Carefulness is the premise of doing everything well, which is particularly important for our maintenance masters; Many times the car can’t be repaired well. It’s not that we are incompetent or lack of knowledge, but that we are not careful enough. This issue of small rail brings you a wonderful failure case.
The Sany cement pump truck uses Dongfeng’s chassis (Cummins Engine), and the top engine is heavy truck man series engine mc07. When the vehicle is running, Cummins engine is used, while heavy truck mc07 engine does not work; When transporting concrete, the mc07 engine of SINOTRUK man works. This fault occurred on the mc07 engine of heavy truck man .
After arriving at the fault site, it was found that the cup of the hand oil pump was broken. Since the hand oil pump was installed on the low-pressure oil circuit, it was ruled out that the shell of the hand oil pump was cracked due to high oil pressure.
Check whether there is interference between the hand oil pump cup and the engine, and no interference is found.
There is no interference in the static state. It is suspected that it is caused by excessive vibration of the engine itself. Check the cause of the engine itself.
2. Read fault code
Replace the cup with a new one to make the fuel system work normally. Then the decoder reads the fault and shows that the system is normal.
3. Use a diagnostic expert to read the data stream repaired
The car has been repaired for two months, but no one thought of the point of failure
No abnormality is found in the engine data stream; However, it is found that the engine vibrates too much at idle speed, so the idle speed will be raised in the next step.
4. Idle the engine to 800rpm
After calibration, there is no obvious jitter at idle speed.
5. Two weeks later