2. Using a scraper, to clear a contact surface of a head of the block of cylinders of the lining remains.
3. Clean the bolt holes of soot and grease with compressed air.
4. Using a scraper, clean the contact surface of the cylinder block of gasket residue.
5. Clean the surfaces of the combustion chamber from carbon deposits with a metal brush.
6. Using a soft brush and solvent, clean the cylinder head completely.
7. Use a scraper to remove carbon deposits from the valve heads. Using a wire brush, thoroughly clean the valves.
8. Using a ruler and feeler gauge, check the cylinder head for warping by measuring in the directions shown in the figure. Standard non-flatness of the contact surface of the cylinder head: less than 0.03 mm, the maximum allowable non-flatness value: 0.06 mm.
9. Check combustion chambers, inlet and outlet channels, contact surface for cracks. If cracks are found, replace the cylinder head.
10. Using a bore gauge, measure the inside diameter of the valve guides at the locations shown in the figure.
11. Using a micrometer, measure the diameter of the valve stem at the locations shown in the figure.
12. By subtracting the diameter of the valve stem at the corresponding point from the inner diameter of the guide sleeve, determine the amount of clearance between the guide sleeve and the valve.
Nominal clearance between guide sleeve and valve:
- Inlet: 0.020-0.050 mm;
- Graduation: 0.030-0.065 mm.
Maximum allowable clearance between guide sleeve and valve:
- Inlet: 0.1mm;
- Graduation: 0.13 mm.
If the clearance exceeds the limit, replace the valve and valve guide.
13. Measure the chamfer angle of the valve. Check the degree of wear of the chamfer of the valve and, if necessary, replace the valve with a new one.
14. Measure the thickness of the valve head. Standard valve head thickness:
- Intake: 1.0mm;
- Exhaust: 1.3 mm.
Maximum allowable valve head thickness:
- Inlet: 0.5mm;
- Exhaust: 0.8mm.
If the thickness of the cylindrical part of the valve head is less than the maximum allowable, replace the valve with a new one.
15. Check valve stem wear, replace if necessary. -
16. Check the valve seat for signs of overheating. Check valve seat tightness. Replace valve seat if necessary.
17. Before reboring the valve seat, check the valve guide for wear. Replace guide bushing if necessary. The boring of valve seats is carried out on grinding machines, as well as using reamers. The dimensions of the valve seat in this case must correspond to the nominal ones and ensure a tight fit of the valve.
18. Using a square, check the vertical deviation of each valve spring. If the deviation from the vertical is more than 3°, replace the spring.
19. Check the free length of the spring. Replace springs that are not the correct length (42.5 mm).
20. Using a micrometer, measure the height of the intake and exhaust camshaft cams. The standard value for the height of both intake and exhaust valves: 43.95 - 44.15 mm. If the height of any of the cams is less than the minimum limit, the camshaft must be replaced.
21. Using a micrometer, measure the diameters of the camshaft bearing journals. Nominal diameter of the camshaft bearing journals: 25.964 - 25.980 mm. If the diameter of the bearing journals does not correspond to the nominal diameter, check the clearance between the bearing journals and bearings.
22. Check thrust bearings for delamination and wear. In case of damage to the bearing, the bearing caps are replaced complete with the cylinder head.
23. Check clearance between camshaft journals and bearings. For this:
- 1) Clean bearing caps and bearing journals.
- 2) Insert camshaft into cylinder head.
- 3) Place a calibrated plastic clearance gauge along the camshaft bearing journal.
4) Install the bearing cover.
5) Remove bearing cover.
6) Determine the gap between the bearing shell and the camshaft bearing journal by the width of the most flattened section of the wire using the scale printed on the wire package. If the gap exceeds the limit, replace the camshaft. If necessary, replace bearing caps complete with cylinder head.
7) Remove the remnants of the calibrated wire.
24. Install the dial gauge as shown. Measure the camshaft end play by moving it back and forth along the cylinder head. Nominal axial clearance: 0.1-0.15 mm. If the axial clearance exceeds the upper limit, replace the camshaft. If necessary, replace bearing caps complete with cylinder head.
25. Remove the camshaft from the cylinder head.