Symptoms
- Self-propel or blade drive suddenly stopped working
- Belt visible as broken or hanging loose under the deck/chassis
- May have heard a snap or squeal before it failed
- Worked fine until recently, or belt looked worn beforehand
Likely causes
- CommonBelt worn out from age and useRubber belts stretch, crack, and eventually snap after years of friction and heat cycling.
- PossibleBelt caught on debris or a foreign objectA stick or debris caught in the belt path can force it off track or snap it.
- PossiblePulley misalignment causing premature wearA bent or misaligned pulley can wear through a belt faster than normal.
- PossibleBelt tensioner spring failureA broken tensioner can let the belt run loose and slip off or wear unevenly.
What to do
- Disconnect the spark plug wire before inspecting or working near the belt.
- Locate the belt routing diagram, often on a sticker under the deck or in the owner's manual.
- Remove the broken belt and inspect the pulleys and tensioner for damage or debris.
- Install the new belt following the exact routing diagram, making sure it seats properly in each pulley groove.
- Check the tensioner spring engages correctly to keep proper belt tension.
- Test the self-propel or blade engagement carefully before resuming normal mowing.
Tools and parts
- Wrench set
- Belt routing diagram
Mower drive beltSearch: “lawn mower drive belt replacement”
When to call a pro
If you can't locate the correct routing diagram or the pulleys look damaged, a mower shop can replace the belt correctly.
Safety
Use caution
Disconnect the spark plug wire before reaching near pulleys or the belt path.