Installation of connecting rod and piston group D-245
Check that the size group of the pistons set matches the size group of the cylinder liners
Pistons of one set on a diesel engine must be of the same size group corresponding to the size group of cylinder liners
Size group "B"
Piston skirt diameter 110-0.05-0.07 mm
Cylinder liner diameter 110+0.06+0.04 mm
Gap between piston and liner 0.09-0.13 mm
Size group "C"
Piston skirt diameter 110-0.07-0.09 mm
Cylinder liner diameter 110+0.04+0.02 mm
Gap between piston and liner 0.09-0.13 mm
Size group "M"
Piston skirt diameter 110-0.09-0.11 mm
Cylinder liner diameter 110+0.02 mm
Gap between piston and liner 0.09-0.13 mm
The difference in the mass of the pistons of one set should not exceed 10 g.
The difference in mass between connecting rods and pistons must not exceed 30 g.
Check that the size group of the connecting rod bearings matches the repair or nominal size of the connecting rod journals. The size groups of pistons and cylinder liners are shown in the table.
Before installing the pistons assembled with connecting rods and piston rings into the liners, wipe the cylinder liner mirror, the outer surface of the pistons, the working surface of the connecting rod bearing shells and the crankshaft journal with compressed air.
The non-roundness and tolerance of the profile of the longitudinal section of the hole in the bushing of the upper head of the connecting rod is 0005 mm.
When pressing in the bushing, its symmetrical position relative to the middle plane of the connecting rod must be ensured.
After boring, the surface of the upper head bushing hole should not have marks or burrs, the roughness of the machined surface should be Ra≤0.63 µm
On the upper surface of the bushing, one spiral or radial mark with a width of no more than 0.1 mm is allowed.
Cracks and risks are not allowed on the surface of the connecting rod bolt. The bolt thread must be clean, without nicks or burrs.
The surface of the piston pin should be free of marks, nicks and cracks.
The difference in the mass of fingers installed on one diesel engine should not exceed 10 g.
The non-oiled pin should rotate easily in the connecting rod due to hand effort, not have lateral swing and not fall out of the connecting rod under the influence of its own weight.
The radial clearance (clearance) between the piston ring and the control gauge for the upper compression ring should not exceed 0.02 mm on no more than 10% of the surface and no closer than 20° from the lock; and for oil scraper rings - ovality should be within 0.15-0.65 mm
The gap at the junction of the rings must be within 0.3-0.6 mm, and adjustment of this gap is not allowed.
The tensile strength of the rings when bending the ring is not less than 441 Nm.
It is recommended to assemble the connecting rod with the piston and pin using a special mandrel shown in Figure 3.
Each piston is equipped with an upper compression ring coated on the outer surface with chrome, two (or one) compression cone rings and one box-type oil scraper ring with a spring expander.
The compression cone rings on the end surface of the lock are marked top, which should face the piston bottom when installing the rings
The joint of the oil scraper ring expander must not coincide with the ring lock.
Oil scraper piston rings are installed with a mark (extrusion) applied on the surface of the ring 7-20 mm from the lock, to the piston bottom.
When the piston rotates in a horizontal position, the piston rings must move freely, without jamming, into its grooves and sink into them under the influence of their own mass.
The piston ring locks must be positioned at equal distances around the circumference.
The cylinder liner mirror, pistons with piston rings, crankpins and crankpin bearings must be lubricated with engine oil.
The locks of adjacent piston rings must be located at an angle of 180°.
To install the pistons into the block sleeve, you must use mandrels I 806.01.200 and I 804.01.200.
The tightening torque of the connecting rod bolt nuts should be within 180-200 Nm.
Axial play of the lower connecting rod heads on the connecting rod journals is allowed no more than 1 mm at any position of the crankshaft.
The new diesel engine has axial play in the range of 0.15-0.4 mm.
The turning torque of the crankshaft after tightening all the nuts of the connecting rod bolts should not exceed 60 Nm.
At TDC, the plane of the bottom of each piston should protrude above the top plane of the cylinder block by 0.3-0.55 mm.
The gap between the piston head and the liner at a distance of 3 mm from the upper plane of the block must be at least 0.2 mm.
