85425ea0 Survey of radical and conrod bearings

Typical defects of bearings

Even while radical and conrod bearings are subject to replacement at capital repairs of the engine, they need to be examined carefully as they can give valuable information concerning a condition of the engine.

Failure of the bearing can happen because of a lack of lubricant, presence of dirt or other foreign debris, an overload of the engine or corrosion. Irrespective of the reason of failure of the bearing, it has to be eliminated before the engine repeatedly gathers.

At survey of bearings remove them and spread out in the same order in what they were established on the engine. It will allow to define the corresponding neck of a bent shaft and will facilitate search of malfunctions.

Foreign debris can get to the engine in various ways. Metal particles can be in engine oil as a result of normal wear of the engine. Small particles together with engine oil can get to bearings and easily take root into soft material of the bearing. Big particles, getting to the bearing, will scratch the bearing or a neck of a bent shaft. The best prevention of failure of the bearing for this reason: carefully clear all internal surfaces of the engine and you keep them clean at assembly of the engine. Also frequent and regular replacement of oil with the filter is recommended.

Insufficient lubricant of necks of a bent shaft can be caused by the different reasons, such as high temperature of oil, an overload of the engine and leak of oil.

The driving manner the car also exerts impact on durability of the bearing. Completely open butterfly valve at low turns of the engine creates high load of bearings and expression from a zone of contact of an oil film. These loadings lead to emergence of cracks in a working part of the bearing that weakens the bearing and can lead to a separation of an antifrictional layer from a steel basis.

The movement on short distances leads to corrosion of bearings as a result the engine does not come to the stabilized working temperature at which water vapor and corrosion gases are removed. These couples and gases, being condensed in engine oil, form acid and a deposit. Acid together with engine oil gets to bearings, and corrosion of bearings begins.

The wrong selection of bearings at assembly of the engine also leads to failure of bearings. The bearings installed with a preliminary tightness leave an insufficient working gap of the bearing therefore there is no butter layer for lubricant.