What causes a mechanical knocking sound in a Toro Engine?
- JJames BarberSep 12, 2025
If your Toro Engine is producing a mechanical knocking sound, it could be due to a loose blade (mower only); inspect and tighten the blade nut to the correct torque. A loose flywheel can also cause knocking; inspect and tighten the flywheel nut to the correct torque. Pre-ignition can also result in a knocking sound; see the “Engine Pre-Ignites” table. A loose rod cap can also cause knocking; replace the rod and bearings. Finally, loose engine mounting bolts can contribute to the noise; tighten the bolts.






