What are the forms of abnormal sound in diesel cylinders?

The abnormal sound in the engine cylinder can be summed into a piston knocking, a piston pin sound, a piston top impact cylinder #, the piston top impact, the piston ring knocking, the valve knocking sound and cylinder knocks and other kinds .
1, piston top and cylinder head
The abnormal sound of the piston top impact cylinder head is \"嗒 \" continuous metal knocking sound, especially when the high speed is very obvious. Its abnormal sound is on the top of the cylinder, and its sound is solid, and the cylinder head is vibrated. It has the following main reasons.
(1) Crankshaft bearings, connecting rod bearings and piston pores are severely worn, and the gap is severely exceeded, and the piston is impact the cylinder head under the action of the inertial force at the moment of the piston stroke transformation.
(2) Because of the replacement of the piston, or a fake product, the distance between the piston pin hole is greater than the original piston, and when the piston reaches the upper point, the cylinder head is collided due to ultra high .
In the way, if you encounter such a situation, the first aid method is to remove the cylinder head, plus a cylinder pad, enhance the cylinder head and the collision. However, when there is a repair condition, it should be repaired immediately to restore its good technical status.
2, the abnormal sound of the piston ring
The abnormal sound of the piston ring is mainly a metal knocking sound of the piston ring, the air leak sound of the piston ring and the abnormal sound caused by excessive carbon.
(1) Metal tap of the piston ring. After the engine has been working for a long time, the cylinder wall was worn, but the upper portion of the cylinder wall was in contact with the piston ring almost maintained with the original geometry and size, which allow the cylinder wall to generate a step. If the old cylinder pad or replacement new cylinder shield is thin, the piston ring in the work will collide with the steps of the cylinder wall, and a diabolous \"\" metal hit sound. If the engine speed rises, the abnormal sound will increase. In addition, if the piston is broken or the piston ring and the gap gap are too large, a large knocking sound can also be caused.
(2) The leakage sound of the piston ring. The piston ring is weak, and the opening clearance is too large or the opening overlaps, the cylinder wall is pulled or the like can cause the piston ring leakage. Its sound is a kind of\"drinking \" or \"\", and if you seriously leak, you will issue \"\" sound. The diagnostic method is to turn off when the engine water temperature reaches 80 ° C, which can be turned off to the cylinder into the cylinder, turn the crankshaft number, restart the engine, at this time, if the abnormal sound disappears, but soon If there is, it can be broken as a piston ring leakage.
(3) Excessive abnormal sound of carbon. When the carbon is over, the abnormal sound from the cylinder is a sharp sound, and the engine has an early symptoms because the carbon is burned red, and the engine has a nap premature symptom, and it is not easy to turn off. The formation of carbon in the active plug ring is mainly due to the sealing of the piston ring and the cylinder wall, the opening clearance is too large, the piston ring is reversed, and the loop coincidence is caused, which causes the lubricating oil, the high temperature high pressure gas is lower, in the piston The ring is combustion, causing the formation carbon or even sticking the piston ring to lose the elasticity and sealing of the piston ring. This fault can be excluded after replacing the appropriate piston ring of the specifications.
3, knocking on the tank
Knocking tank, refers to the moment when the piston starts at the working trip, or when the piston is uplink, the piston generated in the cylinder, its head and the skirt collide with the cylinder wall,\"Dangdang\" or \" The abnormal sound of \". If it is \"Dangdang\" sound, mostly caused by poor cylinder wall lubrication, at this time, it can be dripped into the cylinder, and then start the engine. If the noise is alleviated or disappeared, the abnormal noise is caused by poor lubrication. . If it is \"\" sound, at the same time, the exhaust pipe is blue smoke, which is generally due to the excessive gap between the piston and the cylinder wall. The main reason for the above situation has the following aspects:
(1) If there is this phenomenon only after the cold car is started. When the transportation is normal, it disappears because the piston is biased with the cylinder wall, and the cockroach is contracted, so that the two cooperates to further increase, thereby appearing the sound. After the mechanical temperature increases, the piston is expanded, the gap tends to normal, so the abnormal sound disappears. This situation does not have a big problem in the short term.
(2) The engine oil number does not match the requirements. When the engine is turned off, when the oil is started again, the oil is viscous, the liquidity is poor, and the cylinder wall cannot form a good oil film in a short time, the piston is directly collided with the cylinder wall and generates a knock. After a period of operation, the viscosity of the lubricating oil is normal, forming an oil film on the cylinder wall, and the abnormal sound is weakened or disappeared. As long as the lubricating oil is used reasonably, preheating the engine crankcase before starting, lubricates with mixed oil, then step on the starting rod before starting, so that the machine adheres more lubricants, this is avoid.
