During the voyage of the ship, due to the influence of various factors, the diesel engine will produce some noises that can be discerned by human auditory senses.
Among them, some sounds belong to the normal range, and some belong to the abnormal range, which is a manifestation of the fault. The sound that belongs to the abnormal range is called abnormal sound or abnormal sound.
The abnormal noise of the diesel engine is often caused by complicated problems and various phenomena.
Different faults, the reflected sound will be different but sometimes similar. And the same fault, in different models, the reflection is not the same.
Sometimes the normal sound and the special abnormal sound are mixed together, and it is difficult to distinguish it for a while, but after in-depth analysis and looking at the essence through the phenomenon, you can find its regularity.
The reason for the abnormal sound
There are many reasons for the abnormal noise, such as improper installation and adjustment of the diesel engine, untimely maintenance and repair, poor repair quality, improper use and operation, increased fitting clearance due to wear of parts or sudden damage to parts, etc. These factors are affected and changed by the difference of the working temperature of the diesel engine, the lightness of the load, the speed of the speed, the quality of the lubrication, etc., and the severity of the noise is different.
1.The reason why the abnormal sound gradually increases
The gradually increasing sound refers to the sound that is gradually generated and gradually increased unconsciously.
This kind of noise is mostly caused by the gradual increase in the amount of wear on the surface of the relatively moving parts after the diesel engine has been working for a long time, causing the matching relationship to gradually become unbalanced, causing the parts to collide with each other. For example, piston and cylinder wall journals and bearing bushes, piston pins and connecting rod bushings and piston pin holes, valves and rocker arms, and valves and valve guides, etc.
The sound caused by the increase of the wear gap is a gradually increasing sound. The processing of the gradually increasing sound can be treated separately according to the severity of the sound.
If the noise is light and there is no obvious change, it can continue to be used. When the high-grade maintenance or planned maintenance of the diesel engine is carried out, check again.If the noise is louder and becomes heavier rapidly, which will cause the deterioration of the working condition of the diesel engine or damage to the parts, it needs to be repaired in time.
2.Reasons for the sudden appearance of abnormal noisesThe sudden abnormal sound is often caused by the sudden damage of a certain part or the sudden loosening of individual fasteners, resulting in a sudden change in the matching relationship between some parts and parts. Common factors include the following:
1) Loose and fall off of various fastening connectors. For example, the frame fixing bolts of the diesel engine foot are loosened; the fixing bolts of the flywheel and crankshaft balance block are loosened, and the piston pin circlips fall off.
2) The alloy of the connecting rod bearing bush and the crankshaft bearing bush is ablated or peeled off, so that the gap between the bearing bushes increases sharply and generates noise. If this kind of noise is found, if it is not dealt with in time, the crankshaft journal will be rapidly worn, and even accidental damage to the crankshaft will be caused.
3) The connecting rod bolt is elongated or the connecting rod nut is loose, so that the gap between the connecting rod journal and the bearing bush suddenly increases, resulting in a serious knocking sound. If it can be found in time, it can be saved by stopping the vehicle immediately for maintenance, otherwise it may cause a serious accident of pounding the cylinder.
4) The valve spring is broken, which makes the valve spring lose its working ability, and the valve cannot be closed. When the piston goes up, it hits the valve and makes a percussion sound of "Bah, Bah". If it is detected in time, it is easier to eliminate; if it is not detected in time, the diesel engine will continue to work. , The valve lock piece (or lock pin) may fall off, causing the valve to fall into the cylinder, causing accidental damage to the valve, piston, cylinder head and other parts.
5) The pressure adjustment spring of the injector is broken, or the needle valve is stuck in the open position, and the diesel fuel injected into the cylinder cannot be atomized, resulting in uneven operation of the diesel engine, which not only affects the normal operation of the diesel engine, but also has no atomization. After the diesel enters the cylinder, it "leaks" into the crankcase, making the lubricating oil thinner and the lubricating performance worse.Accelerate the wear of the surface of the relatively moving parts, and even cause serious consequences of bearing ablation.
In short, after a sudden abnormal sound is discovered, measures should be taken promptly and decisively according to the severity and location of the sound, and must not be ignored and cause accidental damage.
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