How to Do a Lawn Mower Tuneup Yourself

How to Change Oil

1. Purchase Motor Oil

   Make sure you purchase the correct type of replacement oil. Ask the dealer where you bought the mower, or check the owner's manual when in doubt. If you no longer have the manual, you can probably find the documentation for your mower online.

2. Disconnect Spark Plug

   Disconnect the spark plug wire to eliminate any chance of the mower getting accidentally started. To do this, slide the collar on the spark plug wire off the tip.

3. Drain the Old Oil

   Clean off any dirt around the upper part of the oil tank—the spot where you fill the machine with oil. An old toothbrush comes in handy for this task. Unscrew and remove the dipstick if your oil tank has one.

   On the underside of the mower, locate the oil plug. This is usually located on the bottom side of the mower deck, and it may be covered with grass residue if you don't clean the bottom of your mower routinely.

   Prop up your mower right-side-up on blocks at a slight tilt toward the drain plug. Place an oil pan or other shallow container below the plug, then unscrew the plug counterclockwise and allow all the oil in the crankcase to drain out. You will likely notice how dirty and cloudy this oil is—unlike the translucent amber color of new oil.

4. Fill With New Oil

   Clean off the drain plug with a rag, then screw it back into the drain, opening clockwise. Tighten it securely, but not so tight that you will have trouble getting it off in the future. NOTE: If your machine has an oil filter, also replace this while you are replacing the oil.

   Lift the mower off the blocks, set it on a level surface, then fill the crankcase with new oil to the correct level. Replace the cap and dipstick. Refill the gas tank, then reconnect the spark plug wire. Start the mower and make sure there are no oil leaks. The whole process shouldn't take longer than 10 minutes.

How to Change the Spark Plug

1. Remove the Old Spark Plug

   Disconnect the spark plug wire. This wire is usually quite evident, with a collar that slips over the exposed tip of the spark plug. Disconnection is simply sliding the collar off the end of the spark plug.

   Clean the housing around the spark plug with an old toothbrush and rags. When you remove the plug, the area around the spark plug must be clean so debris can't get inside the engine cylinder.

   Remove the old spark plug with a socket wrench and deep socket (special deep sockets are designed for removing spark plugs).

2. Prepare the New Spark Plug

   Consult the owner's manual for information on the proper gap for the spark plug, then adjust the gap between the side electrode and the tip electrode to the appropriate distance. The easiest way to do this is with a gapper tool. This tool has several styles, but they all have some means of quickly measuring the gap between the electrodes on a spark plug. The side electrode on the spark plug can easily bend up or down to adjust the gap.

3. Install the New Spark Plug

   Screw the new spark plug back into the cylinder on the mower using the socket wrench. There is no need to overtighten; the plug needs to be snug. Reattach the spark plug wire onto the top of the spark plug, then start the mower to check its operation. From start to finish, plan on five to 10 minutes to complete the task.

How to Change (or Clean) the Air Filter

Before changing or cleaning the air filter, determine whether your machine has a paper or foam air filter. Paper air filters are replaced while the foam ones are cleaned. If the foam one is damaged or excessively dirty, optionally, you can get a replacement foam filter.

How to Replace a Paper Filter

1. Remove the Air Filter

   Disconnect the spark plug wire to eliminate any chance of accidental starting. Unscrew the air filter cover. The cover is usually held in place by a long screw that runs through the filter and is threaded into the bottom of the air filter housing, or it can be secured with a wing nut threaded onto a bolt running through the air filter housing. Removing the screw or nut frees the cover of the air filter, allowing it to be removed.

2. Install a New Filter

   Remove the old air filter and insert a matching new filter so the pleats face outward. It doesn't take longer than five minutes to change the air filter. Reposition the air filter cover, and secure it with the screw or wing nut. Reconnect the spark plug, then start the mower to test its operation.

How to Clean a Foam Air Filter

1. Remove the Filter

   Disconnect the spark plug wire to eliminate any chance of accidental starting. Unscrew the air filter cover and remove it. The cover is usually held in place by a long screw or with a wing nut threaded onto a bolt running through the air filter housing. Lift out the foam filter.

2. Wash the Filter

   Wash the foam filter with hot water and a grease-cutting liquid soap. Rinse the filter thoroughly, then press it with paper towels to remove as much water as possible. (Alternately, some users like to rinse the foam in kerosene, but if you do this, the foam must fully dry before reinserting it.)

3. Reinstall the Filter

   Soak the foam filter in clean engine oil. Squeeze out the excess oil using a clean rag. If excess oil remains, it may cause the mower exhaust to emit unpleasant black smoke.

   Check the rubber gasket that seals the air filter to the carburetor. It must be replaced if the gasket has dried out or shows damage.

   Put the filter back in place in the housing, then reattach the cover plate. Reconnect the spark plug wire and start the mower to test its operation. The cleaning process takes a little longer than simply changing the filter. Plan for about 10 minutes to clean a foam filter. A foam filter may need about two hours to dry thoroughly in a well-ventilated area if it is washed with water.

When to Hire a Professional for a Lawn Mower Tuneup

Servicing ride-on lawn mowers are best left to the professionals since their motors and housings are a little more complicated. Reel, push, and walk-behind mowers are more straightforward. If you are not confident changing any of these parts or doing this service on your own, hire a local lawn mower repair service to do it for you.

Professionals can also identify issues, odd sounds you hear from your mower, or performance issues you might be experiencing. Most of these maintenance tasks are pretty straightforward to do on your own, but for peace of mind, most can guarantee their work and do it in half the time.

According to Angi, a lawn mower tuneup can cost between $10 to $100.