Common rail
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  • With the plan to launch the national six heavy diesel vehicle in 2021, the engine becomes more and more “fine”, which makes card friends need to strengthen daily maintenance, prolong the service life of the engine and reduce service faults.Xiaobian has sorted out the information about the daily Common rail maintenance of national five and national six engines. If there are deficiencies, please leave a message in the comment area!
Common rail

High pressure common rail of Safet requirements:

  • During the operation of common rail diesel engine, it is strictly prohibited to engage in the disassembly of common rail high-pressure circuit, including oil rail, pressure control valve, pressure limiting valve, rail pressure sensor, relevant harness and Common rail high-pressure oil pipe.
  • Why is it forbidden to operate the common rail oil circuit during operation? This is because the common rail pressure is up to 2500bar, or 250Mpa. In popular language, it will be 25000 meters (in the pipe) of vertical water column, which can easily break the stone. When loosening the high-pressure pipeline when the engine is running, Common rail the oil beam may catch fire when encountering hot engine parts, which is a risk of fire.
  • It is generally required to shut down the engine for five minutes before repairing the engine fuel rail. The pressure of the first disassembled high-pressure component should be relieved slowly according to the guidance documents.
Common rail

High pressure common rail of cleanliness requirements:

  • Clean the high-pressure rail during disassembly and maintenance, that is:
  • (1) Before disassembly, it is necessary to clean the oil rail connection point and its surrounding area to prevent “dirt” during disassembly;
  • (2) After the parts are disassembled,Common rail the parts shall be placed in a clean place and covered with dust. Pay attention not to use the “hair falling” cloth;
  • (3) If the repair and maintenance are not completed immediately, the exposed openings need to be covered;
  • (4) New parts can only be opened from the package during assembly. Do not use parts stored without packaging. For example, put them randomly in the tool box. After the assembly is disassembled, do not move the vehicle as much as possible Common rail.
Common rail

High pressure common rail of common rail routine maintenance requirements:

