How can I analyze diesel oils in diesel generators and oil mixed?

Our company's technical department summarizes: there are three common faults for fuel and oil mixing:
(1) The oil pump membrane is rot or delay, so that the diesel flows into the oil bottom shell and the oil mix. Remove the oil pump, plus 3 kg / square centimeter pressure on the oil pump test bench, if the diesel leakage is not found, the oil pump is intact.
(2) The injector fuel injection is low, poor atomization, and the diesel flows into the oil bottom shell along the cylinder wall. The injector was removed and trial on the high pressure oil pump test stage. If the injector fuel injection turning the pressure meets the requirements, the atomization is good, indicating that the injector is intact, otherwise, it is necessary to repair or replace.
(3) the front end of the fuel injection pump, that is, the front end oil seal of the injection pump is inherent, and the gear chamber cover is removed. If there is a large amount of diesel from the back of the fuel pump drive gear, it can determine the diesel in the oil base. Shell is mixed with oil. Removing the injection pump on the high-pressure oil pump test bench test found; many oil seals in front of the front end gear axis neck, a large number of drain, oil seals (material for aluminum alloy), use special tool screws to top traces (Indentation) makes the oil seal seat and the oil seal, causing drain butter oil, ZUI replacing the injection pump, and the fault is cured. This fault description, the M8 screw used when disassembling the fuel injection pump is not too long, and as far as possible, the oil seal seat of the front end of the high pressure oil pump will damage the high pressure oil pump.