Diesel engine injector nozzle needle is burned in use, which is a common failure phenomenon.
The phenomenon of "burning death" of the injection nozzle needle valve:
There is no change in the diesel engine when the diesel engine is screwing or loosing the pressure adjusting screw on the fuel injector. In addition, the performance of the diesel engine is not exactly the same because the position of the injector needle valve "burned" is different.
When the needle valve is "burned" in the open state (injecting oil), there will be a metal knocking without a certain rhythm in the cylinder of the work. At the same time, the exhaust pipe will make a "snap, crack" sound, exhaust smoke and white smoke. The temperature of the high-pressure oil pipe and the exhaust pipe of the injector is also higher than that of the other cylinders. At this time, when the oil is checked, the sound of knocking and the exhaust smoke and smoke are made. The phenomenon disappeared and oil and gas were discharged from the high pressure tubing loosened.
The cylinder will not work when the needle valve is "burned" in the closed state (that is, no fuel injection). Therefore, the temperature of the injector and exhaust pipe at the position of the cylinder is lower than that of the other cylinders. There is no change in the work of the diesel engine when the oil is checked. It is only injected from the high pressure tubing and does not exhaust.
From the injection nozzle needle valve of "burning dead", it is observed that the original bright surface of the guiding part will be burned mostly, and it is blue or blue purple. Thus, it is known that the local heating of the nozzle is the main reason for the needle valve "burning dead" in the needle valve. Carbon deposition causes the sealing of the seat surface to be damaged, and the nozzle is overheated, causing needle valve movement to block and diesel atomization to be bad. Finally, the nozzle is sintered and stuck.
After the injector is "burned", it is not necessarily all discarded, and after the needle valve is taken out with the clean oil to be lapped properly, it can still continue to use. However, the needle valve should not be turned into blue at this time. Otherwise, the needle valve has been annealed and should be replaced. It should not be used reluctantly, otherwise the diesel engine will be deteriorated.
Common causes of diesel engine fuel injection needle valve burn are:
1 incorrect assembly methods.
In order to prevent rust in transportation and storage, the new nozzle is coated with a layer of antirust oil. When replacing the nozzle, if the oil is not cleaned in time before installation, it will lead to the "burn" of the nozzle needle valve. The reason is that the antirust oil in the nozzle is easy to stick to the pin valve in high temperature.
The fuel nozzle leaks diesel. When the end face of the nozzle is dampness because of the leakage of diesel oil, it may cause the surface combustion. The heat of the combustion will directly affect the nozzle and cause "burn death".
3. When the injector is installed, the washer dirty, or the asbestos rope and other adiabatic materials instead of the copper washer, affect the heat dissipation of the nozzle, so that the steering part of the precise injection nozzle needle valve leads to the inflexibility of the needle valve movement. In addition, the installation of the skew causes the leakage of the bureaus, the uneven heat and the "burning of the nozzle needle valve". The cause of the leakage of the nozzle installation hole is mainly due to uneven washers, loss of elasticity, uneven installation holes or carbon deposition and impurities.
(4) when the injector is assembled, the tightening torque of the fastening screw sleeve of the nozzle is too large, causing the needle valve body to be easily deformed, and the needle valve is stuck, especially the long type porous nozzle is more easily "burned".
When the injector is installed in the injector hole of the cylinder head, the gap is too small to fit too tight, and some even knock in. In this way, when the temperature of the diesel engine is high, the original minimum clearance of the needle valve parts is damaged, and the relative movement of the needle valve and the needle valve body produces a larger friction force, that is, it may cause the injector nozzle to "burn to death".
2 the diesel oil road has too much impurity particles in the diesel oil, most of which are an important cause of the "burn death" of the nozzle. The diesel filter used by the diesel engine can filter out the impurity more than 0.005mm, obviously the filtration ability is not strong. If the filter core is broken and the filter core is on the bottom mat Leakage or damage, part of the diesel directly into the fuel injection pump, dirt into the nozzle, that is likely to make the nozzle needle stuck "burn".
490 diesel engine and some other diesel engines are equipped with metal rod type injector filter core (filter needle) in the nozzle of the injector. Practice has proved that the device has good filtering effect. But if the device is missing for some reason in the maintenance process, the injection nozzle needle valve will be "burnt to death" quickly.
4125 diesel engine, such as no fuel injector, will not only waste diesel oil, but also make the dirty things into the injector (especially when the diesel engine stops working), through the pressure spring, tappet and even the nozzle needle valve of the injector, so that the needle valve is "burnt to death".
In addition, in the installation of high pressure oil pipe, it is generally to take the oil end first, and then put the oil valve in the maximum position, so that the fuel injection pump supply oil until the oil pipe of the high pressure oil pipe is injected 2~4 times, and then connect with the injector. Otherwise, because the accumulating in the oil pipe joint and the high pressure oil pipe is not washed out, it is easy to make the injection nozzle needle valve "burn to death".
3 oil supply time is often too late when the injector is injecting to the cylinder, it starts to burn, and the pressure of the eruption is immediately followed by the gas of the nozzle needle valve, causing serious back gas accumulation and thus killing the needle valve.
