It is inevitable that a diesel engine will malfunction during long-term work. The usual solutions are to check, ask, listen, and watch. The most effective and direct method is to judge and solve the problem through sound, and can use the sound to judge and solve the problem. Some prescient small faults are nipped in the bud, avoiding the occurrence of major faults. This is also a major advantage of using listening to troubleshoot problems instead of finding faults by looking, looking, and asking questions. Today, we will continue the previous article to talk about how to diagnose faults by listening to the sound of the excavator diesel engine.
5. When the diesel engine suddenly changes the load, a dull knocking sound can be heard near the engine body. This is mainly caused by the abnormal friction between the crankshaft connecting rod journal and the connecting rod bush. The main reason is that The gap between the connecting rod journal and the connecting rod bush is too large, causing local jump. The mechanism and maintenance detection method of producing this sound are exactly the same as those of the main shaft and main bearing bush.
6. At the front cover of the diesel engine, you can clearly hear a “howling” sound. This sound comes from the meshing gears inside the front cover. The gears of each meshing gear are excessively worn, causing the gear clearance to be too large, causing the engine to malfunction. The gears cannot enter the normal meshing state to produce this kind of sound. The solution is to open the front cover, check the gear meshing with lead sheets or paint, and make adjustments. If the gear gap is too large, new gears must be replaced in time.
7. The sound of objects colliding can be heard in the upper part of the cylinder. While the valve clearance is reduced, the impact sound also increases. The main reason for this sound is the collision between the valve and the piston, causing The main reason for this phenomenon is that the valve clearance is inappropriate, which causes the valve and the piston to collide with each other at high speed when the piston reaches top dead center. At this time, the diesel engine is unable to work and the load resistance of the machine is significantly reduced. The specific method to eliminate this fault is to raise the piston of each cylinder to the top dead center in order, press the valve downward, check whether there is any gap between the piston and the valve, and readjust the valve.
8. A mute and strong knocking sound can be heard along the entire length of the cylinder. This sound is more pronounced when the diesel engine is running at low speed or when the speed changes suddenly. The main cause of this phenomenon is excessive wear of the piston and the cylinder, which causes the piston and cylinder to deteriorate. If the gap is too large, when the piston moves up or down, the piston will move sideways inside the cylinder and swing. When it comes into contact with the cylinder wall, the wear will be aggravated and a dull friction sound will be emitted. After this phenomenon occurs, professional technicians should be found to identify the cylinder liner and piston, and replace the piston or cylinder liner with a new one if necessary.
9. There is a sound similar to tapping an anvil with a small hammer all along the upper and lower parts of the cylinder. The main reason for this sound is that the gap between the piston ring and the ring groove is too large, causing the piston ring to collide with the piston when running up and down. The sound produced when struck is similar to tapping an anvil with a hammer. When this happens, stop the engine immediately and replace the piston rings with new ones.
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Post time: Feb-29-2024