Riding Mowers & Tractors: Won't cut grass

If the riding lawn mower runs but the blades won't cut the grass, the problem could be with the blade belt. Examine and replace the belt if you find it worn or broken. If the belt is okay, check the blade belt idler pulley, blade clutch cable and clutch lever assembly on tractors with manual blade actuators. On riding mowers that use a PTO switch to activate the blades, check the PTO switch and the electric clutch. Failed mandrel pulleys can also prevent the blades from spinning properly.

riding mowers & tractors

These repairs may help solve your riding mowers & tractors problem

Replace the riding mower blade belt

Replace the riding mower blade belt

The blade belt spins the blades to cut the grass. A worn or broken drive belt won't spin the cutting blades so your mower won't cut the grass. A worn blade belt can also cause mower deck vibration or uneven cuts. Examine the blade belt regularly and replace it if it's worn or broken.

How to replace the blade belt on a zero-turn riding mower

If the blades won't spin on a zero-turn riding mower, the problem could be a broken blade belt. Replace a broken or worn blade belt on a zero-turn riding lawn mower by following the steps in this DIY repair guide and video.

Repair difficulty
Time required
 30 minutes or less
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How to replace a riding lawn mower blade drive belt

If the blades on your riding lawn mower don’t spin fast enough—or don’t spin at all—the blade drive belt could be worn out or broken. This repair guide and video show how to replace a blade drive belt in less than an hour.

Repair difficulty
Time required
 45 minutes or less
Read more
Replace the riding mower mandrel assembly

Replace the riding mower mandrel assembly

The mandrel assembly attaches to the deck and spins the blade to cut grass. A blade won't move if the mandrel locks up. A damaged mandrel causes mower deck vibration and uneven cutting. Examine the mandrels regularly and replace any damaged mandrels.

How to replace a mandrel assembly on a riding lawn mower

If the blade shaft on your riding lawn mower vibrates or won't spin the blade, the mandrel might be worn or damaged. This DIY repair guide and vidoe explain how to replace a riding lawn mower mandrel assembly in just 6 steps.

Repair difficulty
Time required
 30 minutes or less
Read more
Replace the riding mower blade engagement lever

Replace the riding mower blade engagement lever

The blade engagement lever pulls the blade clutch cable to spin the blades when you shift the lever to the engaged position. The blades won't spin-read: cut grass-if if the lever breaks. If the blades don't spin, examine the lever and replace it if it's broken.

Replace the riding mower deck idler pulley

Replace the riding mower deck idler pulley

The deck idler pulley tightens the blade belt against the blade pulleys to spin the blades when you shift the blade engagement lever to engage the blades. You might need to replace the riding mower deck idler pulley if the blades don't spin. A worn idler pulley can also cause uneven cuts and mower deck vibration, so check the idler pulley if you notice these symptoms. Replace the deck idler pulley if it's worn or broken.

Replace the riding mower blade clutch cable

Replace the riding mower blade clutch cable

The blade clutch cable tightens the blade belt to spin the cutting blades when you shift the blade clutch lever to the engaged position. Blades won't spin when you push the engagement lever if the blade clutch cable is worn or broken. Examine the cable when the blades won't turn. Replace the blade clutch cable if you find it worn or broken.

How to replace a blade clutch cable on a riding lawn mower

If the blades don't spin on your riding lawn mower when you shift the lever, the blade clutch cable could be broken. You can replace a broken blade clutch cable in about half an hour, by following the steps in this DIY lawn tractor repair guide and video.

Repair difficulty
Time required
 30 minutes or less
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Replace the riding mower electric clutch

Replace the riding mower electric clutch

The electric clutch mounts to the engine crankshaft and controls the mower's cutting blades. The blades won't spin if the electric clutch is defective. Replace the electric clutch if it won't engage the blades when activated.

How to replace the electric clutch on a zero-turn riding mower

If the blades on your zero-turn riding mower won't engage, the electric clutch could be at fault. This DIY repair guide and video explain how to replace an electric clutch on a zero-turning riding lawn tractor.

Repair difficulty
Time required
 45 minutes or less
Read more
Symptoms common to all riding mowers & tractors

Choose a symptom to see related riding mower and lawn tractor repairs.

Main causes: dead battery, stale fuel, bad starter solenoid, ignition system problem, bad ignition interlock switch, clogged carburetor
Main causes: punctured tire or inner tube, leaky valve stem, damaged wheel rim
Main causes: damaged tie rods, bent or worn wheel spindle, worn front axle, damaged sector gear assembly
Main causes: faulty battery, bad alternator
Main causes: engine overfilled with oil, leaky head gasket or sump gasket, damaged carburetor seals, cracked fuel pump, broken fuel line
Main causes: damaged cutting blade, worn deck pulley, damaged mandrel pulley, loose fasteners on mower deck components
Main causes: worn or broken ground drive belt, bad seat switch, transaxle freewheel control engaged, transaxle failure, dirty carburetor
Main causes: shift lever needs adjustment, neutral control needs adjustment
Main causes: unlevel mower deck, dull or damaged cutting blades, worn mandrel pulleys, bent mower deck, engine needs tune up
Repair guides common to all riding mowers & tractors

These step-by-step repair guides will help you safely fix what’s broken on your riding mower or lawn tractor.

How to replace a mandrel assembly on a riding lawn mower

Replace the mandrel assembly if the blade shaft vibrates or doesn't spin.

Repair difficulty
Time required
 30 minutes or less
How to replace the air filter on a riding lawn mower

Get your mower running smoothly again by replacing the air filter—it's a quick job you can do yourself, following these steps.

Repair difficulty
Time required
 15 minutes or less
February 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower ignition switch

Get your mower started again by replacing the ignition switch—it's a quick job you can do by following these steps.

Repair difficulty
Time required
 15 minutes or less
Articles and videos common to all riding mowers & tractors

Use the advice and tips in these articles and videos to get the most out of your riding mower or lawn tractor.

December 1, 2017
Wiring schematic symbols explained video
By Sears PartsDirect staff

Learn some of the most common symbols found in a wiring diagram and what they mean.

May 1, 2017
Troubleshooting a riding lawn mower blown fuse video
By Sears PartsDirect staff

Test the ignition switch and wire harnesses to find the short.

March 1, 2016
How to level a riding lawn mower deck for an even cut video
By Sears PartsDirect staff

Mower not cutting the grass evenly? Your mower deck might be the problem.