(3) Mixed gas entering the cylinder cannot
Normal combustion, produce early resistance or knockout, or the moment of fierce gates when the engine is not loaded, and the sound of the piston and the cylinder wall hit. The engine should be kept at normal temperature and use gasoline required to meet the octane. And appropriately adjust the ignition time.
(4) The piston skirt is worn, the cylindrical error is too large, and the piston is uplink, and the top will hit the cylinder wall, the piston is severely worn, and the gap between the two is in the middle. After decomposition, check, according to the situation, according to the situation, take the corresponding repair measures.
(5) Due to the bending of the link, the piston pin is deflected, the crank pin is not parallel to the piston pin, and the piston can cause the piston in the cylinder insensitable and hit the cylinder wall. This situation can only be decomposed, and the corresponding mechanism is replaced after diagnosis.
4, the tap of the piston pin
The piston pin and the piston pin hole, the piston pin and the connecting rod small head bushing (or bearing) gap is too large, and a sharp, crisp, tone is very high,\"\" metal knock, Similar to the sound of iron drill with small hammers. Its law is that the engine cold car is started, and the temperature is random, and the higher the temperature, the higher the temperature. If the ignition time is forward, the sound is accelerated and increased. If the spark plug is broken, the sound is weakened or disappeared.
Some engines are not only large, but the piston pin and the connecting rod small head bushing (or bearing) gap are also large. In this case, the sound of the tap sound is more complicated, and continuous \"buffer \"sound.
The cause of this fault causes the wear in the work to make the gap, and the three parts of the piston pin hole and the connecting rod small head liner are made of steel, aluminum, copper, and the expansion coefficient is very different. Take a little sloppy, the gap between the work will become larger than the heat expansion, causing the mutual impact. Moreover, when the gap is increased, the axial swift of the piston pin increases, and the pin of the pin will hit the pin ring, and an abnormal sound in the cylinder is increased.
5, the exhaustion of the valve
(1) The abnormal sound of the exhaust valve can be heard at the exhaust pipe muffler, such as \"唏唏 \" sound when the tire is seriously leaking. Valve leaks can be heard at the carburetor's upper mouth air filter, and its sound is like a young man, the voice,\"\" sound. The reason is that the valve is severely worn or ablated from the working surface of the seat, and the grooves and spots are can't be closely closed. Some is because the valve rod is too large or the tube clearance, so that the valve head cannot be centered and skew, resulting in leakage. If the gas springs are weak or broken, the valve cannot be bonded closely with the seat work surface, which will also cause leakage. In terms of assembly, if the valve rod is too small and the duct gap, the thermal expansion is thermally expanded, or the valve gap is too small, and the valve rod is hot and the valve is tightened or the rocker arm. It will cause the valve to completely shut down and leak.
(2) The abnormal sound when the valve spring is broken is different from the way of valve resettlement. After the side valve spring is broken, the sound of \"嚓 \" is issued while working, and if the pneumatic chamber cover will be clearer. After the upper valve spring is broken, the valve is automatically sinking, and it will hit the piston and the sound of\"Dangdang \" appears. If the latter is not turned off, it will cause a root piston, a broken link, and even more serious losses.
(3) Excessive gas percent can also cause an abnormal sound because there is excessive carbon, the carbon layer is hot, the piston temperature is high, the gap between the piston ring groove, the piston pin hole increases, thereby issuing a \"chatter \"The abnormal sound. This fault is often accompanied by an organic temperature, and the engine is not easy to turn off or cannot be turned off. The reason is that the oil ratio of oil in the mixed oil is over the combustion chamber, and the specific reasons should be further identified and excluded.
6, the abnormal sound of the combustion room
When the engine load increases, some engines issues \"\ \" sound from the cylinder head, different from normal operation, and even with acceleration performance. This sound volume is large and can be heard at 5-6m from the engine. It is especially obvious when sudden acceleration is, which can be regarded as an indication of the engine knock. When the flammable mixture is overflammable in the cylinder, it instantly releases a large amount of heat, resulting in sharp rise in the cylinder, and high pressure gas strongly impacts the top, cylinder head and cylinder wall, causing knocking. The main reasons for producing knocks, the engine is overheating, the ignition time is too early, the combustion chamber has excessive carbon, the octane of the gasoline is too low, the spark plug is low, which does not match the requirements.