Core hints: failure analysis of diesel engines that can not start and work powerless: the removal of engineering machinery faults generally adopts the structure based push method, which is poor in operation. According to the experience of using and repairing engineering machinery for many years, I use the backward push method, that is, from the failure phenomenon, the maneuverability of the troubleshooting is improved, and the fault can be quickly eliminated.
Generally speaking, the construction machinery based on the structure is based on the forward pushing method, and the operability is poor. According to the experience of using and repairing engineering machinery for many years, I use the backward push method, that is, from the failure phenomenon, the maneuverability of the troubleshooting is improved, and the fault can be quickly eliminated.
The structure of the engine on the 1. engine can not be started is basically similar. At present, the conventional diesel engine, represented by the high-pressure oil pump, and the Cummins Engine represented by the PT pump are commonly used. When the battery is sufficient, there is fuel in the tank and the tank switch is open, and the size of the components is correct after repair, the reason that the engine can not start can be judged when the exhaust pipe is incipient.
(1) if there is black smoke discharged from the exhaust pipe, if the black smoke is discharged, it shows that the fuel system works well and the ignition time is accurate; at this time, you can use the manual pump continuous pump oil (the traditional diesel engine) and eliminate the air in the high pressure oil pump at the same time, that is, it can start. If there is smoke but can not start, check whether the engine and the transmission part are separated first, that is, whether the clutch device is open. Such as an Ingrid P600 air compressor to smoke but can not start, check its oil road, circuit and so on are normal, that is, the engine and air compressor separation device is not separated, the starting load is too large, can not start; the separation of the clutch, the engine is very smooth. Secondly, we should check the timing of ignition timing. Because of the correction of the high pressure oil pump, sometimes the error of the marking is often wrong, and the timing of ignition is wrong, which leads to the inability to start. If a CA30 rollers can not be started after the pump is installed (its engine is F6L912), the reason is that the meshing gear in the timing gear room is wrong with a tooth; after correct assembly, the starting is restored to normal.
(2) there is no exhaust gas in the exhaust pipe. If the exhaust pipe has no smoke, it indicates that a system is not working properly. At this time, you can first open the pump oil of the manual pump, observe whether the oil inlet of the high pressure oil pump has the oil flow out, whether the flow is smooth, and open the oil pump outlet of the high pressure oil pump, and observe the oil supply in each cylinder, if the oil flow is normal, and the high pressure oil pump out of the oil outlet is very few, it can be judged to be the high pressure oil pump plunger wear and wear out of limit. If the oil is removed from the oil outlet of the high pressure oil pump when the pump oil is replaced by the pump, it shows that the oil valve is not tight, and the internal leakage is serious. It is necessary to replace or grind, and the diesel engine may start normally. If the fuel system is checked, other systems should be considered. Such as a do8 - 18 bulldozer, the power of the machine is the Cummins NT855 engine. The failure was that the engine was gradually extinguished in normal work and would not start and smoke when starting again. The results of the oil circuit test and the pump test are normal, and the fuel flow rate is also quite good, which indicates that the fuel system is no problem. After opening the valve cover, it is found that the valve clearance which has just been adjusted has become very large again, which indicates that there is a problem in the valve train. When the valve rocker is removed, it is found that both the intake and exhaust valves are bent at the top, indicating that there is something wrong with the timing gear room. The timing gear chamber is removed and the semicircle key of the fixed crankshaft drive gear is smoothed. The driving gear moves outward 10mm to make the whole timing system move. The fuel system, intake system and exhaust system are all in disorder, which is the fundamental reason why the engine can not start.
2., the lack of working ability of the construction machinery is unable to work after starting, mostly due to fuel system problems. The obvious feature of this type of fault is that the engine is running normally at no load, and after being loaded, it shows weakness of work and engine stalling. Examples of such failures are as follows:
(1) a Russian made AI70 bulldozer often feels that the machine is not strong enough to push earth and the engine needs to be turned off. Inspection method: first, the oil of the manual pump is opened, and the oil pipe is found to be out of the oil and the oil circuit is normal, so that the machine can continue to work, but it will not work in a short time. According to this phenomenon, it is presumed that the mechanical pump has failed. When the mechanical pump was dismantled, the four springs were broken into several sections, and only a small part worked. After installing a return spring, the trouble can be eliminated.
(2) a TI 20 bulldozer can operate normally without load, but when it has load, it can only push the earth with 1 gears, and if the D block is working, it should be turned off. Inspection method: first, the fuel manual pump is opened, the system has no air in the system, and the work is normal; after the replacement of the crude oil and thin oil filter, the engine work is basically normal when the small load is pushed to the earth, but it is still not normal under the condition of large load. In this regard, some people think that the high pressure oil pump fuel supply is insufficient, after analysis is considered to be an oil circuit fault. As a result, the oil pipe between the oil filter and the mechanical pump was taken down to check, and it was found that the rubber skin in the tube was aging. It was proved that the oil supply was not smooth and the oil supply was insufficient, which resulted in the powerlessness of the bulldozer. After the oil pipe is replaced, the work is restored to normal.
(3) a Hitachi UHI71 excavator works normally when it is empty, but when it starts digging, it starts to smoke black and is unable to work. Inspection method: first of all, the oil supply system is examined in an all-round way, and the result is normal. It shows that the engine itself has no problems. After observation, it is found that the exhaust pipe has a lot of carbon accumulation, so it is considered that the exhaust resistance is too large, resulting in the decline of power and the smoke of the black. After opening the muffler and removing carbon deposition, the work returned to normal.
(4) a Steyr 1491 dump truck works normally when it is empty. Inspection method: when using the manual pump to pump oil, it is found that there is air in the fuel and other parts work normally. During the inspection, the oil pipe is directly received from the oil tank to the mechanical pump (that is, the fuel does not pass through the oil filter) and then starts the car test. As a result, the car works normally, indicating that the gas leakage occurs in the fuel line; then the transparent plastic pipe of the corresponding diameter is connected to the oil tank to the crude oil filter (replaced by the used joint of the pipe joint. ) no bubbles were found, but a transparent plastic tube was used to connect the crude oil filter to the fine filter. When the pump was pumped by hand, the continuous bubble appeared. It was inspected that the joint had no problem, but the fine filter oil itself had the air leak. After replacing the fine filter, the work is restored to normal.
