Fig. 3.37. Measurement of diameter of the cylinder by a nutromer

Fig. 3.38. Scheme of measurements of diameter of the cylinder: And, In – the directions of measurements; 1, 2, 3 – belts of measurements

Measure diameters of cylinders by a nutromer (fig. 3.37) . The scheme of measurement is shown on fig. 3.38 . If wear of walls of cylinders exceeds 0,08 mm, it is necessary to chisel them till next repair size and to establish the corresponding repair pistons. Even if only one cylinder is worn-out, for the repair size all cylinders are processed. Rods replace in a set.

Carefully clear a cranked shaft. Examine radical and shatunny necks of a cranked shaft. Measure by a micrometer diameters of necks and define deviations from a kruglost of each neck. Values of the repair sizes, admissible wear and the admission of a kruglost of necks are given in подразд. 3.1.1. At wear of necks, existence on them рисок or scratches, deviations from a kruglost all necks of a cranked shaft process the next repair size in repair shop.

Before repeated installation the cranked shaft is necessary for clearing carefully, oil channels — to clean and blow the compressed air. Be convinced of lack of jams in them. For this purpose by means of a butterdish fill in in an opening of the oil channel oil — it should leave other opening on the next neck. It is necessary to eliminate any blockage of the oil channel before installation of a cranked shaft.

Check a condition of loose leaves of shatunny bearings. A sign of damage of shatunny bearings is regular rhythmical loud knock from a cranked shaft. Its frequency depends on frequency of rotation of a cranked shaft. This knock is especially well listened at operation of the engine with loading. It can be accompanied by oil pressure drop.

Fig. 3.39. Types of damages of loose leaves

Damage of the radical bearing is indicated usually by strong vibration, especially at high frequency of rotation of a cranked shaft. It is accompanied by more essential pressure drop of oil, than at wear of shatunny bearings, and loud knock. Loose leaves of bearings in a good condition have a smooth homogeneous opaque silvery surface. Types of damages of loose leaves are shown on fig. 3.39 . If loose leaves are damaged, and necks of a cranked shaft in a good condition, it is necessary to establish new loose leaves of the same size. When polishing necks the corresponding repair loose leaves should be established.

Damages of loose leaves can be caused by a lack of greasing, existence of oil of dirt and alien particles, an overload of the engine or corrosion. Before assembly of the engine it is necessary to eliminate the reason of an exit of their system of loose leaves. For example, one of the reasons is engine operation at low frequency of rotation and high loadings when the oil pump does not provide normal pressure in greasing system, and oil is intensively squeezed out from a working zone. Frequent start-up of the engine and a trip on short distances lead to corrosion as the engine does not manage to get warm completely and water condensate on its details does not evaporate.

Check a condition of necks of the cranked shaft working in contact to epiploons.

Check gaps in bearings of a cranked shaft by means of a round plastic core of Plastigauge. For this purpose execute the following operations:

– clear loose leaves of beds of radical bearings, covers of bearings and a neck of a cranked shaft;

– establish loose leaves of beds of radical bearings in a bed on the places;

– establish a cranked shaft without preliminary greasing of his necks and loose leaves of bearings;

– cut off 5 slices of a core of Plastigauge. They should be a little shorter than width of necks;

– establish covers of bearings with loose leaves on the places;

– tighten bolts of fastening of covers of radical bearings the demanded moment (see подразд. 3.1.1). At all do not rotate a cranked shaft;

– unscrew bolts of fastening of a cover of the radical bearing No. 1 and uncover;

Fig. 3.40. Gap definition in the radical bearing: 1–the deformed core of Plastigauge; 2–large-scale scale

– remove the deformed core of Plastigauge and put it to the large-scale scale put on packing, determine by a scale a gap (fig. 3.40) ;

– define values of a gap in other bearings;

– remove all traces of a core from necks of a cranked shaft and loose leaves;

Wash out hot water under pressure all internal channels and cavities of the block of cylinders. Address for the help on HUNDRED sinks on a site. Blow cavities and channels the compressed air. Clear and blow the compressed air all carving openings. At damage of rounds banish an opening carving the corresponding tap.

Examine the block of cylinders on existence of cracks and corrosion.

Define a gap between the piston and the cylinder with the help щупа or subtraction from diameter of the cylinder of diameter of the piston. If the gap exceeds demanded, it is necessary to replace the piston or to process cylinders till next repair size with installation of the corresponding pistons.