After the diesel engine runs for a long time, due to parts wear or improper operation, adjustment, maintenance is not timely and other reasons, there will often be insufficient power problems. The causes of insufficient power of diesel engine are more complex, but the main reasons are two aspects: first, due to poor combustion chamber seal, insufficient oil supply, poor atomization of injector, insufficient gas supply, improper adjustment of fuel supply timing and other reasons, resulting in incomplete combustion of fuel, resulting in insufficient power of diesel engine; Second, due to excessive wear, poor lubrication, poor cooling, improper installation and other reasons, the friction loss of the diesel engine itself is too large, so that the output power is reduced, resulting in insufficient power of the diesel engine. Therefore, when analyzing and eliminating the failure of insufficient power of diesel engine, the two key issues of combustion quality and friction loss should be seized, and then combined with the understanding and mastery of the wear situation and technical status of the various parts of the diesel engine, so as to find out the reasons for the greatest possibility of insufficient power of diesel engine, and then check and eliminate. The main reasons for the lack of diesel engine power are as follows:
First, the intake and exhaust system is not smooth
Diesel engine air filter and intake due to too much dust and not smooth or blocked, will make the amount of air into the cylinder is insufficient, not only resulting in insufficient compression pressure, but also because the fuel can not get enough air and can not be completely burned, resulting in insufficient diesel engine power. Under normal conditions, if the exhaust pipe or muffler accumulates a large amount of carbon, the exhaust is not smooth, so that the exhaust gas in the cylinder is not clean, and the amount of fresh air entering the cylinder will also be reduced. At this time, although the compression pressure is not low, due to the insufficient amount of air entering the cylinder, the fuel can not be completely burned, resulting in insufficient power of the diesel engine and black smoke. Therefore, the user should regularly remove the dust in the air filter and inlet, and regularly remove the carbon and dirt in the exhaust pipe and muffler to ensure the smooth flow of the intake and exhaust system.
Two, the intake and exhaust system is not sealed
The turbocharged diesel engine relies on the exhaust pressure to blow the turbine, which drives the pump wheel to rotate at high speed, and delivers compressed air to the intake pipe, so as to ensure the diesel engine output greater power. Therefore, the intake and exhaust systems of supercharged diesel engines must be completely sealed. If the exhaust pipe or joint leaks, the exhaust pressure will be reduced, the supercharger speed will be reduced, and the intake pressure will be reduced, resulting in a decrease in the diesel engine power. If the intake system (including the intake port, intercooler and the joints) leaks, then although the intake pressure provided by the supercharger meets the standard, the real amount of air entering the cylinder will be obviously insufficient, so that the diesel engine power will be reduced. This failure also often occurs after repair and maintenance, especially after the re-assembly of the intake and exhaust systems, due to various reasons, the seal is not tight.
Third, the compression pressure in the cylinder is insufficient
Diesel fuel injector installation hole leakage or copper gasket damage, cylinder gasket leakage, valve, valve seat, cylinder liner, piston, piston ring wear is too large, valve clearance is too small, pressure reduction mechanism clearance is too small and other reasons, will cause the combustion chamber seal is poor, so that fresh air into the cylinder leaks out from these parts, resulting in insufficient air in the cylinder. The fuel can not get enough air in the combustion chamber and can not be completely burned, and the power of the diesel engine is naturally reduced, resulting in insufficient power. At the same time, due to the insufficient amount of air in the cylinder, the pressure and temperature of the compression end point must be reduced, so that the combustion process of the fuel is delayed backward, resulting in the occurrence of post-combustion phenomenon, so that some fuel can not be completely burned and discharged with the exhaust gas. In addition, high temperature and high pressure gas will also leak out from the above parts, reducing the ability of gas to do work, resulting in insufficient power of the diesel engine. Another characteristic of diesel engine underpower is black smoke. Therefore, the insufficient compression pressure in the cylinder is one of the main reasons for the insufficient power of the diesel engine, and should be eliminated in time once it occurs.
Four, the turbocharger is not working well
Turbocharger is the key component that affects the power of diesel engine. If the supercharger burns out, it will cause its speed to drop, and the intake pressure to drop, resulting in the diesel engine power reduction. The sign of early damage to the supercharger is "oil discharge", that is, to the exhaust pipe and intake pipe oil discharge, when the oil discharge is serious, the supercharger has tended to be damaged. The axial and radial clearance of the rotor of the supercharger must be guaranteed within the specified range. Diesel engines equipped with superchargers should be noted in use, after starting to idle for a few minutes, after the oil has been recycled to accelerate and load, especially the first start every day should pay attention to. After the diesel engine flameout, it should also idle for a few minutes, and then flameout after the diesel engine and supercharger speed decline. The habit of blasting the throttle before extinguishing is a fatal blow to the life of the supercharger, because the two-foot throttle before extinguishing is blasted, the speed of the supercharger is immediately increased, at this time the diesel engine suddenly flares out, the oil pump stops running and stops the oil supply, the supercharger continues to rotate at high speed under poor lubrication conditions to produce dry grinding, so that the rotor shaft and bearing accelerate wear, the sealing ring is strained and the oil is discharged. In severe cases, the turbine will be burned and the rotor shaft will be broken.
