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.
Valve ring
The valve foot ring is at low engine speed, the upper part of a rhythmic clear and uniform “Da Da” sound, and the sound speed increases, also increases. In addition, the noise does not change with _ and cylinder temperature off the oil change.
The reason
Improper adjustment of the valve foot clearance or adjustment of the screw nut.
Valve clearance adjustment screw or rocker arm wear.
Baotou North Benz parts cam wear is too large, the work of the tappet to produce jitter.
Baotou North Benz parts valve push rod deformation.
The diagnosis and treatment methods
The sound of the valve foot does not change with the change of temperature, but the sound frequency is changed with the speed. In the valve chamber cover and idle sound.
The single cylinder test will not affect the sound change.
In order to avoid the interference of the tapping sound at low speed, the method can be used to improve the speed and then close the throttle, while the engine speed down to listen to the method of diagnosis.
Open the cover of the valve chamber, and press the rocker arm with the hand to feel the vibration is relatively large.
The gap with a feeler inserted, the sound disappears when the valve foot ring.
The hands to press the rocker arm with up and down, if the sound diminished or disappeared, the valve rod and tube or rocker shaft and rocker clearance is too large.
If we have been identified as the valve clearance caused by excessive noise, should adjust the gap.
It is still a noise if adjusted, should check the wear Baotou Benz accessories cam (measuring cam top) and the push rod has no deformation. If wear or deformation should be replaced.