The working status of each cylinder of the diesel engine can be checked using the following methods during idling operation:
(1) Listening method: Use a stethoscope or metal rod near the injector body to listen to each cylinder. The normal sound is similar to the “dang-dang” sound of a metal bang. If there is only a continuous, sharp "ho ho" sound, then the fuel supply to the cylinder is insufficient or it did not catch fire in time. If the knocking noise is loud, it means that the fuel supply to the cylinder is insufficient. is too large or the fuel injection time is too early.
(2) Color observation method: When the diesel engine is operating normally, the color of the exhaust gas is light gray, and slightly darker when the load is heavy. If black gas is discharged, it means that the combustible gas is not completely burned. The blue smoke inindicates that the lubricating oil enters the cylinder and is burned. If white smoke is emitted, it means that there is water in the diesel engine, the combustible gas is not burned, and white smoke is emitted. If the exhaust continually emits abnormal smoke, this indicates that some cylinders are not functioning properly.
(3) Temperature detection method: In the initial stage after starting the diesel engine (the temperature of the exhaust pipe is very high after working for a while, it will burn you if you touch it with your hands). Touch the exhaust pipe temperature of each cylinder with your hands. The working status of each cylinder can be identified. If the exhaust temperature of each cylinder is higher than that of other cylinders, it means that the fuel supply to that cylinder is high; if the temperature is low, this ifmeans that the fuel supply to this cylinder is low, or there; there is no fuel injection, or there is incomplete combustion or no combustion after fuel injection.
(4) Pulse method: Pinch the high pressure oil pipe tightly with your hands and feel the pulse during fuel injection. The pulsation is low, the explosion sound is low, and the oil supply volume of the. the low temperature cylinder is small. Abnormal explosion noise and high temperature are caused by a drop in fuel injection pressure of the injector, poor atomization of fuel injection, or failure to ignite and complete combustion in time. The cylinder with large pulsation, loud bursting noise and high temperature will deliver a larger amount of oil. Low explosion noise and low temperature indicate that the injector hole or needle valve is coince.
(5) Oil cut-off method: In order to accurately determine which cylinder is defective, you can cut off the high-pressure oil pipe leading to the injector oil circuit one by one , then stop working to observe the changes in the working conditions of the diesel engine. When the oil circuit of a certain cylinder is cut off, if the speed and sound of the diesel engine do not change or little, it means that the cylinder is working normally. If the cylinder knocks intermittently and black smoke is emitted and the fault disappears after cutting off the oil circuit of a certain cylinder, it means that the fault lies in that cylinder.