2. The clearance between the bushings and the shaft journals can be checked using a calibrated plastic wire. To do this, clean the shaft journals and liners from oil, grease and other contaminants. Put pieces of calibrated plastic wire with a length equal to the width of the insert on the necks so that the wire does not block the lubrication holes. Install crankshaft, bushings and bearing caps. Tighten the cover bolts to the required torque, making sure that the shaft does not turn. Remove bearing caps. Determine the gaps between the bearing shells and the shaft journals along the width of the most flattened section of the wire using the scale printed on the wire packaging. If the clearance exceeds the maximum allowable value, replace the bearing shells. If it is not possible to obtain normal clearances by replacing the liners, grind the crankshaft journals to the repair size and install liners of the appropriate repair size.
3. The selection of the repair size of the connecting rod and piston group should be made according to the marks on the parts:
1) The position of the connecting rod mark.
2) The position of the crankshaft mark.
3) The position of the mark on the connecting rod bearing.
4) The selection of parts according to the group of repair sizes is made according to the table.
4. The letters embossed on the end of the cylinder block are the size mark for each of the four main bearings. Use these marks as well as the marks on the crankshaft to select the connecting rod bearings. The position of the marks for the selection of the main bearing shells:
1) The position of the marks on the cylinder block.
2) The position of the marks on the crankshaft.
3) The position of the marks on the main bearing shell.
4) The selection of parts according to the group of repair sizes is made according to the table.
5. If the connecting rods are reinstalled during assembly, make sure they are installed in the same cylinders in which they were before disassembly. If new connecting rods are installed, make sure that the connecting rod mark is on the same side as the insert lock. Replace the connecting rod if any visible damage is found or if excessive wear is evident on the connecting rod.
6. Using a special tool, check the connecting rods for bending or twisting. Allowable crank bend: 0.05 mm per 100 mm length or less. Allowable twist: 0.1mm per 100mm or less. If the amount of bending or twisting of the connecting rod is close to the permissible value, but still exceeds it, it is allowed to straighten the connecting rod with a press. If there is excessive bending or twisting, the connecting rod must be replaced with a new one.
7. Using a dial indicator, check the crankshaft axial clearance by moving it with a screwdriver along the cylinder block. Nominal axial clearance: 0.07 - 0.25 mm. Maximum allowable axial clearance: 0.30 mm. If the axial clearance exceeds the limit, replace the thrust bearings as a set. Thrust bearing thickness: 2.05 - 2.09 mm.
8. Using a micrometer, measure the diameter of each main and connecting rod journal of the crankshaft in the places indicated by the arrows in the figure. Nominal journal diameter: 61.982 - 62.000 mm. Nominal diameter of connecting rod journals: 47.982 - 48.00 mm.
9. Use a scraper to remove the remnants of the gasket from the surface of the cylinder block, and then thoroughly clean the entire cylinder block with a brush and solvent. Using a ruler and feeler gauge, check the flatness of the contact surface of the cylinder block at the locations indicated in the figure. Standard non-flatness value of the contact surface: less than 0.03mm. Maximum allowable non-flatness of the surface: 0.05 mm.
10. Visually check the cylinder mirror for scratches. If there are deep scratches, the cylinder liner must be replaced or bored out.
11. Using a bore gauge, measure the diameter of the cylinder at points A, B and C in mutually perpendicular planes. Nominal cylinder diameter: 86.70 -86.73 mm.
12. Check cylinder diameter marks (A) on the surface of the cylinder block.
13. Check size code (A) piston on its top surface.
14. Select the piston according to the repair size of the cylinder liner. When doing this, take into account that the gap between the piston and the cylinder: 0.01 - 0.03 mm.
15. In case of severe wear of the cylinder liner, oversized pistons should be selected according to the largest bore diameter of the cylinder liner. The repair dimensions of the pistons are increased by 0.25 and 0.5 mm, the corresponding marks are applied to the upper part of the piston.
16. Measure the piston diameter and calculate the new cylinder diameter:
New cylinder diameter = piston diameter + (0.01 - 0.03 mm clearance between piston and cylinder) - 0.01 mm (honing approval).
17. Rebore each cylinder to the calculated diameter and then honing.
18. Check clearance between piston and valve. It should be in the range of 0.01-0.03 mm.
Note. When boring at least one cylinder, bore all other cylinders to the same repair size.
19. Measure the main diameter of the piston with a micrometer (39 mm from the bottom). Nominal piston diameter: 86.68 -86.71 mm. In case of severe wear of the piston, it is necessary to replace it with a new one.
20. Use a feeler gauge to measure the gap between the new piston ring and the piston groove.
The side clearance should be:
- Piston ring No. 1: 0.04 - 0.08 mm;
- Piston ring #2: 0.03 - 0.07 mm.
The maximum allowable backlash is 0.1 mm for both piston rings.
If the side clearance is greater than the allowable value, replace the piston.
21. To check the clearance of the ring in the lock, insert the ring into the cylinder. Install the ring at right angles to the cylinder wall, pressing it lightly with the piston. Check the ring gap with a feeler gauge.
Lock gap:
- Piston ring No. 1: 0.20 - 0.35 mm;
- Piston ring No. 2: 0.37 - 0.52 mm;
- Oil scraper ring: 0.20 - 0.70 mm.
If the gap exceeds the maximum allowable in operation, replace the ring with a new one. When replacing rings without boring cylinders, check the gap in the lock by setting it in the lower, less worn part of the cylinder.
22. Measure the diameter of the piston pin with a micrometer. It should be 21.001-21.007 mm.
23. Measure the clearance between the piston pin and the piston. It should be 0.007-0.022 mm.
24. Check the difference between the piston diameter and the hole in the top of the connecting rod. It should be in the range of 0.016-0.033 mm.