How to Tune Up a Lawn Mower Safely in Under Two Hours (6-Step Guide)

A spark plug ignites the fuel-and-air mixture inside your engine to start the device. Some newer lawn mowers have push-to-start features, so to be on the safe side (and avoid accidentally starting your mower while you’re working on it), disconnect the spark plug to avoid any lawn mower mishaps.

To disconnect it, unscrew the plastic wire and cover it over your plug. For now, this is all you need to do with your spark plug. You’ll replace it at the very end.

With a rag or paper towels and some grease-cutting soap mixed into a small bucket of water (a few drops of soap will do), clean the exterior of your mower, including the base, the mower deck, and the handles.

Avoid tilting it on its side, for now. You can scrub away grass and wipe down the bottom a few steps from now.

A clean air filter makes your lawn mower’s engine run smoother and even preserves gasoline to help you save money. You can purchase lawn mower filters for $5 to $12 at home improvement stores. Your manual will tell you which size or brand you need to buy for it to fit correctly.

Pop the plastic cover off to your air filter or use a screwdriver, and remove the current filter. (The filter is usually next to the carburetor on your mower.)

If it’s still white or looks pretty new, you may be able to simply pull off any small pieces of debris and keep using it. If it’s dirty, you’ll need to install a new one.

Before draining lawn mower engine oil, remove any gasoline from your device. This way, when you tilt the device, there’s no chance that gas will leak out.

Most units have a screw cap on top that holds your motor oil. You’ll need to simply remove this screw cap by hand, then tilt your lawn mower on its side to drain all the excess oil into a pan or bucket. Give it at least five minutes so it can drain properly.

If you notice pieces of metal in your engine oil, this could signal a severe problem with the engine that would warrant you fixing the engine or even replacing the device.

When adding new oil, add half of the 18 oz canister ($5 to $10 at home improvement stores), then use your dipstick to measure how much more you need. Most devices will use the whole bottle, but you may only need three-quarters or slightly less than a full bottle.

While your engine is tilted and draining oil, check the blade for knicks, dents, or damage to the blade underneath. If your lawn mower is a few years old and has never been serviced, it’ll likely need a new mower blade. If it’s totally destroyed, you may need to go through the checklist to decide whether to repair or replace your lawn mower.

Blades cost $20 to $50 online or at home improvement stores. Once again, your owner’s manual will tell you which size your unit needs.

A single bolt holds down most blades, so you’ll likely need a 5/8-inch wrench to pry it loose. Securely tighten the new blade before tilting the lawn mower back to a stand.

Finally, use either a socket wrench or spark plug wrench tool (the latter costs around $10). A firm counter-clockwise turn should loosen it, then you can unscrew it and remove.

On the base of your spark plug, you’ll find a code, which you’ll need to match the correct replacement spark plug for your mower. Install the new spark plug, giving it a firm turn to secure it in place.

You should replace spark plugs biannually.