Symptoms
- Squealing noise, especially under load
- Blades or drive wheels feel weaker than usual
- Burning rubber smell while mowing
- Visible belt wear, cracking, or shiny glazed surface
Likely causes
- CommonWorn or glazed beltBelts harden and lose grip with age and heat exposure, causing slipping.
- CommonIncorrect belt tensionA belt not tensioned to spec, or a tensioner spring that's weakened, won't grip properly.
- PossibleMisaligned pulleyA bent or shifted pulley can cause the belt to ride unevenly and slip.
- PossibleOil or grease contamination on the beltA leaking seal or over-greased pulley can coat the belt and reduce friction.
What to do
- Turn off the engine and inspect the belt for cracking, fraying, or a glazed, shiny surface.
- Check the belt tensioner spring and pulley for proper tension per the owner's manual.
- Look for oil or grease near the belt path, and clean or address the source of any leak.
- Check pulleys for wobble or visible misalignment as the belt runs.
- Replace the belt if it shows wear, using the exact size and type specified for your model.
- Test run after replacement, watching and listening for continued slipping.
Tools and parts
- Wrench set
- Tension gauge (if specified)
Riding mower drive beltSearch: “riding mower drive belt”
Riding mower deck beltSearch: “riding mower deck belt”
When to call a pro
If pulleys are misaligned or bent, a small engine shop can true or replace them along with the belt.
Safety
Use caution
Always shut off the engine and remove the key before working near belts or pulleys.