Caterpillar excavator details
Service time: 7300 hours
Maintenance process:
1. First, check the starting circuit, and no fault is found; Then check the low-pressure oil circuit of the fuel system, the fuel pipeline is normal, the fuel tank is sufficient, the vent hole of the fuel tank cap is not blocked, the fuel tank switch is open, and the hand oil pump supplies oil normally
2. After the diesel engine is running, use ET (electronic technician) to conduct cylinder disconnection test. The results show that the injector solenoid valve works normally, but the injector atomizes poorly. It is suspected that the mechanical part of the injector is faulty The fuel injector (see the attached figure for its structure) was disassembled from the diesel engine. It was found that the plungers of the six fuel injectors had been seriously worn, and the fuel injector spool had also been worn to varying degrees.
Cause analysis:
1. From the above fault diagnosis results, it can be seen that the direct reason why the diesel engine can not be started is the serious wear of the injector plunger, and there are generally three specific reasons for the serious wear of the plunger: the first is the quality of the plunger itself, the second is the incorrect installation of the injector, and the third is the diesel quality The analysis shows that the first two possibilities are very small. Through the oil sample inspection of the diesel used in the engine, it is found that its water content exceeds the standard.
2. Drain the diesel fuel with excessive water content, replace the diesel filter element, add qualified diesel fuel, replace 6 new fuel injectors, remove the air from the fuel supply system, and then start the diesel engine. The startup and operation are normal Conduct et test on the diesel engine again, and all parameters are normal.
Key points for excavator maintenance:
1. Selection, storage and transportation of diesel oil
Diesel oil with appropriate brand and qualified quality shall be correctly selected according to different seasons and the temperature in the area where the machine is located; Diesel oil with a solidifying point 3~5 ℃ lower than the local temperature shall be selected to prevent diesel oil from solidifying at the lowest temperature; During the transportation of diesel oil, the container shall be kept closed to prevent dust and impurities from mixing in the diesel oil; The diesel oil shall be properly kept during storage to avoid infiltration of moisture and other impurities.
2. Do a good job of daily maintenance
Regularly check the fastening and sealing of all joints of the diesel oil circuit to avoid air entering the oil supply system; The vent hole on the oil tank cover shall be kept unobstructed to avoid negative pressure of the oil tank; Pay attention to the filtering effect of the diesel filter, regularly replace the filter element and clean the filter screen; Check the differential pressure of the diesel filter frequently to find and eliminate the fault in time; At the end of each day's work, it is best to add enough diesel oil to the oil tank, which is conducive to removing the air in the diesel oil and avoiding the water vapor in the oil tank condensing into water and penetrating into the oil; Drain the water and impurities in the oil-water separator at least once a week.
3. Use original accessories
When replacing parts and components of diesel supply system such as fuel injector, fuel transfer pump, diesel filter and oil-water separator, original accessories shall be selected.
