Riding Lawn Mower support

Usually, the primary cause for this is that the engine is low on oil.

1
Check the oil dipstick, and fill to the full mark, being careful not to overfill. Refer to the operator's manual for details.

2
Check all of the loose components (i.e. muffler, carburetor, flywheel screen, spark plug and wires, crankshaft pulleys, etc.) and tighten if needed.

Abnormal knocking sounds can be a sign of engine trouble. A knocking engine needs service attention as soon as possible. Contact your local authorized service center for expert assistance in resolving this issue.