of gasoline down the intake port of the carburetor. Replace the filter, switch the ignition ON, then pull the cord. You should be all set for another great-looking lawn this season.

Fall Lawn Mower Maintenance Checklist

Either run the engine dry or use a fuel stabilizer

You might not realize this, but gasoline does go bad over time. You probably don’t notice this in a car because you’re driving it frequently enough that the fuel cycles through the system quickly, and today’s modern fuel injection systems can compensate for varying fuel qualities. A small engine is a simpler device, however, and since most of us don’t mow our lawns over the winter, the engines can sit for months at a time. The fuel can degrade, leading to harmful deposits and varnishes that will develop within the engine and the carburetor.

There are two schools of thought regarding the storage of small engines. Some people like to use a fuel stabilizer product in their small engine gasoline—a chemical that can help to slow the degradation of fuels. Others, on the other hand, prefer to drain the fuel tank and then run the engine until it’s completely out of fuel. This ensures that fresh fuel is put in the engine come springtime and that the engine stays clean.

Pull the spark plug wire off of the spark plug

This ensures that the mower can’t start accidentally while you’re working on it. If the spark plug is over three years old, replace it with a new one of the same type, so you’re ready for next spring.

Clean the underside of the mower deck

LIUDMILA CHERNETSKA/GETTY IMAGES

All lawnmowers develop layers of caked grass under the mower deck, which can cause poor cutting performance. Set the mower on some sawhorses or tip it up on the ground, and use a small pry bar or stout scraper to remove all caked-on grass.

The underside of the deck does not have to be super-clean, just remove material down to the metal. If the grass clumps are too hard and dry to scrape off, soak the underside of the mower with a garden hose, let the grass soften for an hour, then scrape it clean.

Consider using an engine fogging lubricant

Spraying special oil into the air intake of a running engine before long-term storage is called fogging. It’s the best way to prevent internal engine corrosion of the piston, cylinder and valves of your mower during the off-season. Fogging oil is especially important in regions with cool, damp winters that trigger condensation inside the engine. Winterizing your mower will keep it in good condition for next year.

Source:

• University of Minnesota: Dull Mower Blade; March 2023