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Tune Up Your Lawn Mower for Spring

Old Lawn Mower on green lawn

Though there may still be snow on the ground in some northern areas, baseball season is back and that means lawn mowing season is here as well. No matter if you have a riding mower, a simple push mower, or a fancy new lithium ion battery powered electric, there are periodic maintenance items that need to be done. Mowing is a chore even when it is easy, and nobody needs a poor running mower, or one that gets bogged down when the going gets tough and the grass gets long, to make it even harder.

If you put the mower away properly, and stored it indoors with no gas in it you should have no problems in spring. If you aren't going to run the tank and carburetor dry, you should at least add a shot of fuel stabilizer to a tank no more than half full, and fill up with fresh gas come the spring thaw.

1) Clean up

If you are like most people, you put away your lawn mower last year without even thinking that it was going to be sitting around for three or more months. If you do nothing else, giving it a good cleaning before you start mowing again is a good idea.

Air cooled motors cool better if they are clean so wash and scrub the fins just like you would the wheels of your car. Mowers are fairly durable, but you should identify the fuel vent, and air cleaner, and avoid getting water in them.

Now, jack up your riding mower (and support it properly), or flip your push mower on its side (careful - fuel may leak out if tilted too far), and clean all of the dead dried grass off of the bottom of the deck. If you have an electric mower, cleaning under the deck is particularly important, since the vents to cool the electric motor are probably under there. Once it is clean, spraying the underside with WD-40 or other aerosol lubricant will help keep it clean and prevent rust.

2) Inspection

While cleaning, this is a great time to give your mower the once over and look for wear, breakage, and general loosening of bits and pieces. Start with the handle (on a push mower) and make sure all the bolts and knobs holding it on are tight. Lubricate any control cables and linkages, and check any wiring for breaks of loose connections. Next make sure the controls are tight, and operating properly. Check the motor and the whole unit in general for screws and bolts that may be coming loose.

On riding mowers and self propelled push mowers, check that the belts or chains aren't worn out or loose; often these can't be adjusted and need to be replaced if they get slack. If there are drive chains (some reel mowers and riding mowers) make sure they are clean and lubricated, and all the links move freely.

On push mowers, check each wheel to make sure it rolls freely, and isn't cracked. On riding mowers, and others with pneumatic tires, check the air pressure; be careful though, the proper pressure is less than you think (most are 10-15 psi). If there are grease fittings, use a grease gun to lubricate the wheels bearings.

3) Sharpen the blade

Having a good sharp edge on the blade or blades of your mower is the single most important thing you can do to improve your lawn care routine. Not only does a sharp blade make mowing quick and easy, it results in healthier, greener grass. A sharp blade makes a clean cut which the grass recovers from quicker, letting it grow stronger and thicker. Grass cut with a dull blade will leave damaged ends which turn brown, bringing down the whole look of the lawn.

You can sharpen the blade any number of ways (whet stone, file, grinding wheel) but the easiest is probably the beveled grindstone which attaches to your drill. For less than $20 at any hardware store, you can get one of these sharpening kits and be mowing better in minutes.

Taking the blade (or blades) off shouldn't require too much effort, but it may be helpful to use a piece of wood to jam it in place so it can't rotate as you loosen the nut. When reinstalling be sure to get the retaining nut tight enough. The proper torque is different depending on the diameter of the shaft, but don't worry about overtightening it.

On a mower with two blades, one may rotate in the opposite direction, and the nut may be reverse threaded.

The old fashioned reel mowers are a bit more complicated when it comes to sharpening and adjusting them. They typically require an adjustment of the straight blade at the back, then cranking the reel backwards with an abrasive lapping compound until they work just like scissors through paper.

4) Tune the motor

Gasoline burning lawnmower motors are amazingly durable, considering how many years they typically run for with zero maintenance by their owners. With a little care though, they can last even longer.

Just like a car, your mower needs an oil change occasionally, as well as an air filter, and a new spark plug. If your mower has a pleated paper air cleaner element, remove it and tap it to shake free the loose dust. Replace it if you can't see light when you hold it up in front of your eyes. If your mower has a foam element, wash it in soapy water and apply a small amount of air filter oil (gear oil will also work in a pinch).

If you are lucky, your mower will have a drain plug accessible from under the deck. If the drain plug is in the side, above the deck, lean the mower over and try your best not to make a mess draining it. Refill with the recommended motor oil. Most small engines in mowers only need about 1/2 quart of oil, so it is important that it stay clean and full if you want it to last.

The spark plug on most mowers can go several years without needing replacement, but if you find yourself having to pull the starter more than a few times to start the engine, a new plug will help. It doesn't hurt to remove the old plug and inspect it to see what sort of condition it is in once a year.

Spark Plug Condition Chart
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