M11 Plus Series Engines Operation and Maintenance Manual – Engine Noise Excessive — Combustion Knocks

Engine is operating at low ambient temperature

Check the shutters and engine compartment air. Refer to Procedure 101-015 (Operating the Engine) in Section 1.

Ether starting aid is malfunctioning

Repair or replace the ether starting aids. Refer to the manufacturer’s instructions.

Fuel grade is not correct for the application or the fuel quality is poor

Operate the engine from a tank of high-quality fuel. Refer to Procedure 018-002 (Fuel Recommendations and Specifications) in Section V.