January 1, 2015

How to replace a riding lawn mower blade drive belt

By Lyle Weischwill
How to replace a riding lawn mower blade drive belt

This DIY riding mower repair guide gives step-by-step instructions for replacing a blade drive belt on a riding lawn mower. The blade drive belt connects the engine pulley to the mower deck pulleys and spins the cutting blades. A worn blade belt won't spin the blades fast enough to cut the grass. A broken blade belt won't spin the blades at all. Examine the blade drive belt and replace it with a manufacturer-approved replacement part if you find damage or excessive wear.

Use this procedure to replace the blade drive belt on Craftsman, MTD, Husqvarna, Murray, Toro, Troybilt, Poulan and Snapper riding lawn mowers and lawn tractors.

Quick links
Tools required
Pliers
Work gloves
Repair difficulty
Time required
45 minutes or less
Repair difficulty
Time required
45 minutes or less
Replacing a blade drive belt on a riding lawn mower

This video explains how to replace the blade drive belt on a riding lawn mower.

Instructions

  1. 01.

    Disconnect the spark plug

    Park the tractor on a level surface and set the parking brake.

    Turn the ignition switch off and remove the key.

    Wear work gloves to protect your hands.

    Lift the tractor hood and disconnect the spark plug wire.

    Tip: Disconnect both spark plug wires if your tractor has 2 cylinders.
    Disconnect the spark plug.

    Disconnect the spark plug.

  2. 02.

    Pull off the mower deck

    Lower the mower deck to its lowest position.

    Disengage the cutting blades.

    Roll the blade belt off the engine pulley and release the belt from the belt keepers.

    Remove the front lift link support retaining pin and washer, and then detach the support from the deck.

    Remove the left suspension arm retaining clip and washer. Then detach the arm from the tractor frame.

    Remove the left rear deck bracket retaining clip and washer. Then release the bracket from the deck.

    Repeat the process on the other side of the deck to disconnect the right suspension arm and right rear deck bracket.

    Pull the deck out far enough to access the blade drive belt.

    Warning: After you disconnect the rear lift links, the spring-loaded attachment lift lever exerts more tension on the lever so don't use the lever until you reinstall the mower deck.
    Pull out the mower deck.

    Pull out the mower deck.

  3. 03.

    Remove the old blade drive belt

    If the belt is still intact, note the routing of the blade belt through the pulleys and belt keepers.

    If the belt is broken, refer to the belt routing sticker on the deck or your owner's manual for guidance.

    Release the belt from the idler pulleys, belt keepers and mandrel pulleys.

    Pull the belt off the mower deck.

    Tip: Take a photo of the belt routing to refer to when you install the new belt.
    Remove the old blade drive belt.

    Remove the old blade drive belt.

  4. 04.

    Install the new blade drive belt

    Loop the new belt around both mandrel pulleys.

    Route the belt through the idler pulleys and belt keepers.

    Install the new belt.

    Install the new belt.

  5. 05.

    Reinstall the mower deck

    Push the deck under the tractor frame.

    Reconnect the front lift link support to the deck with the washer and retaining clip.

    Reconnect the left suspension arm and deck bracket with the washers and retaining clips.

    Repeat the process to reconnect the right suspension arm and deck bracket.

    Route the blade belt through the belt keepers and roll the blade belt onto the engine pulley.

    Reinstall the mower deck.

    Reinstall the mower deck.

  6. 06.

    Reconnect the spark plug

    Reconnect the spark plug wire and lower the tractor hood.

    Tip: Reconnect both spark plug wires if your engine has 2 cylinders.
Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.

Symptoms common to all riding mowers & tractors

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

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

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 the starter motor on a riding lawn mower

If you hear the solenoid click but don’t hear the starter motor spin when you turn the key, follow these steps to replace it.

Repair difficulty
Time required
 30 minutes or less
January 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower spark plug

If the engine is hard to start or if the spark plug electrode is burnt or cracked, take 15 minutes to replace it.

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

If the engine of your lawn tractor surges or is hard to start, the carburetor could be the problem. Follow these steps to install a new one.

Repair difficulty
Time required
 45 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.

May 1, 2017

Riding lawn mower engine spins but won't start video

By Sears PartsDirect staff

Troubleshoot fuel, spark and compression issues.

June 1, 2016

How to mow a lawn for healthier grass

By Erin Hynes

How often and tall you mow your lawn has a big impact on its health. Check out these 3 rules.

March 1, 2016

How to change the Smart Switch Ignition password on a lawn tractor video

By Sears PartsDirect staff

See how to unlock the factory default start code so you can set your own passcode.