Compared with the gasoline engine, diesel engine abnormal sound diagnosis is more difficult to grasp, this is decided by the structure characteristics and working characteristics of the diesel engine, such as compression ratio, thermal load, work is relatively rough, big noise, broken oil cannot instantly, and even some diesel oil at the opening of the position of the people not easy to close, to the diagnosis of abnormal noise also brings inconvenience. However, the abnormal sound of the diesel engine has its specific rules, as long as the analysis and comparison, look at the phenomenon of grasping the essence, it is possible to find out its regularity.
Piston knocking
Piston knocking cylinder will lead to engine fuel consumption is too high, channeling oil, oil consumption is too much, poor economy. When the piston hit the cylinder, the piston will be broken, and even damage the connecting rod and cylinder.
The upper part of the piston knock noise occurs in the engine cylinder, the piston stroke usually occurs in the beginning of the moment. Swinging piston in the cylinder or moving its head or skirt and the cylinder head or cylinder collision _ noise generation, its characteristics are: the engine running at idle speed, sound similar hammer, rhythmic “Dangdang” sound, clear. The sound changes with the temperature of the engine, and the sound is more obvious under low temperature. When the throttle suddenly, as a “quack” continuous metal percussion sound. If the cylinder has a knock, from idle speed to high speed, sound noisy disorder.
The reason
Baotou beiben parts of the piston and the cylinder wall clearance is too large.
The cylinder body and the ring are of poor quality. In addition to bad lubrication, the engine after a period of operation, the piston and cylinder wear serious, increases the gap of piston and cylinder, and the cylinder corresponding to the first air ring on at a serious level, so that the piston knocking cylinder a different sound.
Piston skirt and cylinder wear serious, resulting in the round and knocking cylinder.
The Baotou beiben bending or torsion deformation parts connecting rod, the piston in the cylinder is caused by the deviation, normal wear, make the piston slap.
The piston pin and connecting rod bushing with the tight.
The deformation of piston.
The bad lubrication.
The diagnosis and treatment methods
The open plus oil cover, engine speed adjustment in the abnormal sound of the most obvious and clear observation range, the oil outlet is the smoke exhaust pipe is used to take the blue smoke; in the upper part of a cylinder opener against the side of the valve rod, if touch piston knock, can be very similar to the same small hammer cement vibration sense.
Then the cylinder by cylinder oil, if broken into a cylinder, the sound was reduced or disappeared, and when the oil recovery and can hear the percussion sound, that is the piston of the cylinder cylinder matching gap is too large and percussion, should be promptly repaired.
The suspicious cylinder piston knock, the cylinder injector is unloaded, to add a small amount of oil cylinder, rotating laps crankshaft, and then put it back after starting the engine fuel injector, if knock reduction or disappearance of running for a while, knock again, can be confirmed to the cylinder knocking.
If the knocking sound occurs only in the cold car operation, the engine temperature is normal after the sound disappeared, can not continue to use, maintenance, etc. the appropriate time for repair.
If the Baotou beiben heavy duty truck accessories clear sound when the engine is cold, when the temperature rises, idling “quack” sound, accompanied by the chattering, and the higher the temperature is, the greater the noise, the deformation of piston or poor lubrication, should be promptly repaired.
The bad lubrication and knock, also should find out the reasons for lubrication failure shall be inspected.
Remove the cylinder cover, the piston is drawn out for inspection, if found serious loss, injury, circular cylinder connecting rod deformation should be carried out for repair parts.