How to Winterize Your Lawn Mower [UPDATED FOR 2021]

How to Winterize Your Lawn Mower [UPDATED FOR 2021]

As another lawn mowing season comes to a close, it may be tempting to roll your lawn mower into the far corner of your garage and forget about it until spring.

But winterizing your lawn mower is a critical part of ensuring that it continues to run properly for years to come. Neglecting to prepare your lawn mower for winter storage will have you shopping for a new one in no time.

Below, we’ll explain how to winterize your lawn mower for the cold weather ahead and offer suggestions if you’re new to lawn mower winterization. Proper maintenance now will ensure that your lawn mower is up and running in the springtime.

WARNING: Always read the engine and equipment manual(s) before starting, operating, or servicing your engine or equipment to avoid personal injury or property damage.

CLEAN THE DECK

Underside of mower caked with grass
The underside of a mower caked with grass

You may be wiping down and cleaning off the top surfaces of your lawn mower, but one of the most commonly overlooked tasks of winterizing a lawn mower is cleaning the underside, otherwise known as the deck. Over the course of a mowing season, layers of grass clippings build up on the underside of your lawn mower. Because they hold moisture, these grass clippings can cause rust and will ultimately impact the performance of your mower. Cleaning the deck should be done at least twice a year.

underside of mower removing caked grass
Removed caked grass from underside of a mower

To clean the deck, turn your mower over and scrape off the grass clippings with a putty knife and wire brush, then wipe off any remaining grass residue with a dry towel. Debris and blades of grass should be removed from the mower deck, the lawn mower blade, and other components. For maximum results, use WD-40 to coat the underside of your deck.

REMOVE AND CHANGE THE SPARK PLUGS

bad spark plugs old used black and white

Evaluate and remove the spark plugs. Plugs that are corroded or cracked must be replaced with a new plug. Keep in mind that spark plugs are generally only designed to be used for 100 hours of mowing (and you can trust that they’re much cheaper to replace than the entire mower).

You can identify a bad spark plug by looking at it. Use a socket wrench to unscrew the plug so you can inspect the electrode and insulator, then look closely: the center of the electrode should have a flat top. If it appears rounded, cracked or blackened from carbon or degraded excess fuel, it’s time to replace it.

CHANGE LAWN MOWER OIL AND OIL FILTER

Changing the oil prepares your lawn mower for winter storage and can ensure that your mower will start properly next spring. Be sure to warm the engine before changing the oil, then move your mower onto a drop cloth in a well-ventilated area. Disconnect the battery and remove the spark plug, then check its oil level with a dipstick. At the end of a mowing season, the oil will likely be black.

To drain the oil, use a valve, hose and pan, then check the oil level again to ensure the tank is empty. Add fresh oil to your mower according to the manufacturer’s instructions. Next, use an oil filter wrench to remove and replace the old oil filter.

ADD FUEL STABILIZER TO THE GAS TANK

Although it may seem like a good idea to drain the fuel tank, doing so could harm your engine. It will be harder for your lawn mower to start next spring if you run it dry before storing it for winter. Note: this concept is universal for all of your outdoor equipment and tools, from mowers and blowers to trimmers and chainsaws.

DRAINING THE TANK HARMS YOUR LAWN MOWER’S CARBURETOR

You can easily damage critical parts of your lawn mower by draining the tank, including the carburetor. Because your lawn mower’s carburetor blends air and fuel and circulates these elements into an engine’s cylinders, it’s one of the most important elements of a functioning lawn mower. Each time you drain the gas tank, oxygen enters the lawn mower’s carburetor. Because it’s impossible to drain every last drop of gasoline, oxygen attacks the small fuel droplets left behind, causing it to gum and varnish. When this debris settles in the wrong place (a needle valve tip, for example), the carburetor will need cleaning to work properly again. Anytime there’s oxygen, there’s also water, which causes damage. In fact, moisture is the most common cause of damage to your mower over the winter season.

AVOID THE RISKS OF DRAINING THE TANK WITH GAS STABILIZER

Manufacturers often recommend draining the tank to winterize a mower because leaving old, stagnant fuel in an engine during long periods of storage can be damaging. You may have heeded this advice in the past without incident, but that doesn’t mean you’re in the clear. If you’re draining the tank on an annual basis, there’s a very good chance that you’re shortening the lifespan of your lawnmower.

The best way to properly maintain your lawn equipment and avoid damage is to simply use a quality fuel stabilizer and fresh fuel before storing it away for winter.

DISCONNECT AND REMOVE THE BATTERY

Removing your mower’s battery for the winter is one of the best ways to preserve its power. You can disconnect the battery by starting with the negative lead and then unplugging the positive lead. Be sure to clean any dust or debris off the battery with a dry cloth. Store the battery in a cool, dry area away from any heat sources (like a furnace) or flammable substances (like gasoline).

REPLACE THE AIR FILTER AND FUEL FILTER

riding mower air filter

Your lawn mower’s air filter and fuel filter prevent debris from reaching and damaging the carburetor. Plan to change them at least once per season to keep your lawn mower performing at its best. Doing so before spring will ensure that you don’t forget.

REPLACE OR SHARPEN AND BALANCE THE MOWER BLADES

Sharpening or replacing your mower blades is a good habit to practice while you’re preparing your lawn mower for storage. Because dull blades can actually harm the grass on your lawn, sharpening your blades once a year is highly recommended. You’ll thank yourself in the springtime for completing this lawn mower maintenance task now.

ADDITIONAL MOWER WINTERIZATION TIPS:

  • Check mower deck belts, bearings and idlers: Issues with these mower parts will affect your mower’s ability to make a clean and even cut on your grass.
  • Check transmission belt and idlers: Lawn mower belts wear over time – if they’re neglected, they’ll eventually break.
  • Lube all grease fittings: Lubing grease points throughout the mower plays an important role in routine preventative maintenance.
  • Check tire pressure and level the mower deck: Ensuring that all tires have the same correct operating pressure and leveling the mower deck will help your lawn mower to maintain an even and level cut.
  • Set engine RPMs: Proper cutting depends on the mower blades’ ability to turn quickly at higher throttling. Small engines often need a higher RPM to burn fuel efficiently, which will also reduce carbon buildup and result in a cleaner engine.

HOW TO STORE YOUR LAWN MOWER FOR THE WINTER:

Avoid storing your mower dry and without gas. The air gap promotes condensation, which worsens with ethanol fuel. If possible, use the Star Tron (by Star Brite) stabilizer. Always store your lawn mower in a cool, dry location away from flammable substances like gasoline or heat sources like furnaces or water heaters.

Preventative maintenance for your lawn mower will pay off when you go to start it next year and extend the life of your mower

Having trouble or need a lawn mower tune-up? We’ve been repairing lawn mowers for over 20 years, servicing nearly every brand of lawn equipment on the market. Call us, stop by or ask us about our parts store or pick-up and drop-off services.

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