2.2.15.17. Check of the piston

ATTENTION The piston, piston ring and rod do not understand usual practice. When replacing the piston the piston finger, a piston ring and a rod are replaced together as a uniform element.

Fig. 2.162. Measurement of diameter of the piston

Measure the outer diameter of each piston at right angle 90 ° to a piston finger 10,0 mm higher than the piston (fig. 2.162).

If diameter of the piston – is less than norm, replace the piston, a piston finger, a piston ring and a rod assembled.

Diameter of the L8 piston:

82,965–82,995 mm;

LF, L3, L3 (with the mechanism of change of phases of gas distribution):

87,465–87,495 mm.

Measure a gap between the piston and the cylinder.

If value does not meet standard, replace the piston, a piston finger, a piston ring and a rod assembled.

Normal gap: 0,025–0,045 mm.

Maximum gap: 0,11 mm.

Fig. 2.163. Measurement of a gap between a piston ring and a flute of a ring

Measure a gap between a piston ring and a flute of a ring on all circle of the piston (fig. 2.163).

If the gap exceeds maximum, replace the piston, a piston finger, a piston ring and a rod assembled.

Normal gap:

- top: 0,03–0,08 mm;

- the second: on 0,03–0.07 mm;

- oil scraper: 0,03–0.07 mm.

Maximum gap:

- top: 0,17 mm;

- the second, oil scraper: 0,15 mm.

Fig. 2.164. Measurement of a gap of a piston ring

Insert a piston ring into the cylinder and, pressing a ring the piston, displace it in the lower point. Measure a gap in the lock of each piston ring by the probe (fig. 2.164).

If the gap exceeds maximum, replace the piston, a piston finger, a piston ring and a rod assembled.

Standard gap:

- top: 0,16–0,31 mm;

- the second: 0,33–0,48 mm;

- oil scraper: 0,20–0,70 mm;

- maximum gap: 1,0 mm.