Removal of conrod and piston group is carried out in the following sequence:

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

– install the cylinder No. 1 piston in the lower dead point (LDP), having turned a bent shaft. Put tags on a cover of the conrod bearing and a rod for the subsequent their correct installation;

Fig. 3.31. Bent shaft and details of conrod and piston group: 1 – bent shaft; 2 – insert of the conrod bearing; 3 – bolt of fastening of a cover of a rod; 4 – piston finger; 5 – oil scraper ring; 6 – compression ring; 7 – piston; 8 – lock ring; 9 – rod head plug; 10 – rod; 11 – rod cover; 12 – nut of fastening of a cover of a rod

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

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

– you vytolkinit the wooden handle of the 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 of other cylinders;

– put tags of mutual position of pistons and rods. Inflows on a rod and a cover at assembly have to 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 troubleshooting 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 use to removal also the old probe. For this purpose shift a piston ring to the top part of the piston, raise one of its edges, to insert under it the probe and slowly lead round the probe around 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 around openings under a piston finger the piston needs to be replaced. Measure diameter of a skirt of the piston by a micrometer at distance of 10 mm from its lower 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 subsection 3.1.1. Bystry wear of skirts of pistons can be caused by an engine overheat. In this case it is necessary to check cooling systems and lubricants.

The deposit on the side 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 indicate that combustion of fuel happened to a detonation which was a consequence of the wrong installation of a corner of an advancing of ignition.

Pointed 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 conrod and piston group is carried out in the following sequence:

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

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

– check a side gap between a ring and a flute of the piston (fig. 3.33) . If the gap does not correspond demanded (see subsection 3.1.1), the ring or the piston need to be replaced;

Fig. 3.34. Trimming 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 by the probe. If the gap exceeds demanded (see subsection 3.1.1), then the ring needs to be replaced. If the gap in the lock is less demanded, then it is possible to saw round the ends of a ring by means of the file clamped in a vice as shown in fig. 3.34 ;

– install new piston rings 5 and 6 (see fig. 3.31 ) on pistons 7 by means of a special stripper. At installation inscription "TORAHS" on a ring has to be directed to the piston bottom. Rings can be established also by means of the probe, at the same time begin installation with the lower oil scraper ring;

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

– turn a bent shaft in the situation corresponding 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;

– oil fresh engine walls of the cylinder No. 1, the piston with the established appropriately piston rings, inserts 2 conrod bearings and the corresponding conrod neck of a bent shaft;

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

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

– establish a cover 11 (see fig. 3.31 ) according to tags 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 °;

– determine an axial side play of the lower head of a rod by the probe (see subsection 3.1.1);

– turn a bent shaft and check smoothness of the course of the installed piston;

– install the remained pistons with rods;

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