The premise of correct treatment is to distinguish the type and cause of abnormal sound. The abnormal sound caused by the fuel system is mostly sudden, and the mechanical abnormal sound is generally gradual (except for sudden damage of the machine parts); for the four stroke internal combustion engine, the piston should go up and down two times to do one work, because the abnormal sound caused by the fuel system is abnormal sound than the mechanical abnormal sound. Half of the sound is less; the different mechanical abnormal sound corresponds to a specific speed, and the abnormal sound of the fuel system does not have this characteristic; in addition, the characteristics of the abnormal sound can be distinguished, and the mechanical abnormal sound (such as the gap between the connecting rod journal and bearing, the piston pin hole and the piston pin, the piston and cylinder sleeve) is too large. The sound of the rhythm, as long as the diesel engine operates at a specific speed, does not disappear. And the abnormal sound caused by the fuel supply system is not a single sound, and the duration is short (because most of the diesel starts to burn), the noise is generally crisp and clear.
The correct way to distinguish the abnormal noise from the engine is caused by the mechanical fault of the diesel engine or the fault of the fuel system.
The abnormal sound of different machinery or machine parts of the diesel engine corresponds to a certain speed, such as the idle piston knocking; the idle speed is slightly higher than the piston pin; the medium speed connecting rod bearing is ringing; the middle and high speed is the crankshaft bearing. And the abnormal sound failure of the fuel system has no characteristics, for example, when the oil supply front angle is too big, there is an obvious knocking sound when speeding up; When the oil advance angle is too small, the diesel engine is not running smoothly and has the feeling of "dull", the operation is unstable, the exhaust is black smoke, the single cylinder oil supply is over hourly, the diesel engine is unstable and vibrates.
Unscrewing the high pressure oil pipe on the injector respectively, if the abnormal sound disappears, it indicates that there is a mechanical abnormal sound fault; if the abnormal sound is weakened and does not discharge black smoke, it is an abnormal sound of the fuel system; if the diesel engine is unstable, the sound of the noise is obvious at the injector, and the abnormal sound of the oil is broken to a certain cylinder when the clearance is normal and the abnormal sound disappears when the oil is broken to a cylinder. The needle valve of the injector is stuck to death.
If the abnormal sound is not detected by the method of oil breaking, and the abnormal sound belongs to the rough knocking sound, it can be judged to be related to the injection time too early. It can check whether the fuel supply of the fuel injection pump is accurate and the interval of each cylinder is consistent. Generally speaking, if the oil pump side cover is opened, the lock nut of the bolt tappet is found not. When the oil supply is loose, the oil supply time of each cylinder will not be too far away and must be corrected. The adjustment of the timing of the oil supply has a significant influence on the abnormal sound. When the adjustment is adjusted, the sound of the cylinder and the exhaust are basically normal. If the time of oil supply is too late, there will be a lot of black smoke, although there is no sound of the knocking.
If the oil supply is adjusted in positive time, the abnormal sound can not be ruled out. It may be related to the serious imbalance of the supply of oil. The vehicle should be checked for the oil supply of each cylinder. If the oil supply is not evenly distributed, the injection pump should be removed and sent out.
If the weather is cold or after the start of the abnormal sound, the cylinder has a piston knocking phenomenon in a cylinder, and the slight piston knocking is generally not dealt with.
The diesel engine has just started. If there is an abnormal sound, you can feel the temperature of the exhaust manifold by the finger. The high temperature of the cylinder is too large. In addition, the poor quality of the fuel can cause abnormal sound. If the driver knows that the fuel quality is poor, it is not necessary to find the diesel engine fault, only need to replace the fuel.
