Abnormal sound of Cruze engine "da da da"

The typical valve noise is loud when the cold car starts because the oil temperature is not enough and the viscosity can't meet the requirements, so the noise will be loud if the lubrication is not enough. After the temperature rises, the oil viscosity becomes better and the natural noise becomes smaller, which is normal.

Nowadays, cars use hydraulic jacking cylinders, which can adjust the valve clearance according to the oil pressure. When the oil temperature comes up and the pressure meets the requirements, it will adjust itself, which is the reason for the sound reduction.

Extended data:

The function of the valve is specially responsible for inputting air into the engine and discharging exhaust gas after combustion. From the engine structure, it can be divided into intake valve and exhaust valve. The function of the intake valve is to draw air into the engine and mix it with fuel for combustion; The function of the exhaust valve is to exhaust the exhaust gas after combustion and dissipate heat.

References:

Valve _ Baidu Encyclopedia