How serious is the engine knocking sound issue?

[MacHaley]

The problem is very serious and requires immediate inspection at a repair facility. Below is an introduction to engine knocking: 1. Definition: Engine knocking is a phenomenon where a metallic knocking sound occurs when the pressure rise rate in the cylinder is too high. Knocking is categorized into combustion knocking and mechanical knocking. A sharp metallic knocking sound near the top dead center due to combustion reasons is called combustion knocking or hot knocking. A dull knocking or friction sound caused by abnormal clearances in moving parts and bearings is called mechanical knocking or cold knocking. 2. Causes: Poor lubrication conditions, low oil pressure or excessively low oil viscosity, inadequate splash lubrication on the cylinder walls, failure to form a normal oil film between the piston and cylinder wall, leading to direct contact between the piston and cylinder, resulting in knocking.