Diesel engine failure occurs frequently in the use of construction machinery, which is mainly caused by improper application and maintenance of diesel engine. Because some machine technical level is not high or thought is not enough attention, in the use and maintenance of construction machinery using some improper operation and maintenance methods, not only affect the engine power and economy, but also become some fault induction factors, directly affect the engine parts and even the service life of the whole machine, so in the use of diesel engine must do the following 4 “do not”.
1. Don’t fill too much oil
You should not want more than less filling oil. Too little engine oil will be sucked out, the oil pressure will drop, the oil can not reach the lubricating surface, will accelerate the wear of parts, and even the occurrence of burning tile accidents. Some users are afraid of lack of oil burning tile, think that more oil is better than less, so often do not follow the regulations of fuel, so that the oil exceeds the standard, in order to “once and for all”. In fact, too much oil has many hazards: (1) easy to leak in the front and back end of the crankshaft, increase the consumption of oil, pollution of the environment, increase the difficulty of maintenance. (2) When the engine works, due to the agitation of the crankshaft, the oil foam deteriorates and increases the rotation resistance of the crankshaft. In addition, the high oil level will also hinder the movement of the connecting rod, thus reducing the mechanical efficiency. (3) Oil consumption increases due to increased combustion caused by oil channeling into the combustion chamber. After oil combustion, it is easy to form carbon deposit in the piston ring, the valve seat on the top of the piston and the oil nozzle, leading to the bite of the piston ring, the oil nozzle plugging and other failures. (4) Too high oil level is easy to produce oil and gas under the agitation of the connecting rod big head, which will ignite in high temperature and cause the explosion of the crankcase. Therefore, the engine oil should be more than less wrong, the general oil level should be slightly lower than the scale on the dipstick is appropriate, the oil level is too high will backfire.
2. Diesel engine speed should not be too slow
Many machines do not want the diesel engine to work under the rated speed, that the speed is low will not fail, in fact, too low speed will bring some adverse consequences: (1) too low speed will reduce the output power of the diesel engine, reduce its dynamic performance; At the same time, the speed of the linkage is also reduced, which will affect the performance of the working machinery, such as reducing the water output of the pump and reducing the head of the pump. (2) Due to the low speed, the injection pressure is reduced, resulting in poor diesel atomization, incomplete combustion of mixture and the formation of carbon deposit. Carbon accumulation is easy to plug the injector hole, cause the diesel engine power drop, exhaust pipe black smoke. Excessive carbon accumulation can sometimes block exhaust pipe mufflers, turbochargers and other parts, so that the diesel engine can not work normally. (3) When the diesel engine is running for a long time at a low speed, the oil pressure is reduced, the oil circulation speed is slowed down, the cleaning capacity is reduced, the sealing and cooling effect is deteriorated, the amount of lubricating oil accepted by the splashing lubrication parts is reduced, so that the surface wear of the moving parts is aggravated, and the service life is reduced. Such as piston, piston ring and cylinder wall wear increases, the transmission parts of the valve mechanism wear intensifies, spindle and connecting rod bearing life reduction. (4) The reserve power of the diesel engine is reduced, so that the diesel engine that should be working normally is in full load or overload working state.
3. Cooling water temperature should not be too low
The water temperature requirements of diesel engines are clearly stipulated, but some operators like to adjust the water temperature very low, some close to the lower limit of the water temperature, or even lower than the lower limit. It is believed that the water temperature is low, there will be no cavitation phenomenon in the pump, cooling water (liquid) will not be interrupted, the use of insurance coefficient will increase. In fact, as long as the water temperature does not exceed 95℃, cavitation will not occur, cooling water (liquid) will not interrupt. On the contrary, if the water temperature is too low, it is very harmful to the work of the diesel engine: (1) the temperature in the diesel engine combustion chamber is too low, the diesel is not easy to atomize combustion after injection, some diesel is still a droplet with the exhaust gas discharge, the smoke color is white. (2) Incomplete fuel combustion and the formation of gum, so that the piston ring stuck in the piston ring groove, stuck valve, compression at the end of the cylinder pressure reduction. (3) After combustion, a part of the product will combine with condensed water in the cylinder and generate acidic substances, which will corrode the cylinder and significantly increase engine wear. (4) The water temperature is too low to reduce the oil temperature, the oil thickens, the flow becomes worse, the oil pump is reduced, so that the oil supply is insufficient, plus the crankshaft bearing clearance becomes smaller, poor lubrication. The test results show that if the coolant temperature drops from 85℃ to 30℃, the engine power decreases by about 8%, the oil consumption increases by 30%-40%, and the wear increases by about 6 times. Therefore, avoid making the water temperature too low when using.
The above problem is the use of maintenance of diesel engine often mistakes, should cause enough attention to the user, in the construction machinery operation to correctly use the diesel engine, give full play to its power and economy, place accidents, extend the service life of the diesel engine and its parts.
4. The oil supply advance Angle should not be too large
Some operators often like to play a little when adjusting the diesel engine oil supply advance Angle, and some even exceed the specified value of 2°-3°. It is thought that if the oil supply advance Angle is adjusted more, the engine will work more vigorously. But the oil supply advance Angle is too large and too small is also harmful: first, the high explosion pressure makes high temperature gas easy to jump into the crankcase, resulting in high temperature oil fission, oil is also easy to evaporate into oil and gas, resulting in crankcase fire; Second, the rapid combustion of excessive fuel in the cylinder will increase the heat load of the piston top, causing overheating damage of the piston; Third, the cylinder liner vibration intensifies, accelerates the generation of cavitation of cylinder liner and body, leading to damage; Fourth, it will cause cylinder knocking, increase the impact force of the piston on the cylinder liner, aggravate the vibration of the cylinder liner, resulting in fatigue damage of the cylinder liner; Five is too large oil supply advance Angle causes excessive fuel accumulation in the cylinder before the top dead center, the explosion pressure after combustion increases, will increase the mechanical load of the piston connecting rod, cause the damage of these parts; Sixth, too high heat load will lead to cracks in cylinder cover, valve seat ring deformation and fall off.
Post time: Feb-15-2023