Fig. 3.37. Measurement of diameter of the cylinder 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 nutromery (fig. 3.37) . The scheme of measurement is shown in fig. 3.38 . If wear of walls of cylinders exceeds 0,08 mm, then it is necessary to chisel them to the following repair size and to install the corresponding repair pistons. Even if only one cylinder is worn-out, on the repair size all cylinders are processed. Rods replace in a set.

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

Before repeated installation the bent shaft needs to be cleared carefully, oil channels — to clean and blow compressed air. Be convinced of lack of traffic jams in them. For this purpose by means of a butterdish fill in oil in an opening of the oil channel — it has to leave other opening on the next neck. Any blockage of the oil channel should be eliminated before installation of a bent shaft.

Check a condition of inserts of conrod bearings. A sign of damage of conrod bearings is the regular rhythmical loud knock from a bent shaft. Its frequency depends on the frequency of rotation of a bent shaft. This knock is especially well listened during the operation of the engine with loading. It can be followed by oil pressure drop.

Fig. 3.39. Types of damages of inserts

Damage of the radical bearing is usually indicated by strong vibration, especially with a high frequency of rotation of a bent shaft. It is followed by more essential pressure drop of oil, than at wear of conrod bearings, and loud knock. Inserts of bearings in good shape have a smooth uniform opaque silvery surface. Types of damages of inserts are shown in fig. 3.39 . If inserts are damaged, and necks of a bent shaft in good shape, then it is necessary to establish new inserts of the same size. When grinding necks the corresponding repair inserts have to be established.

Damages of inserts can be caused by a lack of lubricant, existence in oil of dirt and foreign debris, an overload of the engine or corrosion. Before assembly of the engine it is necessary to remove the cause of an exit of their system of inserts. For example, one of the reasons is operation of the engine with a low frequency of rotation and high loadings when the oil pump does not provide normal pressure in the lubrication system, and oil is intensively squeezed out from a working zone. Frequent launches 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 the necks of a bent shaft working in contact with epiploons.

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

– clear inserts of beds of radical bearings, covers of bearings and a neck of a bent shaft;

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

– establish a bent shaft without preliminary lubricant of his necks and inserts of bearings;

– cut off 5 pieces of a core of Plastigauge. They have to be a little shorter than width of necks;

– establish covers of bearings with inserts on the places;

– tighten bolts of fastening of covers of radical bearings the required moment (see subsection 3.1.1). Do not rotate a bent shaft at all;

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

Fig. 3.40. Definition of a gap in the radical bearing: 1 – the deformed Plastigauge core; 2 – large-scale scale

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

– define values of a gap in other bearings;

– remove all traces of a core from necks of a bent shaft and inserts;

Wash out hot water under pressure all internal channels and cavities of the block of cylinders. Ask for the help on HUNDRED on the site sinks. Blow cavities and channels compressed air. Clear and blow 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.

Determine a gap between the piston and the cylinder by the probe 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 to the following repair size with installation of the corresponding pistons.