Mazda 626

1991-1998 of release

Repair and car operation

Causes of wear of bearings

In spite of the fact that radical and shatunny bearings at major maintenance of the engine are subject to obligatory replacement, old bearings should be stored in a place of their installation for careful check as wear tracks on these details allow to restore the general condition of the engine.

Causes of destruction of bearings of a cranked shaft are insufficient greasing, presence of dirt and extraneous particles, an overload of the engine and corrosion.

Irrespective of the reason which has caused destruction of bearings, it is necessary to eliminate it before final assembly of the engine to avoid repeated damages of these details.

Dirt and extraneous particles get to the engine for various reasons - in the course of assembly, via filters or system of ventilation of a case, through oil.

Often at pollution there are metal particles from machining of details of the engine, or owing to wear at normal operation of the engine. Sometimes at pollution there are remains of abrasive materials after carrying out pritirochny and grinding works, especially at insufficient washing and pro-cleaning. Irrespective of the origin reason extraneous pollution usually take root into a soft alloy of the bearing and are easily distinguishable.

Large particles cannot take root into the bearing and lead to emergence of scratches and задиров on surfaces as bearing and necks of a cranked shaft.

The best way of elimination of the reason of such wear is careful washing of details and maintenance of faultless purity in the course of engine assembly. For the prevention of premature wear also it is recommended to a thicket to change oil and filters.

Insufficient greasing of the engine can be caused by a number of the interconnected reasons. Overloads concern them (cause expression of oil from a surface of bearings) and pressure decrease because of leakage (emission) of oil (because of the raised gaps in bearings, wear of the oil pump, big frequency of rotation of a cranked shaft) an excessive overheat of the engine (causes razzhizheny oils). The reason of the accelerated wear of bearings of a cranked shaft also is blocking of oil channels, usually owing to a nesovmeshchennost of lubricant openings in the bearing and details of its case that causes insufficient greasing and failure. When a cause of destruction is insufficient greasing, there is a wipe or expression of a material of a covering of the bearing from a steel basis. The temperature increases to such level that from an overheat there is a vykrashivaniye of a steel basis of the bearing in blue color, possibility of deformations of covers of bearings and bolts of rods is not excluded.

The durability of bearings of a cranked shaft also essentially depends on skills of driving and nature of movement. Bearings test the raised loadings at movement with completely open butterfly valve, long driving on small speeds, at pro-slipping. At the raised loadings there is an expression of an oil film, bearings test flexural deformations at which microcracks (fatigue wear) are formed. As a rule, there is a separation of a covering of the bearing from a steel basis in the form of small particles. Trips on small distances can be at the bottom of corrosion wear of bearings as because of insufficient warming up skondensirovanny moisture and the gases causing corrosion do not manage to be removed. These components collect in oil, causing formation of acids and an insoluble precipitation. In process of intake of oil to bearings there is their corrosion under the influence of acids, causing their destruction and failure.

The exit of bearings out of operation can be caused also by the wrong installation in the course of engine assembly. Too dense landing is at the bottom of an insufficient lubricant gap and bad penetration of greasing. Dirt and the extraneous particles which have got under the back party of the bearing, cause its non-uniform prileganiye and premature failure.