Clear the piston of a deposit and remove all adjournment from lubricant channels of the piston and a rod. Carefully examine all details. Cracks of any character on the piston, piston rings, a finger, on a rod and its cover are not supposed. If on them there are teases, scratches or wear tracks it is necessary to replace these details. At piston survey:

Fig. 62. Backlash measurement between piston rings and ring flutes in a piston head

- Measure a backlash between piston rings and ring flutes in a head of the piston by means of a set щупов (fig. 62). The nominal backlash for top and bottom компрессионных rings 1 (fig. 63) makes 0,02—0,07 mm, and for маслосъемного 2 rings — 0,02—0,06 mm. Maximum permissible backlashes at deterioration — 0,15 mm. If there is a backlash are worn out either a ring, or a ring flute of the piston;

Fig. 63. Details of piston group: 1 — компрессионные piston rings; 2 — маслосъемное a ring; 3 — the piston; 4 — a rod cover; 5 — a bolt of fastening of a rod; 6 — rod loose leaves; 7 — a rod; 8 — the block of cylinders; 9 — a lock ring; 10 — a piston finger; arrow A specifies a direction to a forward part of the engine

- By turns insert all piston rings, since bottom rather картера into a cylinder aperture. Having turned one of pistons an underside, press through rings approximately on 15 mm downwards. After that they will appear directly in a cylinder aperture;

Fig. 64. Measurement of a backlash of locks of piston rings in a cylinder aperture

- Insert into cut of a piston ring — in the lock, measuring щуп to define a backlash (fig. 64). At компрессионных piston rings the backlash in the lock should be 0,2—0,40 mm, and at маслосъемного rings — 0,25—0,50 mm. A maximum permissible backlash at deterioration at all rings — 1,0 mm;

- If the backlash in the lock is too small (for example, at new piston rings which also should be measured) it needs to be increased. Rings are very fragile, therefore such work should be spent cautiously. Is better to clamp a file in a vice and to grind off the ring end;

- Check up on deterioration and teases piston fingers and plugs of rods. Even if only one rod has damages, it is necessary to replace all knot in gathering;

- Bolts of fastening of a rod on engine VR6 are screwed up directly in rods (it is not used any nuts) and represent so-called «pliable screws» with which it is necessary to replace after each untwisting;

- Check up rods by means of the measuring device on twisting and a bend.