J6390 pump truck, the engine noise is relatively loud, why?
If you want to hear the sound of the engine, you must find a quiet place, because the sound insulation effect of better cars is ideal now. If you don't look at the engine tachometer and don't know that the car is in a burning state, you may turn the key and ignite again. When monitoring the engine, generally follow the following steps:
1. During engine starting, the starting motor should not have harsh sound; The engine idle "chug sound" is even and there is no abnormal sound; The idle speed is stable at about 850 rpm (please refer to the automobile manual for specific stable idle speed values).
2. Gently step on the accelerator to slowly increase the engine speed, and there should be no noise in the process. Individual models will vibrate at a fixed speed, that is, the whole body will vibrate (if the vibration of * * * is very slight, it should be normal), and the vibration phenomenon of * * * after this speed should be eliminated; After the engine speed exceeds the maximum power point speed, the sound is generally obvious, but there should be no metal rubbing sound.
3. Press the accelerator pedal quickly, and the sound of engine power improvement should be smooth and without stagnation; Carefully distinguish the engine speed sound. The main sources of noise are: valve sound (usually "click" sound), if it is large, it is suspected to jack up the valve; All kinds of belt rotation sounds (generally squeaky sounds), if loud, may be the friction between the belt and the body; It is doubtful whether the engine makes other rubbing sounds to cover up the sudden sound.
4. Find a suitable place and drive the vehicle for 5- 10 minutes under complicated road conditions. After stopping, the idle speed should remain unchanged and the sound should be the same as before.
5. Open the hood and listen to the sounds on both sides of the engine. At the same time, move the throttle control raft by hand, and then listen carefully to the sound of the engine according to the points mentioned above.
Processing method of strong noise:
1, step on the accelerator and find that the acceleration is not obvious, the power is insufficient, and the engine has hysterical sound. The most likely time is when the engine is hot, cold or short of oil. Of course, small displacement engines may also experience over-acceleration. I'm only talking about general displacement engines such as 1. More than five. The causes of such problems can be divided into air filter, spark plug, ignition wire, gasoline, gasoline filter, gasifier, oil pump and other problems. Check whether the air filter is dirty, whether the spark plug is old and needs to be replaced, whether the ignition coil is broken, and whether the gasoline is dirty, such as water in the oil circuit. And check the oil pump, carburetor and so on (if there is one in the car).
2. When driving, the acceleration is normal, and the ignition may be normal. However, if driving at a constant speed, it is found that the engine speed is too high, but it seems that the speed still cannot be raised. Try to check the coolant. If the oil pressure is too high or too low, check the oil pressure gauge. It is also possible that there is a problem with the ignition time setting, which will also cause such symptoms. As for the others, it may be an internal problem of the engine, such as EGR valve blockage.
3. The engine hisses, just like steam or air coming out of the engine. Generally, after hearing this sound, the engine will lose power quickly. Possible problem, engine overheating, check the cooling system. The exhaust system is blocked, and the vacuum tube leaks or breaks.
4. The engine will whir when accelerating, or it will appear when decelerating. In short, the sound will change with the change of speed. Possible cause: the power steering oil is insufficient and filled with oil. The generator bearing may be damaged. When there is a problem with the power steering pump and water pump, it will also produce similar noise.
There is a lot of noise in the exhaust pipe, which is very annoying. Sometimes similar sounds will come from the front section. The main problem is the exhaust system. Check whether the exhaust pipe is broken.
6. When the engine changes its speed, it will make a clicking sound, as if something is beating the metal. You may not hear it when you speed up, which may be due to the cylinder valve. Adjust the valve to change it. Lack of oil may also cause similar problems, and the oil pressure is relatively low, so it is necessary to check the oil pressure.
7. When you step on the accelerator pedal, you will hear the exhaust pipe bang. The sound may not be loud, and there will be no abnormal noise when driving, which will increase fuel consumption. It is recommended to check whether the muffler and exhaust pipe are damaged.
8, the engine has a kicking sound, like the sound of a pencil knocking on the table, the engine speed increases and the sound increases. Possible cause: There is dust in the engine. It is recommended to change the oil, filter the engine and clean the engine. There may be a valve problem.
9. There may be no problem during driving, and there will be a click when accelerating. It is recommended to check the ignition time setting. It may be that the engine is overheated, the engine is carbon-deposited, and the engine oil is not good, so it is necessary to add advanced engine oil.
10, sharp noise, similar to squeak. . . . . . . Cheap. . . . . I heard it from a distance, especially when the air conditioner is on, and it is more obvious when the weather is cold. Possible reasons: the drive belt slipped and the direction was hit too hard, reaching the limit. The belt is too loose, so tightening it can solve it.
1 1, when driving at a low speed, or when refueling the door, there will be a clank under the engine, especially when the weather is cold. It is recommended to raise the frame and check whether there is an insulation board between the exhaust pipe and the ground. It may be caused by the aging of the insulation board, which can be solved by replacing or removing it.