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:20. Checking the main and connecting rod bearings

Despite the fact that the replacement of loose leaves of radical bearings and rod produced in the process of new engine overhaul is mandatory, the state of the old must be subjected to scrutiny, as the analysis of the results can provide valuable information about the general state of the engine.

Typical defects crankshaft bearings.

Bearing failures can occur as a result of insufficient lubrication, the ingress of foreign particles, motor overload and corrosion effects. Whatever the nature of the causes of bearing failures, it must be removed before the assembly of the engine in order to avoid recurrence of the operation of the restored unit.

To check the status, remove the ear covers of main and connecting rod bearing beds in the engine block and the bottom heads of rods and place them on a flat, clean surface in the same order in which they were installed on the engine. This will associate the problem with the state of the corresponding bearing shaft necks.

Dirt and debris can enter the engine in different ways. They may be left in assembly or penetrate filters or crankcase ventilation (PCV), to get into the bearings with oil. Metal filings can be left after machining or developed in the course of normal operation of the engine. Abrasive particles are often left in the engine after the recovery procedures, especially if you do not give due attention to cleaning the unit and internal components. Regardless of the method of penetration into the engine, dirt and debris as a result more likely to be embedded in a soft material bearing which can be easily identified. Large particles do not get stuck in the bearings, and leaves deep scars on the surface of the insert and shaft necks. The best preventive measure for prevention of bearing failures is a conscientious attitude to cleaning the engine and its components renovated using recommended methods of its implementation. Equally important is regular and frequent change of motor oil and oil filter.

Lack of lubrication (or stop) may be caused by multiple, often inter-related, reasons. These include: overheating (leading to a thinning of the oil layer), motor overload (resulting in the displacement of the oil layer of the gaps in the bearings) and maintenance of oil from backlashes of bearings (due to too much of their value deterioration of the oil pump or excessive engine speed). Violation maslotokov cross, which most often occurs as a result of misalignment of oil hole liners and beds, also leads to oil starvation and bearing failures. When the cause of bearing failure is a lack of lubrication, soft surface layer pads are usually forced out of the steel substrate. Sometimes the temperature rises to values such that the substrate becomes bluish.

Significant impact on the service life of the bearings has also driving style. Full opening flap when driving at low speeds results in a significant increase in the load on the bearings, which results in squeezing the oil film from the clearances. Such overload lead to a strong buckling liners and the formation of fine cracks on them (fatigue stress). Over time, there is a separation of individual pieces of soft liner layer from the steel substrate. Using the vehicle for movement over short distances leads to corrosion of the bearings as a result of insufficient warming up the engine, which cause condensation and corrosive gases. These products build up in the engine oil, forming acid and sludge. When such oil enters into the bearings acid starts to corrode the surface, leading to corrosion of the material.

Improper installation of bearings during assembly of the engine and can cause rapid their failure. Tug bearing a reason to insufficient quantities of gaps and, as a consequence, leads to oil starvation bearings. Contact between the back of the bed liner and bearing foreign particles when installing bearings leads to the formation of elevations bearing surface, which later becomes the cause of bearing failures.