Loud knocking or metallic banging noise from engine while running

Safety first: Immediately shut down the generator if a loud knock develops to prevent catastrophic failure.

• Check oil level: Verify oil is at the correct level. If very low, top up but be aware internal damage may already exist.
• Inspect flywheel: Remove the flywheel cover and check that the flywheel nut is tight and the key is intact. Tighten to the torque specified by Scheppach.
• Listen for location: Use a mechanic's stethoscope to localize the noise (top end vs. bottom end). Persistent deep knocking usually indicates bearing or rod damage.
• Do not continue running: If internal damage is suspected, stop using the generator and arrange for engine overhaul or replacement.