Technical data

57
4. ROUTINE REPAIRS
4.1. Main Guidelines for Disassembling and Reassembling the Diesel En-
gine
The pistons with connecting rods should be pulled out upward only. Before pulling the
pistons out, remove the scale from the upper portion of the cylinder sleeves.
When replacing the parts of the sleeve-piston group and crank mechanism pay attention
to the size groups of the parts.
The sleeves are divided according to their internal diameter and the pistons according to
the external diameter of their skirts into three size groups, as shown in Table 6. The group desig-
nation (Б=L, С=M and М=S) is marked on the inserting cone of the sleeve and on the piston
head.
Table 6
Group marking Sleeve diameter, in (mm) Piston skirt diameter, in (mm)
Б = L
4.33 (110
04,0
06,0


) 4.33 (110
08,0
06,0


)
С = M
4.33 (110
02,0
04,0


) 4.33 (110
10,0
08,0


)
М = S 4.33
+0.0008
(110
+0.02
)
4.33 (110
12,0
10,0


)
To complete a diesel engine select the pistons, connecting rods and piston pins of the
same weight group; the difference in the weights of the connecting rods together with the pistons
shall not exceed 1 oz (30 g).
The main and connecting-rod journals as well as crankshaft bearing inserts are manufac-
tured in two nominal sizes in accordance with Table 7.
Table 7
Nominal designation Shaft journal diameter, in (mm)
of inserts main connecting-rod
1H
2.963 (75.25
101.0
082.0


) 2.687 (68.25
096.0
077.0


)
2H
2.953 (75.00
101.0
082.0


) 2.677 (68.00
096.0
077.0


)
The crankshafts, the connecting-rod and main journals of which are manufactured according to
the second nominal size, have the following additional designation on the first sidepiece:
- "2K" – main journals of the second nominal;
- "2Ш" (“2Sh”) – connecting-rod journals of the second nominal;
- "2КШ" (“2KSh”) – connecting-rod and main journals of the second nominal.
As shown in Fig. 33, each piston is fitted with upper compression ring coated with chromium over
the external surface, two conic compression rings and one box-shaped oil ring fitted with spiral
steel extender. The conic compression rings have the marking “up” on the end surface at the lock,
which shall be faced to the piston head when mounting the rings. The joint of the oil ring extender
shall not be aligned with the ring lock.
The locks of the piston rings shall be arranged at equal distance over the circumference.