Five, the injection pump oil supply time is improper
Due to the improper adjustment of the fuel supply timing of the diesel fuel injection pump, excessive wear of the fuel injection pump and other reasons, it will cause the fuel supply timing of the fuel injection pump to be too late, thus delaying the entire combustion process, which is usually called
"Afterburn." At this time, some of the fuel is not fully burned before being discharged from the cylinder, so that the energy of the fuel can not be fully utilized and utilized, resulting in insufficient diesel engine power, resulting in black smoke of the diesel engine, parts heating, exhaust temperature is too high, and the exhaust pipe will spark when serious. At this time, the oil supply timing should be checked and adjusted. If the plunger pair and the oil outlet valve pair wear too much, they should be repaired or replaced in time.
Six, the fuel injector injection performance is poor
Diesel injector needle valve stuck, injection hole blockage or fragmentation, injector spring break or elastic disappearance, injector spring adjustment is too tight or too loose, plunger pair, oil valve pair, needle valve pair wear is too large, fuel system low pressure oil circuit blockage and other reasons, will cause the injector atomization poor or dripping oil and other conditions, so that fuel combustion is incomplete, resulting in diesel engine power decline. At this time, the main feature of the diesel engine is black smoke, which should be repaired or replaced in time.
7. Insufficient fuel supply in the fuel system
The problem of insufficient fuel supply in the fuel system has two aspects: "blocking" and "leaking". The so-called "blocking" is due to long-term non-maintenance, resulting in diesel filters and pipelines being partially blocked by dirt, so that the oil supply resistance increases and the oil supply is not smooth. If the diesel engine in the case of small load and less oil, the oil supply can also meet the requirements, but in the case of large load and large oil, the oil supply can not meet the requirements, resulting in the diesel engine power decline. Therefore, in order to ensure that the oil supply system is smooth, it must be maintained according to the regulations. The so-called "leakage" is the leakage of low-pressure oil from the fuel tank to the supply pump. Similarly, in the case of small load and less oil supply is enough, in the case of large load and large oil quantity, due to air leakage, the low-pressure oil circuit inhales air, resulting in insufficient oil supply, resulting in insufficient diesel engine power failure. "Leakage" often appears after repair and maintenance, in the maintenance of the disassembly of the diesel filter and pipeline, assembly if the joint seal is not tight or the filter installation sealing ring is not tight, it will cause "leakage" failure.
At the same time, the plunger pair of the injection pump or the oil outlet valve pair is too worn, the nozzle hole is blocked, the needle valve is stuck and other reasons, so that the fuel supply of the injection pump is insufficient, can not meet the requirements of the diesel engine load increase, but also lead to the diesel engine power shortage. The resulting lack of power will not cause damage to diesel engine parts, users will feel that the diesel engine is weak, the speed cannot be increased, and the temperature and exhaust temperature of the heated parts are low. If such a situation is found, the reasons for insufficient oil supply should be checked and eliminated in time.
Eight, the governor is working badly
Diesel governor due to improper assembly adjustment, governor spring pressure is too tight or broken, weak elasticity and other reasons, so that the power of the governor to promote the fuel injection pump rack movement is too small, resulting in the fuel injection pump is difficult to increase the amount of fuel, but also cause the diesel engine power shortage. In this case, the obvious characteristic of the diesel engine is that the acceleration is more difficult and the speed rises slowly; Deceleration is relatively easy, speed reduction is faster, and the speed of the diesel engine is unstable. The spring of the governor should be checked, adjusted or replaced at this time. In addition, if the power of the diesel engine does not change significantly, but does not go up from the maximum speed observed by the engine tachometer on the instrument panel, then it is generally caused by the slack of the generator belt. Because some diesel engine tachometer is connected to the tachometer by the generator all the way to the fire line, the detected is the speed of the generator, after the conversion of the pulley speed ratio, the engine speed is marked on the instrument. Therefore, the slack belt will cause the engine speed indication error. This failure should not be mistaken for a failure of insufficient engine power, tighten the generator belt, the fault will be solved. When the generator assembly needs to be replaced for maintenance, it should be noted that the replacement of the new generator pulley diameter should be the same as the old generator, otherwise it will also cause the illusion of engine speed indication error.
Nine, lubrication and cooling system is not working well
Due to the failure of the diesel engine lubrication system, resulting in insufficient or interrupted oil, too dirty oil, with too large or too small clearance, diesel engine overheating and other reasons, so that the relative movement of the parts of poor lubrication, it will increase the friction loss of power, resulting in the reduction of diesel engine output power, when the diesel engine occurs burning tile or cylinder accident, friction loss of power increases sharply. The output power of the diesel engine decreases sharply, which will cause the diesel engine to stop by itself. The lack of power of diesel engine due to poor lubrication has several obvious characteristics. That is, the diesel engine parts heat up, the oil temperature rises, and the smell of oil coke can be smelled when it is serious, and the diesel engine makes an abnormal dull sound. At this time, the load of the diesel engine should be reduced or removed to make it run empty at low speed in order to find the cause for elimination. At the same time, if the crankcase oil is too much, so that the oil level is too high, the movement resistance of the crank connecting rod mechanism increases, the power consumption increases, and the diesel engine power is insufficient.
In addition, the diesel engine due to excessive overload, running time is too long, coolant flow is insufficient or interrupted and other reasons, resulting in the working temperature of the diesel engine is too high, will also reduce the amount of air into the cylinder, resulting in fuel can not be completely burned, the power of the diesel engine is reduced, resulting in insufficient power. When the temperature of the diesel engine is too high, the radiator and pipeline should be checked to remove scale.