How To Tune Up A Lawn Mower

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Tuning up your gas-powered lawn mower is the best way to preserve your investment. There are quick and simple tasks you can take that can keep your mower running for years to come. Watch as Ace's Home Expert, Lou Manfredini, gives you a checklist of what to do to your lawn mower from changing the oil and the air filter to replacing the spark plug and blade.


Make sure to get all of the supplies you may need before starting your repairs. Some lawn mower brands even offer convenient lawn mower tune up kits that have a variety of items such as the air filter, motor oil and spark plug, all in one pack.

Replacing Spark Plugs

The spark plug wire can usually be found at the front of the engine on your push mower. Grab onto the cap and firmly pull it off of the spark plug. You can purchase a spark plug wrench that coordinates with the size of the spark plug on your mower.
Spark plugs loosen like a normal nut would, righty tightly, lefty loosely. Loosen the plug all the way out. It may take a little effort or pressure at first, but once you have it started you can loosen the rest by hand. Look on the side of the spark plug for the number that corresponds with your mower.

The reason you want to replace a spark plug is because it get a lot of carbon build up that can make it less effective. Depending on how frequently you cut the lawn, you will want to do this every other year.

When purchasing a new spark plug, make sure it has the same number that your original one has to ensure it is the right fit. New spark plugs are supposed to be pre gapped. If you notice that the piece of metal at the bottom of the plug is smashed and touching the rest of it, that plug is no good, and the metal needs to be pulled away, or gapped.

Put the new spark plug back in the hole and tighten it by hand, finishing by tightening with the spark plug wrench, to make it snug with one little turn. Once you put the plug on, push the cap back on.

Replacing the Air Filter

The air filter is next to the carburetor, adjacent to the gas tank of the unit. The owners manual can help you find the particular location if you are having trouble.

Loosen the screws to expose the air cleaner. The lawn mower's air filter allows the engine to run more smoothly, breathe easier and get more out of a tank of gas. If there is a lot of dirt and debris on the air filter, that means your engine is working overtime, taking more effort to start and using more fuel and hinders the emissions.

Purchase the correct air filter that matches what your mower needs. Brush away any debris on the inside of the filter cavity before you install a new one. Place the new one in where you removed the last air filter. Put the cover back on the air filter and tighten the screws. Some air filters are not screwed on and simply clip on and off, it just depends on your brand and model of push mower.

Change the Oil

Before putting new oil in, you will have to remove the old oil. Some lawn mower models have oil drain plugs, allowing you to unplug it and release the oil without having to tip the mower over. In this case, there is no drain, so we will tip the lawn mower over to pour out the old oil.

Make sure there is no fuel in the tank and remove the dip stick. Tip the mower to the side and pour out any oil from the engine. If you see metal shavings coming out of crank case, you might have a problem with the engine, but if it is dark and black, it is just old and you're doing fine.

Once all the oil is removed, tip the mower back to its upright position. Add the new lawn mower oil, Add about half of an 180z bottle, put the dip stick back into the chamber and see how much oil you still need to put in. Do not overfill the engine, but if you do, it is not a big deal.

Replace Blades

Tip the mower over to expose the blades underneath. There should be a nut attaching the blade onto the bottom of the mower, Simply loosen it using a wrench and remove the blade. Remember that even though you are replacing the blades, they still may be sharp, and to be careful not to cut yourself.

Once the blade is removed, use a putty knife or other scraping tool to get rid of any debris and old clippings that haven't been cleaned out. This will help the mower operate more efficiently, especially if it is a mulching lawn mower.

Attach the new lawn mower blade by orienting it correctly, adding the mounting plate and retightening the nut that we screwed out earlier. Use a wrench to make sure it is nice and snug around the blade.  
For more helpful tips and advice, visit a Neighborhood Ace or visit us online at Ace Hardware's Tips & Advice
Originally Published: 9/2/2021
Updated: 6/3/2022
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