2.2.20. Check of a condition of radical and shatunny bearings
In spite of the fact that at major maintenance radical and shatunny bearings are subject to replacement, former bearings should be kept for attentive survey as it can give valuable information on an engine condition.
||And — Scratches because of dirt: pollution is introduced in a bearing material
In — the Lack of oil: the site of contact is used up
With — the Wrong installation: the light polished sites
D — Konusnost of a neck: the site of contact is used up by the neck
Е — Lateral wear
F — Fatigue refusal: poles or teases
Failure of bearings occurs because of a lack of greasing, presence of dirt and other extraneous particles, an engine and corrosion overload. Irrespective of a cause of failure of bearings, before engine assembly the reason that did not repeat again, should be eliminated.
For survey remove bearings from the block of cylinders and from covers, take from rods and covers of rods, and then spread out on a pure surface in the same order in which they are established in the engine. It will allow to compare problems in bearings with the corresponding neck of a cranked shaft.
Dirt and other extraneous particles get to the engine different ways. They can remain in the engine at assembly, or get via filters, or system of ventilation of a case (PCV). Dirt can get to oil, and from it - in bearings. Often there are metal particles after stanochny processing and because of normal wear of the engine. Sometimes after polishing of components of the engine there are abrasive particles, especially, if details are not exposed to careful cleaning by the corresponding ways. Whatever was the source, these extraneous objects often appear introduced in a soft material of bearings and can be easily found. Large particles do not take root into the bearing, and put scratches or damages to the bearing and a neck. The best way to prevent such cause of failure of the bearing - carefully to clear all parts and at assembly to keep all components the irreproachably pure. Also frequent and regular replacements of oil and the filter are recommended.
(Or the greasing terminations) have a lack of greasing of the reasons some connected among themselves. An overheat (which reduces thickness of a layer of greasing), an overload (which squeezes out oil from a gap between sliding surfaces) and leakage of oil or its effluence (because of increase in gaps in bearings, wear of the oil pump or high turns of the engine) - all these reasons make the contribution to a lack of greasing. The corked channels of greasing appearing usually as a result of discrepancy of lubricant openings in the loose leaf of the bearing, also lead to insufficient greasing of the bearing and its failure. If a cause of failure of the bearing is the lack of greasing, the material of the bearing is used up or breaks from a steel substrate. The temperature can reach such point at which the steel substrate becomes from an overheat of dark blue color.
The manner of driving can have a certain influence on bearing service life. Driving with completely open throttle on small turns (overloading the engine) creates very big loadings which aspire to squeeze out an oil film on bearings. These loadings bend bearings that brings to emergence on a surface of bearings of thin cracks (refusal because of fatigue of metal). Sometimes the material of the bearing weakens in some places and breaks from a steel substrate. Short trips lead to corrosion of bearings as at insufficient warming up of the engine there is no removal of condensate and gases causing corrosion. These products gather in impellent oil, forming acid and шлам. When oil arrives in engine bearings, acid influences a material of bearings, leading to its corrosion.
Wrong at engine assembly installation of bearings also leads to failure of bearings. In hard bearings there is an insignificant gap for greasing that will lead to insufficient greasing. Dirt or the extraneous particles which have got on a back surface of the loose leaf of the bearing will lead to emergence of eminences on surface of the bearing which will cause refusal.