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The Function and Maintenance of Diesel Engine Crankcase Breathing Pipe

2021-07-29

Diesel engines are equipped with crankcase ventilation pipes, commonly known as respirators or vents, which can make the cavity of the crankcase communicate with the atmosphere, reduce fuel consumption, reduce failures, and ensure good working performance. When the engine is working, the gas in the cylinder will inevitably leak into the crankcase, and the leakage of the cylinder liner, piston, piston ring and other parts will become more serious after wear. After the gas leaks into the crankcase, the gas pressure in the crankcase will increase, causing the oil to leak out at the joint surface of the engine body and the oil pan and the oil gauge hole. In addition, the leaked gas contains sulfur dioxide, and the temperature is high, which will accelerate the deterioration of the engine oil. Especially in a single-cylinder engine, when the piston descends, the gas in the crankcase is compressed, which causes resistance to the movement of the piston.

Therefore, the function of the crankcase breather pipe can be summarized as: prevent engine oil deterioration; prevent leakage of crankshaft oil seal and crankcase gasket; prevent body parts from being corroded; prevent various oil vapors from polluting the atmosphere. In actual use, it is inevitable that the ventilation pipe will be blocked. To keep it unblocked, regular maintenance work must be required. In the general working environment, every 100h can be a maintenance cycle; working in a harsh environment with more dust in the air, a maintenance cycle should be 8-10h.

The specific maintenance methods are as follows: (1) Check the pipeline for flattening, damage, leakage, etc., and then clean it and blow it with compressed air. (2) For the crankcase ventilation device equipped with a one-way valve, it is necessary to focus on inspection. If the one-way valve is stuck and has not been opened or blocked, the normal ventilation of the crankcase cannot be guaranteed and must be cleaned. (3) Check the vacuum of the valve. Unscrew the one-way valve on the engine, then connect the ventilation hose, and run the engine at idle speed. Put your finger on the open end of the one-way valve. At this time, your finger should feel a vacuum. If you lift your finger, the valve port should have a "Pop "Pap" suction sound; if there is no sense of vacuum or noise in your fingers, you should clean the one-way valve and vent hose.