2.10.12. Conrod and piston group

Fig. 2.504. Components of the piston and rod: 1 – a bolt of fastening of a cover of a rod – 30 N · + to tighten m on 90 ° (1/4 about.); 2 – rod cover; 3 – bearing insert; 4 – rod; 5 – lock ring; 6 – piston finger; 7 – piston; 8 – piston rings; 9 – piston ring



Check of a thermal gap of piston rings

Fig. 2.133. Check of a thermal gap of a piston ring


Drive a piston ring from above, at right angle to a cylinder wall, to the lower opening of the cylinder, at distance about 15 mm from its edge (fig. 2.133).
For installation use the piston without rings.


Check of a gap of piston rings on height
Before check clear a ring flute of the piston.


Check of pistons
Measure approximately in 10 mm from bottom edge, at right angle to an axis of a piston finger.
Max. deviation from the nominal size: 0,04 mm

Adjusting situation and compatibility piston/cylinder

Fig. 2.505. Marking of adjusting provisions of pistons


The arrow indicates the bottom of the piston towards belt pulleys (fig. 2.505).

Check of diameter of the cylinder

Fig. 2.135. Scheme of check of diameter of the cylinder


Take measurements by means of a nutromer of 50-100 mm in 3 places cross-wise in the cross direction A and in the longitudinal direction B (fig. 2.135).
Max. deviation from the nominal size: 0,10 mm

The adjusting provision of inserts of bearings in rods

Fig. 2.506. The adjusting provision of inserts of bearings in rods



It is necessary to insert inserts of bearings into a rod or a cover of a rod in the middle.
Distance And = 2,5 mm.

Check of a vystupaniye of pistons in the top dead point

Fig. 2.507. Check of a vystupaniye of pistons in the top dead point



At installation of new pistons or a new component of the engine check a vystupaniye of all pistons in VMT.
Depending on a vystupaniye of pistons establish the corresponding laying of a head of the cylinder according to the following table.


Marking of laying of a head of the block of cylinders

Fig. 2.508. Marking of laying of a head of the block of cylinders: 1 – number according to the catalog of spare parts; 2 – code of management; 3 – openings


Watch rice 2.508.

NOTE
If at measurement of a vystupaniye of pistons various values were received, for compatibility with consolidation use the largest size.

Sizes of pistons and cylinders

Check of a radial beating of rods
Uncover rods.
Clear covers of bearings and a neck.
Put Plastigage thread according to bearing width on a radical neck and in inserts of bearings.
Put covers of rods and fasten with the moment 30 N · m, do not turn the crankshaft.
Again uncover rods.
Compare width of a measuring strip of Plastigage to a scale.
Radial beating.
Limit admission of 0,08 mm.
Replace bolts of rods.