When diagnosing such failures of refrigerated trucks, it is necessary to proceed from the most obvious point of the fault characteristics. Whether it is continuous or intermittent black smoke, this principle should be followed.
1If the engine of a refrigerated truck suddenly emits black smoke, but the fault disappears naturally after running for a period of time, it is mostly caused by poor fuel quality. Because of the poor quality of the injection caused by impurities in the oil, the exhaust gas emits black smoke. After a certain period of time, the impurities are washed away by the high-pressure oil. This type of failure is not dealt with.
2 If the refrigerated truck is continuously emitting black smoke, it may be considered whether the intake air is unobstructed and whether the intake pipe is deformed, which increases the intake resistance. Remove the air filter cover first, remove the filter element, clean it, and then retest the machine to see if the exhaust pipe continues to emit black smoke. If the smoke is significantly reduced, it indicates that the air filter is dirty or has problems with the installation, which affects the intake air volume and the maintenance of the air intake system should be strengthened.
3 If the inlet air flow of the refrigerated truck is unobstructed, check whether the time for fuel supply is too late and form black smoke.
4 Most of the injectors have severely deteriorated injection quality and have poor fuel atomization. They cannot adapt to the shape of the combustion chamber, resulting in difficulty in the formation of combustible mixtures, and the conversion of some of the fuel into free carbon. This is also one of the causes of black smoke, so the injectors should also be checked and repaired.
5 Check whether the fuel quality of the refrigerated truck is in conformity with the standard, and the standard diesel that meets the engine's normal working temperature in the area should be used.
6 Check whether the refrigerated car turbocharger is working properly. When the supercharger fails, the pressure at the end of the engine intake drops, causing the compression end temperature and pressure to drop, affecting the fuel atomization and combustion temperature.
7 If the maintenance time of the fuel pump is not long, the exhaust pipe is black smoke, and the power is insufficient, consider whether the fuel pump is adjusted excessively to make the fuel supply excessive, and the fuel supply of the fuel pump under various working conditions should be re-calibrated. Quantity, make it meet the regulations.
8 If all of the above are normal and the engine has been running for a long time, consider checking whether the valve opening height and opening time are correct. The use of a long time, can make valve transmission parts wear, the normal valve timing and valve lift misalignment, reduce the amount of intake air, the amount of residual gas in the cylinder increases, a direct impact on the full combustion of fuel.
9 For unequal rotation speed, intermittent black smoke, and engine powerlessness can be checked by cylinder-by-cylinder oil shut-off.
When a cylinder is cut off, the engine speed is significantly reduced, black smoke is reduced, and abnormal noise disappears. This indicates that the cylinder has too much fuel supply, and the cylinder fuel injection volume should be checked and adjusted. If the change of the engine speed is small and black smoke disappears, the quality of the spray of the cylinder injector is poor, and the injector should be checked and maintained. If the engine speed still does not change, then the cylinder does not work, you should check the cylinder's high-pressure fuel supply conditions, such as the injection pump plunger, the oil valve how to match, pull the fork on the oil adjustment lever on the fixed screw ( Or whether the fastening screw of the ring gear is loose or not, and whether the plunger spring is broken or not. If normal, check the injector's working condition and the cylinder for mechanical failure.
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