原因 1.在一般情况下,低压油路中的燃油是靠本身重量,输油泵的抽压作用和喷油泵的吸力而流动的。在使用中,特别是当柴油机大负荷时,燃油路中完全可能出现局部位置的燃油压力低于大气压力的情况。此时,如果燃油系统中的管接头与油路直接相通的螺钉和连接处的垫片密封不严,空气即从这些部位进入油路。例如,输油泵螺塞垫片密封不严或手油泵密封胶 Reason 1. Under normal circumstances, the low-pressure oil in the fuel by its own weight, pump pumping pressure and the suction pump flow. In use, especially when the diesel engine is under heavy load, it is quite possible that the fuel pressure in the fuel rail will be lower than the atmospheric pressure at the local location. At this point, if the fuel system pipe fittings and oil directly connected to the screw and the gasket gasket connection is not tight, air that is from these parts into the oil. For example, the oil pump screw gasket gasket is not tight or hand pump sealant