Removal of shatunno-piston group is carried out in the following sequence:

– remove a head of the block of cylinders (see подразд. 3.1.6), the oil pallet (see подразд. 3.1.10) and the oil pump (see подразд. 3.1.12);

– establish the cylinder No. 1 piston in the bottom dead point (NMT), having turned a cranked shaft. Put labels on a cover of the shatunny bearing and a rod for the subsequent their correct installation;

Fig. 3.31. Cranked shaft and details of shatunno-piston group: 1–cranked shaft; 2–loose leaf of the shatunny bearing; 3–bolt of fastening of a cover of a rod; 4–piston finger; 5–maslosjemny ring; 6–kompressionny ring; 7–piston; 8–lock ring; 9–plug of a head of a rod; 10-rod; 11-rod cover; 12-nut of fastening of a cover of a rod

– unscrew nuts 12 (fig. 3.31) of fastening of a cover of a rod and uncover 11;

– check a finger development existence in the top part of a wall of the cylinder;

– вытолкините the wooden handle of a hammer the piston 7 with a rod 10 assembled;

– establish a cover of the 11th rod on a rod and wrap nuts of the 12th fastening of a cover of a rod;

– remove pistons with rods assembled other cylinders;

– put labels of mutual position of pistons and rods. Inflow on a rod and a cover at assembly should be directed to a forward part of the engine;

– take out lock rings 8 of flutes in piston openings, put forward a piston finger 4 and remove a rod 10.

Cleaning and defektovka of pistons and rods. Carefully clear pistons with rods of oil. Remove piston rings 5 and 6 (see fig. 3.31 ) a special stripper. It is possible to apply to removal and old щуп. For this purpose shift a piston ring to the top part of the piston, raise one of its edges, to insert under it щуп and slowly lead round shchupy round the piston. When the ring leaves the flute, remove it up.

Clear pistons of a deposit. Clean flutes for piston rings a fragment of an old piston ring. Wash out pistons and rods in gasoline or kerosene, wipe them dry.

Fig. 3.32. Scheme of measurement of diameter of a skirt of the piston: 1–micrometer; 2–piston

Carefully examine each piston. In the presence of cracks on a skirt or round openings under a piston finger it is necessary to replace the piston. Measure diameter of a skirt of the piston by a micrometer at distance of 10 mm from its bottom edge in the plane, a perpendicular axis of an opening under a piston finger (fig. 3.32) . Values of diameter of pistons are specified in подразд. 3.1.1. Fast wear of skirts of pistons can be caused by an engine overheat. In this case it is necessary to check cooling and greasing systems.

The deposit on a lateral surface of pistons indicates break of gases in an engine case. The burn-out of the bottom of the piston or an obgoraniye of its edges specify that combustion of fuel occurred to a detonation which was a consequence of the wrong installation of a corner of an advancing of ignition.

Dot corrosion of the piston is caused by hit of cooling liquid in the cylinder as a result of breakdown of laying of a head of the block of cylinders.

Assembly and installation of shatunno-piston group is carried out in the following sequence:

– heat up the piston 7 (see fig. 3.31 ) in hot water (50–80 °C); establish in the piston a rod 10; check that inflow on a rod and an arrow on the piston are sent to one party; insert a piston finger 4 and establish lock rings 8;

Fig. 3.33. Measurement of a lateral gap between a piston ring and a piston flute

– check a lateral gap between a ring and a piston flute (fig. 3.33) . If the gap does not correspond demanded (see подразд. 3.1.1), it is necessary to replace a ring or the piston;

Fig. 3.34. Opilivaniye of the ends of piston rings

– check a gap in locks of piston rings. For this purpose insert a ring into the cylinder and drown it down on 15 mm by means of the piston. Measure a gap the shchupy. If the gap exceeds demanded (see подразд. 3.1.1), it is necessary to replace that ring. If a gap in the lock less demanded, it is possible to saw round the ring ends by means of a file clamped in a vice, as is shown in fig. 3.34 ;

– establish new piston rings 5 and 6 (see fig. 3.31 ) on pistons 7 by means of a special stripper. At installation the inscription of "TORAHS" on a ring should be directed to the piston bottom. It is possible to establish rings and with the help щупа, thus installation begin with the bottom maslosjemny ring;

– establish loose leaves 2 in a rod 10 and a cover of the 11th rod so that ledges of loose leaves entered into rod and cover grooves;

– turn a cranked shaft in the situation relevant to NMT of the piston of the cylinder No. 1;

– turn rings on the piston so that their locks were at an angle 120 ° to each other;

– grease with fresh engine oil of a wall of the cylinder No. 1, the piston with the piston rings established as appropriate, loose leaves 2 shatunny bearings and the corresponding shatunny neck of a cranked shaft;

Fig. 3.35. Piston installation with a rod assembled in the cylinder: 1–block of cylinders; 2–the adaptation for compression of piston rings; 3–piston

– establish the piston in the cylinder by means of the wooden handle of a hammer, compressing piston rings the special adaptation (fig. 3.35) . The arrow on the piston should be directed towards a forward part of the engine;

– establish a cover 11 (see fig. 3.31 ) according to labels on it and a rod, tighten nuts of the 12th fastening of a cover the moment of 30 N · m, then tighten nuts on 90 °;

– define axial люфт the bottom head of a rod with the help щупа (see подразд. 3.1.1);

– turn a cranked shaft and check smoothness of a course of the established piston;

– establish the remained pistons with rods;

– establish the oil pump (see подразд. 3.1.12), the oil pallet (see подразд. 3.1.10) and a head of the block of cylinders (see подразд. 3.1.6).