Contents: Removal ↡ Installation ↡
Removal
1. Remove the cylinder head 5 (figure 3.12).
2. Remove the injector holders as an assembly.
3. Measure the diameter of the disc B of all valves (engines up to number 039739).
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4. Measure the diameter of the B-plate of all valves and the permissible difference between the stem diameters of both intake valves (engines starting from number 039740).
5. Remove plate 2 and springs 3 and 4.
6. Remove and mark valves 6 and 7 from the cylinder head.
7. Remove the valve stem seal 9. During installation, the seals must be replaced.
8. Measure the width of each ring of all valve seats.
9. Check the valve guide wear with a micrometer.
10. Check the concentricity and permissible deviation from the specified size of valves 6 and 7.
11. Check the springs of valves 3 and 4. The valve sizes are given in Table 3.2, the valve guide sizes are given in Table 3.3.
Installation
12. Installation is carried out in the reverse order of removal.
Figure 3.12. Valves: 1 - Rusks; 2 - Spring plate; 3 - Inlet valve spring; 4 - Exhaust valve spring; 5 - Cylinder head; 6 - Inlet valve; 7 - Exhaust valve; 8 - Valve puller with adapter; 9 - Valve stem seal; 10 - Pointer indicator; 11 - Indicator support; 12.1 - Support; 12.2 - Cartridge; 12.3 - Thrust fork; 12.4 - Removable fork; A - Valve plate angle; B - Valve plate diameter; C1 - Valve length (engines 904.908 up to number 03739); C2 - Valve length (engines 904.908 starting with number 039740 and 904.914/923/936); E - Valve stem diameter; P - Valve seat width; 3 - Valve seat diameter; H - Valve seat lapping distance by average diameter
Table 3.2. Valve dimensions
| Parameters | Engines up to number 026066 | Engines starting from number 026067 | |
| Valve fit to cylinder head contact surface, mm | 1.1-1.5 | ||
| Valve plate angle A,° | Inlet | 20 | |
| Outlet | 45 | ||
| Valve plate diameter B, mm | Inlet | 33.9-34.1 | |
| Outlet | 37.9-38.1 | ||
| Valve plate width P, mm | Inlet | 3.3-4.3 | |
| Outlet | 3.5-4.2 | ||
| Valve length C, mm | Inlet | 125.7-126.1 | 125.65-126.95 |
| Outlet | 152.5-152.9 | ||
| Valve stem diameter E, mm | Inlet | 7.935-7.950 | |
| Outlet | 7.925-7.940 | ||
| The lapping distance of the inlet valve seat (H) by the average diameter in relation to the diameter of the inlet valve seat (6). mm | Distance G | 31.0 | |
| Distance H | 2.7-3.1 | ||
| Lapping distance of the exhaust valve seat (H) by average diameter in relation to the diameter of the exhaust valve seat (C), mm | Distance G | 36.0 | |
| Distance H | 2.5-3.2 | ||
| Valve Stem Tip Hardness, VAT | Inlet | 54-60 | |
| Outlet | 54-60 | ||
Table 3.3. Valve guide bushing dimensions
| Parameters | Engines 904 | |
| Inner diameter in cylinder head, mm | 8.000-8.022 | |
| Valve stem runout, mm | Inlet | 0.050-0.087 |
| Outlet | 0.060-0.097 | |