The main causes of black smoke from diesel engine caused by intake system are: too much resistance of air filter or intake pipe. Generally, the resistance of intake pipe is constant, and the resistance of air filter may change at any time.
(1) Air filter problem if the air filter is dirty or the inferior air filter element is used, it may increase the resistance in the near future, reduce the amount of fresh air entering the cylinder, and cause black smoke from the diesel engine. If the diesel engine does not smoke originally, and the smoke increases after replacing the air filter element, it indicates that there is a problem with the quality of the air filter element.
(2) Intake pipe problem if the intake system is blocked or the pipe is too long, it may increase the intake resistance. Too much intake resistance will cause black smoke from the diesel engine. If the intake air temperature is too high, it will also cause black smoke from the diesel engine.
In addition to the black smoke from the diesel engine caused by the failure of the intake system, there are also the following phenomena:
. the diesel power is insufficient. The fuel consumption of the diesel engine increases. The basic method to confirm whether the diesel engine emits black smoke due to the failure of the intake system is as follows:
. resistance of air filter element: start the diesel engine at low speed, remove the air filter element (including paper core and felt core), and then observe the change of exhaust smoke. If the smoke of diesel engine decreases after removing the air filter element, it indicates that there is a problem with the air filter element. If it is confirmed that there is no problem with the quality of air filter element, further check the resistance of intake pipe.
. intake pipe resistance: disassemble the intake pipe interface outside the intake pipe of the diesel engine to make the air directly enter the intake pipe of the diesel engine, then start the diesel engine at low speed and observe the exhaust smoke. If the smoke is reduced, the intake system resistance is too high.
. intake air temperature: if the exhaust pipe is too close to the intake pipe, or there is air leakage at the interface of the exhaust pipe, it may have a direct impact on the intake air temperature. If the diesel engine idles and idles smokeless, black smoke will appear after loading, and the greater the load, the more serious the black smoke. After excluding other factors, the influence of intake air temperature should be considered. Under normal conditions, the inlet air temperature shall not be higher than 45 ℃.
Troubleshooting: replace the new and high-quality air filter element, dredge the air inlet pipe and eliminate the heating of the air inlet pipe.
Special note: the diesel engine cannot run for a long time without air filter element, especially when the field environmental conditions are bad.
