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    Causes and solutions of diesel engine cylinder knocking

    2021-11-29 | Pageviews: CHANGZHOU FOAN M AND E CORPORATION
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    Causes and solutions of diesel engine cylinder knocking

    The symptoms of cylinder knocking of diesel engine during operation are: from medium speed to low speed, it will make a heavy cylinder knocking sound, the exhaust pipe emits black smoke, and sometimes there is gunfire or outward fire, and the engine body is overheated. The main causes of cylinder knocking are:

    1. The oil supply time is too early
    When the piston of the diesel sleeve engine moves upward and does not reach the specified injection position, the fuel injector starts to inject fuel to advance the fuel combustion. The high-pressure gas in the cylinder strikes the piston and makes a rhythmic "Da, Da" crisp cylinder knocking sound. Reduce the throttle and the cylinder knocking sound is obvious.
    The troubleshooting method is: adjust the fuel supply advance angle, that is, increase the gasket between the fuel injection pump and the gearbox to delay the fuel supply time to the specified fuel injection time. The oil supply advance angle can be delayed by 1.3-1.7 for each 0.1mm increase in gasket.

    2. Poor fuel combustion
    Low fuel injection pressure, fuel injector dripping, poor fuel injection atomization and too late fuel supply time will cause poor fuel combustion and cylinder knocking. The cylinder knocking caused by such faults is low and hoarse, accompanied by engine overheating, black smoke or exhaust pipe blasting, fire spraying and other phenomena. The fuel injector shall be removed for inspection and adjustment, the fuel supply time shall be adjusted, and new parts shall be replaced if necessary to make it meet the regulations.

    3. The oil outlet valve is worn
    After the oil outlet valve is worn, on the one hand, the fit gap between the pressure reducing ring belt and the inner hole of the valve seat becomes larger, the sealing performance becomes worse and the pressure reducing effect becomes worse; On the other hand, the residual pressure in the high-pressure oil pipe is too high and the oil supply increases, resulting in fuel deflagration and cylinder knocking. The cylinder knocking sound is particularly obvious when the throttle is reduced.
    The elimination method is to replace the oil outlet valve and valve seat. It should be reminded to the operator that the diesel engine in good technical condition sometimes makes a rhythmic knocking sound during low-speed operation, which is caused by the vibration wave caused by the sharp increase of air flow pressure during fuel combustion. Shunshui is the cylinder knocking mentioned above.



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