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Tune Up a Lawn Mower

Tune your lawn mower in 3 easy steps. It'll run better, last longer and burn fuel more efficiently and cleanly.

By the DIY experts of The Family Handyman Magazine

Change the oil and air filter

It's just plain smart to tune up your lawn mower every spring. According to manufacturer Briggs & Stratton, a tune-up can increase fuel economy by a third, extend the life of the engine, reduce repair costs and decrease emissions by up to 50 percent.

The three main components involved in a mower tune-up are the air filter, spark plug and oil, all of which must be changed. The needed parts and supplies can be found at home centers and hardware stores.

Start by changing the oil. Run the engine for a few minutes to warm up the oil so it'll drain better. Stop the engine, remove the drain plug and empty the old oil (tilt the mower back to get it all out, if necessary). Replace the drain plug and fill the mower with oil until it's visible through the oil fill hole, or check the level on the dipstick, if so equipped.

A clean air filter helps maintain the proper fuel/air ratio, allowing the mower to burn less gas. Swap out the old air filter (Photo 1).

Replace the spark plug

Next, remove and replace the spark plug (Photo 2). If the plug's rusted tight, spray it with a penetrating lubricant like Liquid Wrench or JB80. Let it soak in for 10 minutes before trying to loosen the plug again.

The spark plug will be factory gapped, but make sure there is a gap between the electrode and overhanging arm. If you drop the plug and the overhanging arm bends tight to the electrode, the mower won't start.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • Socket/ratchet set
    • 4-in-1 screwdriver

You'll also need a spark plug socket.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • Air cleaner
    • Engine oil
    • Spark plug

Comments from DIY Community Members

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1 - 6 of 6 comments
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March 18, 12:40 AM [GMT -5]

on self propelled mowers, the self propel hardware usually blocks or covers up the oil drain plug on the underside of the deck/engine. easier to just drain the oil out through the oil dipstick tube by tilting the mower on it's side. will give the same result as far as changing the oil. also it is best to use 30 weight oil. 10w30 oil sometimes especially in the southern states will cause engine to run too hot and will make it hard to start when hot. 30 weight does a lot better protection agains heat in the southern states. I am sure 10w30 will do fine in the cooler climates . -thanks.

July 21, 7:05 PM [GMT -5]

1. Place a dab of dielectric grease on the spark plug tip (tip only) before replacing the wire. (dielectric is right. in grease it means it aligns with current, not insulates)
2. Use auto wheel cleaner over the entire mower, only when cool, and hose it off strongly; you'd be amazed at the nooks and crannies that get filled with dirt/gunk. (Stuff that will keep it from running next spring). Putting a plastic bag over the air intake won't hurt.
3. Since cleaning a carb correctly is beyond this, if the machine is more than 2 seasons old, run some carb cleaner in the next tank of gas. Get the proportions right.
4. Buy a little blade sharpener (drill or manual) at the big box stores and touch up your blades. They'll last much longer. (disconnect the plug. AND BLOCK THE BLADE WITH A PIECE OF WOOD; you do that by jamming the blade and the wood piece where they can't move.)
5. Lubricate your cables. Seriously. They stretch less and will delay a tune up. Pour some very lightweight oil (NOT WD40) into the top ends; a piece of duct tape will make a good funnel, just keep the sticky side out.

July 07, 5:08 PM [GMT -5]

when tuning up a lawn mower, never spray wd40 unless you plan on hosing off mower. I did it once and nearly caught a tractor on fire.

June 22, 6:00 PM [GMT -5]

Spark plug wire should be disconnected before working under mower

June 22, 5:58 PM [GMT -5]

Spark plug wire should be disconnected before working under mower

June 22, 5:58 PM [GMT -5]

Spark plug wire should be disconnected before working under mower

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