A Caterpillar cat323 excavator owner was very troubled. After working for one day on the construction site, he found that there was no way to start it when preparing for construction work the next morning, and he could not see the appearance in appearance. The Lord contacted the repairman as soon as possible. After 7300 hours of use, the machine appeared to be unstable and sometimes emit black smoke, which caused difficulties in starting or even failing to start. Today, Liteng Machinery shared the case that the excavator cannot start.
Carter excavator details
Use time: 7300 hours
Maintenance process:
1. First check the start circuit, no faults are found; then check the low-pressure fuel circuit of the fuel system, the fuel line is not abnormal, the fuel tank has sufficient oil volume, the vent of the fuel tank cap is not blocked, the fuel tank switch is open, and the hand pump supplies oil normal.
2. After the diesel engine is running, use ET (Electronic Technician) to perform the cylinder break test. The results show that the injector solenoid valve is working properly, but the injector has poor atomization of the fuel injection, and it is suspected that the mechanical part of the injector is defective. The piston was disassembled and disassembled from the diesel engine, and it was found that the plungers of the six injectors had been severely worn, and the spool of the injector nozzle also had different degrees of wear.
Cause Analysis:
1. From the above fault diagnosis results, it can be seen that the direct cause of the diesel engine's inability to start is the severe wear of the plunger of the injector, and there are generally three specific reasons for the severe wear of the plunger: one is the quality of the plunger itself, and the other The fuel injector is not installed correctly, and the third is the quality of the diesel. The analysis shows that the first two possibilities are very small. After an oil sample test of the diesel used in the engine, it was found that its water content exceeded the standard.
2. Discharge the diesel with excess water content cleanly, replace the diesel filter, add qualified diesel, replace 6 new fuel injectors, remove the air from the fuel supply system, and then start the diesel engine, the start and operation are normal. The diesel engine was tested by ET and all parameters were normal.
Main points of excavator maintenance:
1. Do a good job in the selection and storage of diesel oil
According to different seasons and the temperature of the area where the machine is located, the diesel with the appropriate grade and qualified quality should be selected correctly; the diesel with a freezing point 3 to 5 ℃ lower than the local temperature should be selected to prevent the diesel from solidifying at the lowest temperature; in the process of transporting diesel The container should be kept closed to prevent mixing of dust and impurities in the diesel; when storing the diesel, it should be properly stored to avoid the penetration of moisture and other impurities.
2. Do daily maintenance work
Always check the tightening and sealing of the joints of the diesel oil circuit to avoid air from entering the fuel supply system; the vent holes on the fuel tank cover should be kept clear to avoid negative pressure in the fuel tank; pay attention to the filtering effect of the diesel filter, Regularly replace the filter element and clean the filter screen; the pressure difference of the diesel filter should be checked frequently in order to find and eliminate the fault in time; after the end of the work every day, it is best to add enough diesel in the fuel tank, which is beneficial to eliminate the air in the diesel and avoid The water vapor in the oil tank condenses into water and penetrates into the oil; the water and impurities in the oil-water separator are excluded at least once a week.
3. Use original accessories
When replacing parts of diesel supply system such as fuel injector, fuel pump, diesel filter and oil-water separator, original parts should be selected.
