Riding Mower Maintenance and Repair Guide

When I was 12, I accidentally drove my dad’s riding lawn mower over a garden hose. There was a sickening change in the engine noise, and black smoke billowed from under the mower deck. I immediately shut down the machine as my dad came running.

Needless to say, he wasn’t happy. We jacked up the mower and discovered not only the ruined hose tangled around the blades, but a broken belt, too.

Luckily for me, my dad turned this into a life lesson. Within 15 minutes we freed the broken hose from the blades, and began installing a new belt Dad kept in reserve. Just like that, the mower was fixed. I finished mowing the lawn and learned something valuable: With a little knowledge and a few spare parts, I could repair the mower.

From that day forward I became interested in DIY repairs of all sorts, thrilled I no longer had to feel helpless when things broke. And neither do you. Keep reading for my best insights on riding lawn mower repair and maintenance.

How To Tune Up a Riding Lawn Mower

Follow these steps for a basic tuneup:

Clean or change air filter

Air filters allow air to flow into combustion chamber, ensuring the correct gas/air mixture while keeping out dust and debris. Over time, air filters become clogged, causing your mower to run rich and burn too much gas. If ignored, your mower won’t run at all.

So it’s important to inspect your riding mower air filter once or twice a year. If it seems clogged, replace it. Air filters are cheap and easy to find. You can also get more life from your old filter by removing and blowing it out with an air compressor and spray nozzle attachment.

Change oil or replace batteries

Like all internal combustion machines, your gas-powered riding mower needs oil to run properly. Regular oil changes are vital for keeping the engine cool and lubricated. You should change the oil after every 50 hours of use, or once every mowing season.

For electric riding mowers, battery life can degrade over time. If your electric mower features standard 12-volt lead-acid car batteries, leave it charging at all times when not in use. Use a volt-meter to check your state of charge before each mowing. If any batteries show less than 12 volts, replace them.

Be sure to buy batteries that match the ones your mower came with. With lithium-ion batteries, you may eventually notice you get less run time out of a charge. When this gets bad enough to affect your productivity, buy a new battery. Here’s how to tune up your lawn mower to keep it running smoothly.

Winterize your mower

Don’t put your gas-powered mower away for winter without running the engine dry to remove all the gas, or adding some fuel stabilizer to the tank.

For electric mowers powered by lead-acid car batteries, hook them up to a charger for the winter. For lithium-powered electric mowers, remove the batteries and store them indoors.

How To Maintain a Riding Lawn Mower

Proper maintenance steps include:

Keep belts in good shape

Raise your mower deck at the beginning of the season and every month or so afterward to inspect the various belts. Are any cracked, frayed or sagging? It may be time for a new belt. Check your owner’s manual for the specific size and type of belts your mower needs, then stock up on replacements, installing them as needed.

Check battery and terminals

For gas-powered mowers, chances are your battery terminals will eventually accumulate dirt and corrosion buildup. This could eventually prevent your machine from starting. Avoid this by inspecting the terminals before each mow and cleaning them with a wire brush if needed.

It’s also wise to check the battery charge with a volt meter several times each season. It it’s lower than 12 volts, your battery needs a good overnight charge or replacement.

Clean the mower deck

This simple job is easy to forget, but neglecting it for too long will catch up with you. Caked-on grass clippings can slow down your blades and lead to poor quality cuts.

If you notice your lawn looking more ragged than it used to after a mow, raise and inspect the mower deck with the machine turned off. Clean all clippings off the blades and the underside of the mower deck. I find a pry bar and pressure washer make a great grass-removing duo.

Store under cover

Don’t keep your mower outside all year and expect it to work well. Rain, snow and sun will lead to corrosion and other damage. Keep your mower dry in a shed or fabric storage shelter.

Common Riding Lawn Mower Problems

Like all machines, riding lawn mowers have lots of intricate parts, and lots of things that can go wrong. I’ve been using and maintaining riding mowers for more than 20 years. Here are the most common riding mower issues I’ve run up against.

Drive belt failure

All riding lawn mowers rely on a rubber or polyester cord belt that turns power from the engine into motion in the wheels. Not surprisingly, these belts occasionally wear out and break.

You’ll know when this happens because your mower suddenly won’t move, or moves with a noticeable decline in power. That’s a sign of a stretched belt.

Stretched and broken drive belts need to be replaced with a new belt of equal length and thickness. Look up the dimensions of your old belt in your owner’s manual or online.

When you’re ready to replace the belt, raise the mower deck to the maximum height and back the machine onto ramps if you have them. Remove the old belt and pop the new one into place on the pulleys.

Note: If you own a zero-turn mower, your machine probably has two smaller drive belts instead of one big one.

Engine won’t start

Most people who ask my advice have the same problem — an engine that turns over but won’t start. Nine times out of 10, their mower has sat unused for months with gas in the tank. This leads to stale gas and possibly a gunked-up carburetor.

The solution: Siphon all the stale gas out of the tank and add fresh gas. After that, the mower will probably start and run fine. Moving forward, drain all gas from the tank or add fuel stabilizer before putting your mower into long-term storage. If it still doesn’t work, then it’s time to replace your mower.

Low-quality grass cutting

Is your riding mower cutting less crisply than it used to? Bad blades could be why. Steel mower blades can easily get dull or corroded to the point where they won’t do their job well anymore. Luckily, this is an easy fix.

Shut off your mower, then raise the deck and inspect the blades. If they seem dull, bent or corroded, buy a new set that matches, based on the description in the owner’s manual. Expect to pay around $20 per blade. To install, raise the mower deck, then use a socket wrench to remove the old blades and add the new. It’s wise to buy an extra set so you have spares on hand for next time.

If your old blades are only dull and otherwise undamaged, you can sharpen them. You’ll need a grinder, along with eye and hearing protection.

Do your best to sharpen the blades evenly so they remain balanced. Test the balance by hanging each blade by its central hole on a nail driven into a vertical surface. If it tips one way or the other, it needs more sharpening on one side or the other until it hangs level.