What are the riding mower parts that require replacement most often?

In the sections below, we’ll describe the most common maintenance and repair parts for your riding lawn mower or lawn tractor.

Riding Mower and Lawn Tractor Maintenance Parts

Engine Maintenance Parts

Tuning up your riding mower’s engine is essential for smooth operation. You’ll typically need these parts when performing an engine tune-up after every season:

• Air Filter -- The air filter prevents abrasive particles from entering the engine's cylinders, which could cause mechanical wear and oil contamination. Our Replacing an Air Filter video shows how to replace the air filter on common riding mowers.

• Oil Filter -- Engine oil lubricates various moving parts within the engine. Oil also cleans, prevents corrosion, improves sealing, and cools the engine by carrying heat away from moving parts. The oil filter removes contaminants from engine oil so the oil works efficiently. Our How to Change the Oil video shows how to replace the engine oil and filter in common lawn tractors and riding mowers.

• Spark Plug -- A spark plug is the device responsible for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine. This current ignites the compressed fuel/air mixture by means of an electric spark, while containing combustion pressure within the engine. To keep the mower running smoothly, replace the spark plug once a year, or as often as your owner's manual specifies.

• Fuel Filter -- The fuel filter screens out dirt and rust particles from the gasoline before fuel enters the carburetor. The fuel filter paper is usually integrated into a cartridge. Replace the fuel filter as specified in the owner’s manual for your riding mower. Our Replacing a Fuel Filter video shows you how.

Engine parts are often listed on a separate parts list from the tractor frame and mower deck parts. Use the engine model number to look up engine parts if you don’t find engine parts listed with the rest of the tractor’s parts. You may also find the part numbers for the above engine maintenance parts listed on the underside of the tractor’s hood. Be sure that you use the right replacement parts when maintaining your riding mower or lawn tractor.

Mower Deck Maintenance Parts

Keeping your mower deck well-maintained insures that the riding mower cuts the grass cleanly and efficiently. In addition to lubricating moving parts with grease and keeping the deck clean, you’ll also need to periodically replace these parts:

• Mower Blade – The mower blade is affixed to the end of a shaft and has one sharp edge on the top side. As the shaft spins, the sharp edge cuts the grass. Because of the upward angle of the sharp edge, the grass blows upward and out to the discharge chute. Over time, blades get dull. They can also get bent and corrode. Replace the mower blade(s) on your riding mower once per season or when they’re dull or damaged. Follow the steps in our Replacing a Blade video to install new blades on your riding mower.

• Blade Belt -- The blade belt attaches to the engine pulley and spins the cutting blade(s). The blade belt typically wears out and can begin slipping after a season of normal use. Replace the blade belt at the end of each cutting season or when it begins to show signs of excessive wear.

• Mandrel Pulley -- The mandrel consists of the housing, bearings, and blade shaft. The mandrel mounts to the mower housing and has a pulley on top. When the user engages the blades, a belt turns the pulley on the top of the mandrel and spins the mower blade. Bearings in the mandrel pulley often wear out after a season of mowing. Follow the steps in our Replacing a Mandrel Assembly video to install new mandrel pulleys on your mower deck.

Frame and Body Maintenance Parts

You’ll need to periodically replace some frame and body parts to keep your riding mower in top condition.

• Ground Drive Belt – Install a new ground drive belt yearly to keep your riding mower moving properly. The ground drive belt connects the engine crankshaft to the transaxle pulley to drive the rear wheels. Follow the step-by-step instructions in our Replacing a Ground Drive Belt on a Riding Lawn Mower video to install the belt on your mower.

• Riding Mower Head Lights – Head lights will eventually burn out on your riding mower. Find the right head lights for your riding mower by keying your model number into the search bar at the top of this web page. Find the part number for the head light and order the part for your model. Replacing the head light is a simple repair. Lift the hood and remove the socket from the headlight housing and replace the bulb. Reinstall the socket and close the hood.

• Tires – Riding mower tires will eventually wear out over time. Replace the tires when tread wears thin. These videos show how to replace tires on a riding mower:

  • How to replace a riding lawn mower front tire

  • How to replace a riding lawn mower rear tire

Sometimes you can use Tire Sealant to fix small leaks in the tire instead of replacing it.

Common Riding Mower and Lawn Tractor Repair Parts

When your riding mower or lawn tractor breaks, you’ll want to act fast to fix the problem so you can get back to mowing.

Here are the most common replacement parts you may need:

• Engine Flywheel Key -- The flywheel key is a small rectangular piece of metal that keeps the crankshaft and flywheel aligned when you tighten the flywheel nut. To protect expensive engine components from damage, the flywheel key shears off if the mower blade hits an object hard enough to make the flywheel slip out of alignment with the crankshaft. Replace a broken or sheared flywheel key using the step-by-step instructions in this video: How to replace the flywheel key on a riding mower.

• Starter Solenoid -- When you turn the ignition key to the start position, the starter solenoid sends current to the starter. If you don’t hear the internal solenoid contact click when you turn the key, diagnose the starting failure using our Riding Mower Doesn’t Crank or Click troubleshooting video and replace the starter solenoid if it isn’t working. Follow the step-by-step instructions in the How to replace the starter solenoid on a riding lawn mower video to install a new starter solenoid.

• Riding Mower Battery -- The battery provides the electrical current needed to power the starter motor. Replace the battery when it’s weak or dead and won’t recharge.

• Alternator -- The alternator is a set of wire coils under the flywheel of the engine that generates electricity to power the tractor when it's running. The alternator also recharges the battery while the engine runs. You may need to replace the alternator when it doesn’t recharge the battery as the engine runs.

• Seat Switch -- The seat switch is a safety device that shuts off the engine if it doesn't detect someone in the seat when the tractor starts moving. If the seat switch breaks, it won’t sense that you’re in the seat and will stop the engine when you release the brake. Replace a broken seat switch on your lawn tractor or riding mower using the step-by-step instructions in this video: How to replace the seat switch on a riding lawn mower.

• Starter Motor -- The starter motor spins the flywheel to start the engine when you turn the start key. If you hear the starter solenoid click but don’t hear the starter motor run, watch this riding mower troubleshooting video to help you diagnose the problem. If the starter motor doesn't spin when you turn the key, install a new starter motor by following the instructions in this DIY repair video: How to replace the starter motor on a riding lawn mower.

Although these are some of the most common repair parts that you’ll need to fix your riding mower when something goes wrong, there are many other problems that can occur. Follow the DIY repair advice in our Lawn Tractor and Riding Mower Repair Help section to fix other failures.

If you get to a point where you’re not completely confident that you can repair your riding mower yourself, schedule a Sears Technician to diagnose and repair your mower.