Many machine friends have experienced such a thing. During the construction of the excavator, an abnormal noise can be clearly heard from the engine part, the sound is very sharp and continuous. Many machine friends will be frightened by this abnormal sound at a loss, but in order to catch up with the construction period, they want to wait until the end of the project to deal with them in a unified way. This is absolutely unworkable, beware of small problems that lead to big problems!
Diesel engines make a lot of noises when they are working, including normal noises (natural noises) and abnormal noises (abnormal noises). During normal operation, the sound is rhythmic, uniform exhaust sound and slight noise, which has a certain regularity. When the diesel engine parts have abnormal percussion or firing sound during use, this is an abnormal noise. So, how to judge the common abnormal noise? How to deal with it? Let's take a look at the phenomenon and causes of abnormal engine noise.
Engine abnormal noise can be classified into three types: sudden abnormal noise, natural increasing abnormal noise, and man-made abnormal noise:
1. Sudden abnormal sound (the engine had no such sound)
Inspection Method:
1. The sound position is on the cylinder head, and the cold and hot engines exist at the same time. The cylinder break method should be used to check when the engine is idling. When the engine is idling, cut off the oil at the high-pressure oil pipe joints of each cylinder one by one, and loosen the cylinder. If the abnormal noise disappears, the fuel injector of the cylinder is stuck.
2. The engine has a heavy impact sound. If the cylinder pulls the cylinder, the engine power is obviously reduced. The engine is particularly strenuous at idling speed, and even the exhaust pipe appears black smoke. Broken piston ring, poor combustion, poor piston cooling, abnormal operation of the oil nozzle, and high engine temperature are the main reasons for the abnormal noise.
3. If there is a dry grinding sound of the compressor shaft, the main reason is that the compressor oil pipe is blocked or the oil pipe is broken and the oil leaks. At this time, the compressor appears to be very hot and abnormal noise occurs, and it should be shut down in time for inspection and treatment.
4. If the impact sound occurs when the turbocharger rotates, the abnormal noise of the turbocharger is mainly caused by the axial or radial movement of the turbocharger, which causes the blades to collide with the shell. The impact is not serious, it is easy to hear when changing speed, and it is not easy to hear when the speed is steady because of the small vibration.
2. Naturally increasing abnormal sound (the sound from nothing to small, then gradually expands)
Inspection Method:
1. The air valve sealing belt is not tightly sealed due to ablation and carbon deposits, and the sound is located at the cylinder head.
the reason:
(1) The valve clearance is too small and blow-by after the engine is warmed up.
(2) Valve deposits or burns (organic oil in the cylinder, poor atomization of the fuel injector, incomplete combustion, high engine temperature).
2. The main bearing bush or connecting rod bush is worn, the impact of the crankshaft is very loud, the sound is at the oil pan, and the sound is clearer 10 meters away from the engine. For example, when the connecting rod bearing is worn seriously, the sound of the piston pumping the valve will appear at the same time (the valve vibration is very large at this time). The bearing bush is worn and the oil pressure is reduced. When the oil is drained, there must be bearing bush alloy fragments on the oil plug.
Note: Bearing bush burns are very dangerous. Once abnormal sound is found, the machine must be shut down for inspection and treatment.
3. The piston pin and the pin hole are worn too much, the piston and the cylinder liner pull the cylinder, and there will be a heavy impact at the same time.
4. The idler gear shaft is worn, the meshing gap of the timing gear is too large, and there is a very rusty impact sound at the gear chamber. When the speed changes, the impact sound is more obvious.
5. The noise at the clutch, when the release bearing is damaged, the driven disc steel sheet or the rivet is loose and damaged, the impact sound will be generated. The higher the speed, the louder the noise, and the noise will become smaller or even no when stepping on the clutch, and the noise will be at the flywheel shell. .
3. Man-made abnormal noise (sound caused by improper installation or improper adjustment).
1. Abnormal noise caused by excessive valve clearance, which is located on the cylinder head, is generally obvious in low-speed cooling, but not obvious in high-speed warming. If the valve clearance is too small, there will be air noise, which is more obvious when the engine is warming up. Just check the valve clearance.
2. The vibration of the engine (sometimes even with the vibration of the whole vehicle) occurs when the engine is rotating in a particular belt. This is the resonance sound caused by the defective chassis structure and engine installation. This situation requires detailed inspection to determine.
3. The chaotic airflow impact sound in the exhaust pipe is mainly due to the change of the engine's air distribution phase. The reasons for this failure are:
(1) The push rod is bent or broken, and the valve spring is broken.
(2) The crankshaft timing gear or pulley, which is connected and positioned without a locating pin or key, is displaced, resulting in abnormal air valve phase. Check the gas distribution phase and adjust it.
Conclusion: We can know that the abnormal noise of the engine is mostly caused by the excessive wear of the parts and the increase of the matching clearance. Therefore, the use of suitable brands of lubricating oil and regular replacement, maintaining good operating habits can effectively slow down the wear of the parts. If the parts are worn or loose, repair the excavator in time. For faults such as large valve clearance and improper fuel supply, relevant parts should be adjusted in time to avoid damage to important parts and cause major losses.
