It is often seen that there is a small tube connected to the intake pipe of the car near the throttle. What's the use? What's your name? Listen to others say it's refueling.

There is a small tube near the throttle connected to the intake pipe of the car. This pipe is called the crankcase ventilation pipe and is connected to the crankcase ventilation valve on the engine cylinder head.

This valve is called an oil-water separator, which filters the mixed gas in the crankcase, allows the oil to flow back into the engine, and pours the gas into the throttle through the hose for secondary combustion, thus improving fuel economy and reducing pollutant emissions.

Extended information 1. The ventilation cavity and breathing tube in the crankcase forced ventilation system are blocked, and the one-way valve on the breathing tube does not work well, resulting in the blowby gas not being discharged in time. When the positive crankcase pressure increases, the engine oil entering the combustion chamber increases, resulting in "burning engine oil". It is necessary to dredge the ventilation cavity and breathing tube and replace the one-way valve.

2. The diaphragm of the one-way valve in the oil return hole of the oil-gas separator is broken, the engine crankcase is communicated with the separation cavity of the oil-gas separator, and the oil mist directly enters the air intake system without passing through the oil-gas separation unit, resulting in "burning engine oil", so it is necessary to replace the diaphragm of the one-way valve.

3. The one-way valve spring is too elastic to open normally, and too much gas is sucked out of the crankcase, resulting in low negative pressure in the crankcase; One-way valve is not installed in the direction of reverse gas flow, and abnormal gas enters the crankcase, resulting in high positive pressure in the crankcase.

Baidu Encyclopedia-Crankcase Ventilation System