How to deal with the abnormal noise of engine connecting rod bearing?
The main manifestations of abnormal noise of fag bearing of engine connecting rod: there is continuous and obvious knocking sound and abnormal noise when suddenly accelerating. This abnormal noise can be heard at idle speed, but it is obvious at medium speed and not obvious at high speed. After the cylinder with abnormal noise is cut off, the abnormal noise is obviously weakened or disappeared. When the engine temperature changes, the abnormal sound does not change.
The connecting rod bearing clearance is too small or the bearing quality is poor, and the alloy falls off, resulting in bearing burning and abnormal noise. Excessive fit clearance between connecting rod journal and connecting rod bearing is the main reason for abnormal sound of connecting rod bearing.
Poor lubrication causes burning of connecting rod bearing and abnormal sound of connecting rod bearing. The causes of poor lubrication are generally insufficient lubricating oil, blocked oil passage, or deterioration of lubricating oil.
when the vehicle is driving, if you can hear a small click when increasing the throttle, but when reducing the throttle or reducing the load, the abnormal sound can be reduced or disappeared, which is generally the initial symptom of abnormal sound of connecting rod bearing.
If you suddenly hear the abnormal sound of the engine running when the vehicle is running, it seems to be the sound made by drilling on hard steel parts with a large drill bit under the condition of lack of lubricant. This is generally the abnormal sound of burning NTN bearings without oil. When this abnormal noise occurs. If the bearing may be burned and hold the journal, stop the engine immediately, turn off the engine, and rotate the crankshaft for several turns with the handle to prevent the crankshaft from being held.
the engine can be idled. And the fire breaking test shall be carried out cylinder by cylinder. Then shake the throttle from idle speed to medium speed. When shaking the throttle, you can clearly hear the abnormal sound. There is an obvious cylinder loading phenomenon during the fire cut-off test. The abnormal sound can be sensitively recovered at the moment of re firing.
It can be concluded that the NSK bearing of the connecting rod of the cylinder has abnormal sound. When checking the abnormal sound of connecting rod bearing, do not shake the throttle too many times, and the engine running time should not be too long to avoid cylinder tamping accidents.
When the grindstone surface is in contact with the rough raceway surface, due to the small contact area and large stress per unit area, the “reverse cutting” effect of the bearing workpiece will be affected under a certain pressure, and some abrasive particles on the grindstone surface will fall off, resulting in new wear and debris.
At the same time, the bumps on the surface of bearing workpiece are quickly cut, and the bumps and grinding metamorphic layer are removed by cutting and reverse cutting. This stage is called the cutting stage, in which most of the remaining metal is removed.
With the continuous processing, the surface of NSK precision bearing workpiece is gradually ground. At this time, the contact area between the grindstone and the workpiece surface increases, the pressure per unit area decreases, the cutting degree decreases and the cutting capacity decreases.
At the same time, the pores on the surface of the grindstone are blocked and in a semi cutting state. This stage is called the half cutting stage of bearing finishing. In the half cutting stage, the cutting marks on the surface of the bearing workpiece become shallow and appear dark luster.