At present, some of the main models of bulldozers on the market are equipped with National III diesel engines. The structure and principle of the fuel supply system are quite different from those of National II diesel engines. The maintenance methods are also different. Now I will list the low efficiency of this type of engine. Some troubleshooting methods for insufficient diesel engine power and black smoke in the exhaust.

First, check whether the diesel engine water temperature, engine oil temperature, intake air temperature and pressure (including sensor failure) are normal. After the metering unit, rail pressure sensor, fuel line, and second injector fail, the diesel electronic control unit detects the failure. It will stop immediately, but limit the power of the diesel engine, so that the speed of the diesel engine can only be increased to 1 500r/min, and the power will be insufficient when using the bulldozer. When there is insufficient power, first check whether the instrument has a fault code display, and then find the fault location according to the fault code to eliminate the fault.

If the instrument has no fault code display, it is mostly because the mechanical part is faulty. According to a user of a bulldozer, the fuel and oil filter elements have been replaced in accordance with the diesel engine maintenance regulations for 250 hours, and the air filter has been cleaned regularly. After the second 250h maintenance, there was insufficient power and no fault code. This ruled out the electrical control system failure and judged it as a mechanical failure. The inspection found that there was oil contamination at the connection between the exhaust manifold of the third cylinder of the diesel engine and the cylinder head. Disassemble the exhaust manifold and find that there is oil in the exhaust duct. Remove the injector and send it to a professional maintenance station for testing on special equipment. After testing, it is found that the injector needle valve is stuck and cannot work.

Therefore, the analysis shows that the oil in the exhaust duct is caused by the inoperability of the injector of the cylinder, which causes the volatile oil to condense and leak here. After installation and maintenance of the injector, start the diesel engine, the diesel engine starts normally, the smoke color is normal, there is no black smoke when working under heavy load, the performance of the whole machine is restored, and the power shortage fault is eliminated.