The faults in the oil circuit are complicated to check. The low-pressure oil circuit of the diesel engine does not come from oil or the oil is low. There are many factors involved, and it is easy to find a detour and find time.
Is there a quick and easy way to check the oil circuit failure? This is about our protagonist today: the hand pump.
The basic purpose of the hand pump is to have air in the oil passage of the diesel engine, such as a new car that has just been off the line, or the oil in the fuel tank has burned out. When the engine is started, the engine cannot be started because the diesel fuel pump can only work when the engine is started. . At this time, it is necessary to pump the fuel in the fuel tank into the oil passage by means of a hand pump.
Today, I will share a few tips with you, just by using the engine's own hand pump to compare the different feelings and changes of the oil when it comes to normal, and find out the cause of the fault faster.
First, a brief understanding of the working principle of the hand pump: When the piston moves upward, the volume in the pump chamber expands to form a vacuum, so the check valve 2 is closed under the action of the spring. Under the action of atmospheric pressure, the check valve 1 is opened, and the fuel is fed through. The tubing enters the pump chamber.
When the piston moves downward, the oil pressure in the pump chamber rises, the check valve 1 is closed, and the check valve 2 is opened, the fuel is discharged from the oil outlet, and the continuous pumping of the driving pump is repeated.
Oil circuit has suction
Loosen the oil circuit to deflate the nails, pump the oil with the oil pump, and gently pull the handle upwards. If you feel the suction of the oil passage slightly, the fuel is discharged at the venting nail when the handle is pressed, indicating that the oil absorption resistance of the oil pump is too large.
The reason for the decrease in oil is that the vent hole on the fuel tank cap is clogged, and a negative pressure is generated in the fuel tank, which affects the oil: the viscosity of the diesel used in winter is too large, and the fluidity is poor.
Draining oil with mixed gas
When pumping oil, the fuel overflowing from the venting nail is mixed with gas. If the handle is felt to have resistance and the amount of fuel discharged is small, the filter or oil path between the oil pump and the high pressure oil pump is blocked. cut back.
The vehicle can't catch fire, and the oil pump can start with the oil pump.
The vehicle has not been able to catch fire. The oil can be ignited by using the hand oil pump, but the engine will immediately turn off after stopping. Generally, due to the pressure relief point at the oil circuit system, the pressure is insufficient, the fuel cannot be delivered to the engine, and the pressure on the oil circuit is checked.
The output fuel is mixed with gas
When pumping oil, the fuel output from the oil drain screw is mixed with gas; the oil pipe joint from the oil drain screw to the oil pump is not tightened; the joint seal is damaged or the oil path is broken, causing air leakage, from the threaded connection on the oil pump Or the gas is sucked into the gap between the piston of the hand pump and the outer wall; the nozzle nozzle is stuck in the open position, the oil outlet valve is poorly sealed, and the high pressure gas in the fuel chamber is plunged into the low pressure oil passage (the gas can be quickly discharged by the hand oil pump, However, after starting, gas will be intruded; the oil level of the fuel tank is too low to attract air; the oil passage from the fuel tank to the oil pump is severely blocked, and it is easy to inhale the gas.
Small resistance at the handle
If you do not loosen the air nails, if you press the handle for a long time and always feel less resistance, the oil return valve on the high pressure oil line or the oil inlet and outlet valves in the oil pump will be poorly sealed and the oil will leak.
The reasons are: the valve surface is seriously worn; the valve surface is contaminated with impurities; the valve spring is damaged.
When we check, we can check out the general fault point of the engine through some auxiliary devices of the engine itself. As long as the scope is determined, the specific reason is easy to deal with, so we should be good at using effective methods to find more quickly. And solve the engine failure.