  • Routine maintenance: replace the three filters (air filter, mechanical filter and diesel filter) and engine oil. The three filters should be replaced in time as required. Considering the quality of diesel and engine oil, the diesel filter element and engine oil filter element should be replaced before the specified mileage or working time. Moreover, the filter element should be of the brand required by the manufacturer and should not be replaced at will.
  • Once the vehicle is found to be abnormal, go to a regular maintenance enterprise with maintenance ability for maintenance Common rail
Common rail
  • Routine maintenance of urea SCR system
  • In the combustion process of engines using urea SCR route, the number of particles is effectively controlled through technical means, such as increasing the combustion temperature in the cylinder, but nitrogen oxides will be produced.
    This requires the reduction of its nitrogen oxides into nitrogen and water in the post-treatment process.
  • The specific working process is not described in detail.
    Generally speaking, urea crystallization can be summarized as the evaporation of water in urea solution, which increases the concentration of urea solution and forms saturated solution to produce urea crystallization.
  • When there is a small amount of crystallization, it will not affect the use. It is directly filtered out by the urea filter element. Therefore, the urea filter element needs to be replaced in daily maintenance. Generally, the filter element is at the outlet pipe of the urea tank.
  •  Daily use requirements of urea SCR system:
    The following are the problems that Common rail need to be paid attention to in the daily use of urea SCR.
  • (1) Urea is alkaline and corrosive to engine materials. If there is overflow during filling, it will pollute the vehicle. Therefore, a special filler pipe should be used during filling;
  • (2) During urea filling, impurities shall be avoided from entering the solution as far as possible to reduce the possibility of blockage of urea solution pipeline and urea pump;
  • (3) When cleaning SCR, use purified water instead of tap water and mineral water;
  • (4) In case of urea crystallization, wash with hot water and try not to use cleaning agents, especially fake and shoddy products;
  • (5) The engine should be idled for a while before stalling, because there is less urea injection when the engine is idling, so there will be no urea accumulation in the pipeline, and there will be no crystal accumulation after water evaporation
Common rail
  • (6) After some engines shut down, SCR will continue to operate and blow out the residual vehicle urea. Therefore, after parking, don’t hurry to turn off the power of the whole vehicle, usually after 30 seconds;
  • (7) As for vehicle urea solution, generally do not change the brand at will, so as not to cause engine alarm;
  • (8) Urea solution should be well preserved in our daily use to avoid high temperature and direct sunlight;
  • (9) Replace the urea filter element regularly, and replace the air filter element for the air driven urea pump. During routine maintenance,Common rail if the maintenance personnel forget, card friends should remind them.
  • daily maintenance of exhaust gas recirculation EGR Common rail
  • Xiaobian sorted out several cases and simple solutions to EGR problems
  • During rapid acceleration, the engine emits black smoke, high fuel consumption and slow acceleration.If there is no regular maintenance, the EGR valve may be stuck in a large open state due to carbon deposition.
  • This will cause excessive exhaust gas in the cylinder, less oxygen, less fresh air, incomplete diesel combustion, large power loss and poor power performance.
  • The electronic control unit stores fault codes related to EGR. This is to check the parts related to EGR, exhaust temperature sensor, EGR vacuum regulator, EGR valve, EGR inlet pipe, etc.
Common rail
  • The signal voltage of intake manifold absolute pressure sensor is high. In case of poor idle speed, shaking and weak acceleration at low speed, it is necessary to detect the vacuum degree of the intake pipe. The air inlet is not unobstructed, and there may be carbon deposition.
    In the inspection of engine EGR, attention should be paid to the antifreeze loss caused by the internal rupture of EGR cooler. If there is a large loss of antifreeze, it may be the problem of EGR cooler.
  • Most of the combustion exhaust gas of the engine is water vapor, which becomes water droplets after cooling. It is precisely because of the phenomenon of water droplets that we should beware of EGR failure caused by icing.
  • In areas where the weather is not cold, there will certainly be no icing, so there is no need to worry about such problems in daily use. If you are in a cold area, you need to pay attention to the icing problem caused by engine shutdown.
  • particulate trap DPF
    DPF in daily use mainly includes three processes: particle filter empty, particle filter full and particle filter reduction.
  • In short, when the DPF is empty, the exhaust resistance is small, the engine power loss is small, and the operation efficiency is high. When the engine works for a certain time, the particles in the particulate filter are full, the exhaust resistance increases and the power decreases. After the particulate trap is full, regeneration is required, which involves active regeneration and passive regeneration. Xiaobian will not describe it in detail.
Common rail
  • Routine maintenance of particulate trap DPF
  • However, the regeneration is only aimed at removing the carbon deposits inside the DPF, and the ash substances that are not carbon deposits cannot be reduced and decomposed at all. So where does the ash come from? Ash is mainly the component of engine oil and fuel. Because ash cannot burn, the effective volume of particulate filter is reduced. After a certain period of use, the function of particulate filter will deteriorate and the loss of engine power will increase.
  • Therefore, for diesel vehicles with DPF, carders should first choose low ash engine oil and regularly clean and regenerate the interior of DPF to ensure the actual capture efficiency of DPF.
    Maintaining the efficient operation of the particulate trap can effectively reduce particulate emissions, prolong the service life of DPF, reduce later maintenance costs, reduce engine power loss and reduce fuel consumption. For regular cleaning of DPF, you can choose some DPF cleaner products – diesel particulate filter cleaner and diesel particulate filter flushing fluid.
  • In actual use, we should not use inferior diesel and engine oil, and do not cause heavy losses in order to save money for a while.
  •  summary
    The problems encountered in daily use are certainly more than what we mentioned above, and various faults emerge one after another. In the face of faults and problems, we should face them calmly, and troubleshooting and analysis one by one is the king.
  • In use, the most important thing is not to solve the problem, but to prevent the occurrence of the problem. This requires the majority of card friends to actively study in life and carry out regular maintenance of the vehicle according to the use and maintenance manual.
  • Compared with maintenance, normal maintenance is actually more economical. It does not delay normal use, nor will the cost rise sharply due to maintenance, and reducing the number of maintenance can improve the durability of the engine.
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