(1) When cold start, the generator set starts to work overload without preheating
When the diesel generator set for cold start, due to the high viscosity of oil, poor liquidity, oil pump oil supply is insufficient, because of the lack of oil lubrication, the friction surface of the machine will also be lack of oil lubrication and serious wear, and even lead to cylinder pumping, burning tile and other failures. Therefore, when the diesel engine is started after cooling, it should be heated by idle running, and then run with load when the temperature of standby oil reaches above 40℃. The engine should be started from a low gear and driven in each gear in order for a certain mileage until the oil temperature is normal and the fuel supply is sufficient, then it can be switched to normal operation.
(2) When the diesel generator set runs with insufficient oil
Due to insufficient oil lubrication, the supply of oil lubrication to each frictional sub-surface is also insufficient, resulting in abnormal wear or burnout. Therefore, before starting and during operation of diesel engines, it is necessary to ensure sufficient oil quantity to prevent cylinder extraction and tile burning and other failures due to lack of oil.
(3) Stopping with load or stopping after sudden unloading of load
After diesel engine shutdown, the cooling system water circulation stops, the cooling capacity decreases sharply, and the heating parts lose cooling, which will easily lead to cylinder head, cylinder liner, cylinder block and other parts overheating, producing cracks, or making the piston over-expand and stuck in the cylinder liner. On the other hand, if the diesel engine is shut down at idle, the friction surface will not contain enough oil, and when the diesel engine is restarted, the wear will increase due to poor lubrication. Therefore, the load should be unloaded before the diesel engine is shut down and gradually decelerated and run without load for a few minutes.
(4) When the diesel engine is cold start, step on the accelerator to accelerate
If you step on the throttle, the speed of the diesel engine will rise sharply, which will lead to some friction surfaces on the engine due to dry wear and serious wear. In addition, when the throttle is pressed to the bottom, the force on the piston, connecting rod and crankshaft will change greatly, leading to serious shocks and easy damage to parts.
(5) Running a diesel engine with insufficient cooling water or excessive cooling water and oil temperature can cause serious problems.
If the diesel engine doesn’t have enough cooling water, it won’t be able to cool down effectively, which can cause it to overheat. Similarly, if the cooling water and oil temperature is too high, it can also cause the diesel engine to overheat. When this happens, the cylinder head, cylinder liner, piston assembly, and valve are subjected to a large thermal load, which can cause their mechanical properties, such as strength and toughness, to decline sharply. This can lead to increased deformation of the parts, reduced matching gaps between parts, and accelerated wear of the parts. In addition, cracks and failures can occur in the parts.
Excessive cooling water and oil temperature can also cause problems. It can accelerate the aging, deterioration, and burning of the oil, which can cause the viscosity of the oil to decrease. This can lead to deteriorating lubrication conditions for the sleeve, piston, and main friction pairs, which can result in abnormal wear. Overheating of the diesel engine can also affect the combustion process, causing problems such as malfunctioning injectors, poor atomization, and increased carbon deposition. Therefore, it is important to ensure that the diesel engine has sufficient cooling water and that the cooling water and oil temperature is kept within the recommended range to avoid these problems.
(6) During the operation of the diesel engine when the cooling water and oil temperature are too low
the cylinder wall temperature decreases, causing water vapor generated by combustion to condense into water droplets. These droplets then come into contact with the exhaust gas, generating acid substances that attach to the cylinder wall and cause corrosion and wear. Studies have shown that when a diesel engine is frequently operated at a cooling water temperature of 40°C to 50°C, the wear and tear on its parts is several times greater than that under normal operating temperatures (85°C to 95°C). When the water temperature is too low, the temperature in the cylinder is also low, which prolongs the ignition delay period of the diesel engine. Once the fire is on, the pressure rises rapidly, causing the diesel engine fuel to be rough and potentially causing mechanical damage to the parts. If the diesel engine continues to run at a low temperature of the cooling water for an extended period, the gap between the piston and the cylinder liner may increase, leading to cylinder knocking and vibration, and potentially causing cavitation in the cylinder liner. Additionally, if the oil temperature is too low, the oil viscosity increases, fluidity decreases, and the oil quantity in the lubricating part may be insufficient, leading to poor lubrication, increased friction pair wear, and a shortened service life for the diesel engine.
(7) Operating with low oil pressure
If the oil pressure is too low, the lubricating oil cannot circulate normally and provide sufficient pressure for lubrication. This can result in insufficient oil reaching the lubricated parts. Therefore, when operating the machine, it is important to monitor the oil pressure gauge and oil pressure indicator. If the oil pressure is lower than the specified level, the machine should be immediately stopped, troubleshooting should be conducted, and then the machine can be restarted.
(8)The machine runs over speed and over load
If the diesel engine will run under the working condition of excessive load and high speed, it is easy to cause the thermal load and mechanical load of cylinder liner, piston, connecting rod and other parts to increase, and it is easy to pull cylinder, burning tile and other faults. Often overload operation, resulting in a long time of rough combustion in the cylinder, easy to damage the cylinder pad.
(9) Increase the accelerator before turn off the engine
If the diesel engine in high-speed operation stops running suddenly, its huge inertia is easy to cause crank connecting rod mechanism and valve mechanism and other parts to be damaged, shorten the service life of machinery. Slamming the throttle can cause too much fuel to enter the cylinder to fully burn, and the excess fuel can run down the cylinder walls, diluting the lubricating oil. In addition, a long time of bad use will also lead to the piston, valve and combustion chamber carbon accumulation significantly increased, resulting in nozzle blockage and plug stuck.
(10) The diesel engine suddenly adds cooling water when the temperature is too high
when the diesel engine is short of water and overheated, cracks will occur in the cylinder head, cylinder liner, cylinder block, etc. due to drastic changes in cold and heat. Therefore, when the temperature of the diesel engine is too high, the load should be removed first, the speed should be increased slightly, and the diesel engine should be turned off after the water temperature drops, and the water radiator cap should be loosened to remove water vapor. If necessary, slowly pour cooling water into the water radiator.
(11)Long-term idle operation of the machine
Diesel engine idle speed, low lubricating oil pressure, piston top oil injection cooling effect is poor, resulting in increased wear and tear of the machine, easy to lead to pull cylinder situation, but also cause poor atomization, combustion is not sufficient, serious machine carbon, and sometimes even lead to valve and piston ring seizure, cylinder liner cavity corrosion. For this reason, some of the diesel engine manuals specify that the diesel engine idling time shall not exceed 15 ~ 20min.