Diesel engine is a kind of precision machinery, and its function must be guaranteed for a long time, which is inseparable from normal maintenance. The early failure of the diesel engine is generally caused by the following reasons:
◆Illegal operation, poor management and use;
◆Do not carry out maintenance and maintenance according to the regulations or even use repairs instead of maintenance;
◆The parts are poorly manufactured, especially if you buy fake and shoddy products for cheap, it will greatly shorten the life of the diesel engine;
◆The grades of fuel and lubricating oil are improperly selected or unqualified.
Commonly used diagnostic methods for diesel engine failures generally include:
◆Observation method: judge the fault condition by observing the fault characteristics such as the exhaust smoke of the diesel engine.
◆Auscultation method: According to the abnormal sound of the diesel engine, the nature and degree of the fault location can be judged by hearing.
◆Cylinder cut-off method: Stop the work of a certain cylinder to judge whether the fault occurs in this cylinder. The cylinder cut-off method is generally to stop the oil supply to the cylinder suspected to be faulty, compare the state changes of the engine before and after the cylinder is cut off, and narrow the scope for further finding the fault location or cause.
◆Comparative method: For certain assemblies or components, use the replacement method to determine whether there is a fault.
Engine won't start
◆Check whether it is hung in the neutral position
Before starting the car, first check whether the gear lever is hung in the neutral position.
◆Check whether the battery voltage is too low to drive the starter
Generally, the battery voltage is 24V. If it is too low, the starter cannot be driven. You can check it with the voltage range of a multimeter or read the actual value "battery voltage" with a fault diagnosis instrument.
◆Whether the starter relay and wiring are in good condition
Check whether there are too many oxides on the surface of the terminal, and whether the bolts on the surface of the terminal are loose or broken.
◆Check whether the starter is burnt out
Use a multimeter to check if the starter relay is normal.
◆Is the ignition switch and starter switch damaged?
Turn the ignition key to the ON position and check if the dashboard light is on
Turn the ignition key to the starting gear, and check whether the starter works (this is on the premise that other reasons are excluded).
Starter works but won't start
◆Check whether the oil level in the fuel tank is too low
This reason is relatively easy to ignore and needs attention.
◆Check whether the hand oil pump is working normally
Press the manual oil pump with your hand to see if it is normal.
◆Check whether there is air in the low-pressure oil circuit, and discharge the air (sometimes the leakage of the low-pressure oil circuit is not obvious, and it needs to be checked carefully)
Exhaust method: mainly exhaust the air inside the coarse filter. Loosen the bleed bolt on the coarse filter, and press the hand pump on the coarse filter by hand until the oil continues to flow out from the bleed bolt.
◆If the diesel engine still cannot be started after the air in the low-pressure oil circuit is exhausted, it is judged that there is air in the high-pressure oil circuit, and the air in the high-pressure oil circuit needs to be discharged
Exhaust method: Loosen the high-pressure oil pipe of a certain cylinder, and use the starter to drive the diesel engine to run until the high-pressure oil pipe continues to discharge oil! (It is not recommended to disassemble the high-pressure oil pipe joint frequently!
◆Check whether there is leakage in the high-pressure oil circuit
This situation is generally more obvious. Check whether the nut of the high-pressure oil pipe joint is loose, and if so, tighten it.
◆Check whether the oil circuit is unobstructed, check whether the diesel filter is clogged, and it is recommended to replace the diesel filter element in time.
Inspection method: Loosen the outlet bolt of the fine filter, use the starter to drive the diesel engine to run, and see if there is diesel injection or outflow, if only a small amount of diesel oil flows out, it can be judged that the filter element is blocked, and the filter element needs to be replaced at this time.
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