Lawn Mower Maintenance

Learn these basic mower mechanics in order to maintain and prolong the life of the lawn mower you have. It's easier than you think!

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Learn these basic mower mechanics in order to maintain and prolong the life of the lawn mower you have. It’s easier than you think!

If you’re not mechanically inclined by nature, the notion of taking care of your own lawn mower might seem downright intimidating. While there are a few things to keep track of, all of them are pretty easy, and mastering them is quite enjoyable.

Use the checklist that follows to develop a habit of preventative mower maintenance. If you haven’t had much experience maintaining your own machines, err on the side of caution and check things frequently — you’ll naturally scale it back as you figure out what’s right for you. The extra time spent holding a wrench in the beginning will serve you well later, when you really need to fix something — and besides, it’s fun!

Mower mechanics

Gas mowers are like little, simple automobiles, and the things you learn here could even be the first steps in learning how to take care of your own car. Some of the basics are similar.

Before doing anything else, remove the spark plug caps and unscrew the plug(s). This will prevent the mower from having any chance of starting accidentally while you’re tinkering with a belt or blade. Be sure to cover the open sparkplug hole(s) with lint-free cloth rags to prevent cylinder-damaging debris from dropping in. If plugs are worn, just replace ’em — they’re pretty cheap. Use an anti-seize compound on the threads so that you can replace them later without pulling a muscle or ruining the threads in the cylinder head. You might even keep a couple of spares on hand. Buy plugs that are pre-gapped for your engine — your owner’s manual will indicate the appropriate gap.

If you didn’t drain your gas last fall before putting the mower away for the winter, do that now — stale gas makes a mower hard to start and difficult to keep running.

If the mower has a separate oil reservoir (and you didn’t change the oil in the fall), drain it and replace it with fresh. Check the owner’s manual, but most four-stroke engines take 30-weight oil. Check the oil and gas before running the mower each time. Note that old two-stroke engines will require mixing the oil and gas before putting it in the gas tank because they don’t have a separate oil reservoir.

Most mowers are air-cooled, so take the time to clean the gunk out from between the heat sink fins — you can use a dowel, stick, screwdriver, compressed air, etc. — and it will increase the life of your engine; too much heat causes extra wear and tear.

Take out the air filter and give it a going over every 25 hours or so of mowing — if it’s ragged or really dirty, replace it, otherwise clean it by tapping it on something to get the worst of the dust out and then stick it back in place. Make sure the housing and cover are clean before closing everything up. Often, wiping them with a damp (not wet) rag will handle this.

If you have a self-propelled model, it might be a good idea to take a moment to look at the belt and replace it if it’s cracked or worn.

Scrubbing the deck

Grass cakes onto the bottom of the deck while you work — more than usual if the grass is wet. Taking time after mowing to scrape or spray the grass off of the mower will help keep the deck from rusting. Some newer mowers even have a valve that connects to a garden hose on top of the deck, allowing you to spray water into the deck while the blades run, giving your mower a “spin rinse.” Applying oil or a rust preventative after cleaning will lengthen the mower’s life even more.

Plug and play

Electric mowers require much less maintenance than those powered by gas engines — you just have to remember to plug them in.

Try not to completely drain the battery in a battery-powered electric mower. While many electric mower batteries are deep-cycle — meaning they are better able to handle heavy use — batteries store electricity in a fairly fragile chemical reaction, and if you fully discharge the battery and leave it dead for long periods of time, this can seriously reduce the lifespan of your battery.

If you think you’ll need to mow for a longer period of time than a single charge can handle, consider keeping a spare charged battery on hand. It can save you money in the long run — while the battery may cost more at the outset, it’ll grant you greater flexibility and save the replacement cost of your battery each time it is quickly worn out by repeated deep discharges.

Maintaining your edge

Nothing turns a brisk walk in the fresh air into a miserable chore quite like dull mower blades. Fresh, sharp blades, on the other hand, let your mower sail effortlessly through even tough, tall grasses.

Sharpening your own blades can be pretty easy. The traditional method uses a hand file, but you can do it with an angle grinder and a vise, a bench grinder, or some places even sell a handy sharpening gadget that attaches to a hand drill.

After disconnecting the spark plug wire and unplugging or removing the battery, lift the mower or turn it on its side and remove the bolts and plate that hold the blade. This is a great time to clean your mower deck thoroughly, if need be.

Pull the blade off and hold it steady by clamping it to a workbench or in a vise, and then regrind the edge.

If using a bench grinder or an angle grinder, you might cool the blade in water every so often. If you do too much too quickly without quenching, the grinder can heat the metal too much and cause damage to the blade’s ability to stay sharp.

As you’re grinding, check the balance of the blade by hanging it on a screwdriver (inserted through the mounting hole) and ensuring that it remains level.

It’s important to keep the blade balanced, because it will put less wear on the mower’s spindle and/or engine’s crankshaft and cut more evenly. If the blade is unbalanced, it can cause the mower to vibrate excessively, which will cause wear on the blade bolt(s) and drivetrain.

Once the blade is sharp and evenly balanced, replace it, along with the plate and bolts. A torque wrench is often recommended for getting these bolts just right, and the owner’s manual will indicate just how tight they ought to be.

Some mowers don’t have serviceable blades — these just need to be replaced when dull.

Reel Mower Sharpening

Reel mowers need to be oiled occasionally, and if they begin to lose their clean cut, check your manual and consider either adjusting the bed knife or sharpening it. It’s usually best to leave the reel’s edge to a professional.

Depending on your model, a reel mower might go as long as 10 years without a need for sharpening the blades. Kept clean, well-oiled, and sharp, reel mowers last forever. Because they’re human-powered, they even help maintain their operator, so to speak.