BMW 3 series E30

Since 1983-1994 of release

Repair and car operation

3.2.23. Check radical and шатунных bearings

THE GENERAL DATA

Kinds of deterioration radical and шатунных bearings

A. Scratches because of dirt hit B. Insufficient greasing S.Nepravilnaja installation of bearings D. Deterioration because of конусности necks

E.Obrazovanie of a facet on a bearing edge F. Fatigue deterioration

Radical and шатунные bearings at engine major repairs are subject to the obligatory replacement, however the bearings which were in operation should be checked up carefully to restore the general condition of the engine at the moment of repair.

Sources of rupture of bearings of a cranked shaft are insufficient greasing because of wrong assemblage, pollution and penetration of extraneous particles, frequent overloads of the engine, corrosion, etc. Irrespective of the reason which have caused destruction of bearings, it should be eliminated.

At check of a condition of bearings they should be got from the block of cylinders, covers of radical bearings of a cranked shaft, шатунных covers and rods. Lay out loose leaves on a pure surface in the same order in which they have been established on the engine.

The dirt and extraneous particles get to the engine for various reasons – in the course of assemblage, through filters or ventilation system картера. Pollution can get also to oil, and from it – in bearings. Frequently at pollution there are metal particles from machining of details of the engine, or owing to deterioration at normal work of the engine. Sometimes at pollution there are rests of abrasive materials after carrying out притирочных and grinding works, especially at insufficient washing and procleaning of the engine after their termination. 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 occurrence of scratches and задиров on surfaces as bearing and necks коленвала.

Insufficient greasing of the engine ("oil starvation") can be caused variety of the interconnected reasons. Overloads concern them (cause expression of oil from a surface of bearings) and pressure decrease because of leak (emission) of oil (because of the raised backlashes in bearings, deterioration of the oil pump, the big frequency of rotation of a cranked shaft) an engine overheat (causes разжижение oils).

The durability of bearings of a cranked shaft also essentially depends on skills of driving. Bearings test the raised loadings at movement with completely open throttle заслонкой, or with small speed on the raised transfer (in the heavy engine modes). At the raised loadings there is an expression of an oil film. Bearings test изгибные deformations at which microcracks (fatigue deterioration) 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 deterioration of bearings as because of insufficient warming up the moisture and the gases causing corrosion have not time to leave сконденсированная.

Wrong installation of bearings at assemblage also leads to their premature deterioration. If the backlash in bearings is less than norm their greasing is complicated that leads to deterioration as well as owing to "oil to starvation". The dirt or the small particles which have got under the loose leaf of the bearing, lead to a local raising of the loose leaf and to the strengthened deterioration in this part.