Citroen Xantia

since 1993 of release

Repair and car operation

Check of a condition of loose leaves of radical and shatunny bearings of a cranked shaft

Typical examples of wear of loose leaves of bearings of a cranked shaft

And — Are scratched by alien particles - the particles which have plunged into a working layer of the loose leaf are visible
In — the Lack of oil - the top layer is erased
With — Loose leaves are incorrectly located at installation - there are brilliant (polished) sites
D — the Neck is cramped on a cone - the top layer is removed from all surface
Е — Wear of edge of the loose leaf
F — Malfunction of "fatigue" - were formed craters or pockets

Despite obligation of replacement of loose leaves of radical and shatunny bearings in the course of performance of major maintenance of the engine, it is necessary to subject a condition of old loose leaves to attentive studying as on it it is possible to gather a lot of useful information about the general condition of the engine. Loose leaves of bearings are graduated on thickness and accessory to their this or that dimensional class is determined by color marking.

The exit of bearings out of operation can result from a lack of greasing, hit of dirt or extraneous particles, overloads of the engine, development of corrosion and other adverse effects. Examples of the most characteristic defects of loose leaves of bearings of sliding are given on an illustration Typical examples of wear of loose leaves of bearings of a cranked shaft. Regardless of the defect nature, the reason of its emergence should be revealed and eliminated prior to the beginning of engine assembly in order to avoid recurrence.

For survey take loose leaves from the beds in the block cylinders/case of the engine, radical and shatunny covers and the bottom heads of rods. Spread out the removed loose leaves on a pure equal working surface as an arrangement on the engine that it was possible to correlate their condition with a condition of the corresponding necks of a cranked shaft. Try not to touch working surfaces of loose leaves with hands in order to avoid casual damage of a soft material.

Dirt and extraneous particles get to the engine various ways. They can be left inside after completion of major maintenance, get via filters or system of ventilation of a case. Often dirt gets at first to impellent oil and already together with it gets into bearings. It is worth to remember that in the course of normal wear of the engine metal sawdust is inevitably formed. If after performance of recovery operations the due consideration is not given to procedure of cleaning of the engine, in it by all means there are abrasive particles. Regardless of a way of penetration into the engine, all extraneous particles appear sooner or later introduced in a soft surface of loose leaves of bearings of sliding and are easily distinguished at visual survey of the last. The largest particles usually do not get stuck tightly in loose leaves, but deep furrows and teases leave on their working surfaces and surfaces of the corresponding necks of a shaft. The best protection against emergence of such defects is the conscientious attitude to performance of cleaning of the engine after completion of major maintenance and installation during assembly only absolutely pure components. Also it is worth to remember need of performance of regular and frequent change of impellent oil.

Oil starvation also can be caused by several reasons which often have been closely interconnected with each other. That treat: an engine overheat (conducting to an oil razzhizheniye), overloads (as a result of which oil is forced out from bearings), leakages of oil (connected with excessive size of a working gap in bearings, wear of the oil pump, or excessive increase of turns of the engine), etc. Passableness violation маслотоков, more often connected with negligence of installation of components at the assembly conducting to a rassovmeshcheniye of oil openings, also causes reduction of supply of oil in bearings and, finally, to an exit of loose leaves out of operation. A characteristic sign of oil starvation is the wipe and replacement of a soft working layer of loose leaves from their steel substrate. Sometimes the temperature raises to such an extent that on a steel substrate as a result of an overheat violet spots are formed.

It is necessary to remember that essential influence on service life of bearings is rendered by a driving manner. Increase of load of the engine is promoted by frequent complete opening of a butterfly valve, movement on small turns, etc. As a result there is a replacement of an oil film from a working gap of bearings that conducts to a softening of loose leaves of the last and education on their working surface of small cracks (fatigue deformation). Finally there is an otsloyeniye of separate fragments of a material of a working layer and a vyryvaniye them from a substrate.

The driving manner also considerably affects service life of bearings. Movement with completely open butterfly valve, movement on a low gear conduct to strong overloads of bearings and squeezing from working gaps of an oil film. Thus the material of loose leaves is softened, and a working layer растрескивается. Such modification of bearing surfaces is called as fatigue deformation. As a result over time the working layer starts to separate fragments from a substrate and bearings become unfit for use.

Car operation in a city cycle is often connected with commission of a set of short trips that conducts to development of corrosion of bearings as insufficient warming up of the engine promotes loss in it of condensate and formation of caustic gases. Aggressive products accumulate in impellent oil, forming шлам and acid and as oil continuously arrives in bearings, finally, influence a material of loose leaves of the last, causing its oxidation and destruction.

The wrong installation of loose leaves at engine assembly also conducts to their fast destruction. At too dense landing it is inadmissible the size of a working gap that is at the bottom of oil starvation of bearings is reduced. Hit between backs of loose leaves and beds of bearings of extraneous particles conducts to formation of sites of an eminence of a working surface and destruction of the last in the course of normal operation of the engine.

As it was already mentioned above in this section, replacement of loose leaves at major maintenance of the engine should be made without fail, regardless of their condition (see. Installation of a cranked shaft and check of working gaps of radical bearings) - attempt to ignore this requirement is capable to lead only to seeming economy.