5.8.4. Dismantling, repair and assembly of a head of the block of cylinders

If repair of a head of the block of cylinders of the engine installed on the car is necessary remove it (see. "Replacement of laying of a head of the block of cylinders"). In most cases repair of a head of the block of cylinders consists in grinding in or replacement of valves, grinding of saddles of valves. At such malfunctions as violation of tightness of channels of a shirt of the cooling system and a buckling of a privalochny surface to the block of cylinders, the head of the block is replaced.

It will be required to you: keys "on 10", "on 12", "on 13", a candle key, the magnetized screw-driver (or tweezers), the device for compression of valvate springs.

1. Remove a head of the block of cylinders from the car (see. "Replacement of laying of a head of the block of cylinders").

Fig. 5.5. Sequence of an otvorachivaniye of nuts and bolts of fastening of an inlet pipe

2. Remove press levers of valves and the directing crackers of levers (see. "Replacement of hydrocompensators of gaps in the drive of valves").

3. Turn off ten bolts and nuts of fastening of an inlet pipe in the sequence shown in fig. 5.5 remove from hairpins an inlet pipe assembled with a fuel stage, throttle knot and hoses of the cooling system …	4. … and its laying.

5. Turn out three bolts of fastening of the thermoscreen of a final collector (see. "Removal and installation of thermoscreens") also remove the thermoscreen.

Fig. 5.6. Sequence of an otvorachivaniye of nuts of fastening of a final collector

6. Turn off eight nuts of fastening of a final collector in the sequence shown in fig. 5.6.

7. Remove a final collector and the laying established under it from hairpins.	8. Turn out spark plugs (see. "Replacement and service of spark plugs").

9. Turn out two bolts of fastening of a cover of the thermostat and remove the thermostat (see. "Removal and installation of the thermostat").

10. If necessary turn out the sensor of temperature of cooling liquid of a control system of the engine from a block head (see. "Check and replacement of sensors of a control system of the engine").

11. Install the device for compression of springs of valves, squeeze springs …

Fig. 5.7. Installation of device for compression of springs of valves: 1 – head of the block of cylinders; 2 – device for compression of springs

    

GOOD ADVICE For compression of springs of valves of the head of the block removed from the engine it is more convenient to use adaptation shown in fig. 5.7. In this case it is not required to establish a support under the "rassukharivayemy" valve and, besides, adaptation fixes a spring in the compressed situation that considerably facilitates removal of crackers.

12. … remove crackers …	13. … top plates of springs and spring …

14. … lower plates of springs …	15. … and mechanisms of rotation of final valves, and then take valves from the directing plugs.

PREVENTION After long operation at the top end face of the valve the agnail of a griboobrazny form can be formed. Before taking out of the valve from the directing plug remove this agnail with a file. It is strictly forbidden to beat out the valve from the directing plug the hammer through a mandrel without removal of an agnail as at the same time the internal surface of the plug will be inevitably damaged.

16. Remove resinous deposits from the top surface of a head and from inlet channels. These deposits can be softened and washed away kerosene or diesel fuel.

17. Clean a deposit from combustion chambers and final channels. Remove a deposit with the round metal brush established in an electric drill cartridge.

USEFUL TIPS Previously soak a deposit kerosene. Be careful: avoid to inhale the dust which is formed when cleaning combustion chambers. For prevention of formation of dust periodically moisten a deposit with kerosene.

18. Clear the internal surfaces of the directing plugs of valves a thin cylindrical brush from the copper wire clamped in an electric drill cartridge.

19. Remove from a head prileganiye surface to the block of cylinders the burned remains of sealing laying.

PREVENTION It is forbidden to clear a privalochny surface of a head metal brushes or an emery cloth. Use a shovel from a firm tree or plastic, previously having softened the laying remains solvent.

20. After cleaning examine a block head not to allow its operation with damages of carving openings, cracks (especially between saddles of valves and in final channels), corrosion, inclusions of alien materials, sinks and fistulas.

PREVENTION It is forbidden to make cracks, sinks and fistulas. Replace a defective head.

21. Check by means of the metal ruler established on an edge and the probe planeness of a surface of a prileganiye of a head to the block in the longitudinal and cross directions, and also on diagonals. If the gap between an edge of a ruler and a surface of a head exceeds 0,1 mm, replace a head.

22. Clear of the remains of laying and a deposit of a surface of flanges of a head for installation of an inlet pipe and a final collector.

23. Check existence of deformations of flanges for an inlet pipe and a final collector, replace the deformed head.

24. Repair the damaged carving openings a carving pro-race taps or installation of the repair plug (vvertysh).

25. Check density of installation of caps of a shirt of cooling. When weakening their landing restore it stamping.

26. Define wear of the directing plugs of valves, having measured the internal diameter of an opening of the plug, diameter of a core of the valve and having determined a gap by a difference of these sizes. The gap for inlet valves has to be 0,030–0,065 mm, for final – 0,050–0,085 mm.

27. If the gap is more than admissible, repair plugs expansion to the closest of three repair sizes with increase in diameter of an opening by 0,075 mm, 0,150 and 0,250 mm of rather nominal diameter. At the same time in them it is necessary to install valves of the corresponding repair size with providing a nominal gap in interface. Develop openings of plugs, using a set of development with the directing shaft. In order to avoid a vykrashivaniye of a surface of the plug a layer of the removed metal at each pass and giving of the tool have to be minimum.

PREVENTION The directing plugs are manufactured of steel by method of powder metallurgy, pressed in a head of the block and are not subject to replacement.

NOTES The directing plugs and valves of the repair sizes can be installed for technological reasons at manufacturer at assembly of the new engine. For simplification of selection of sets of repair details factory marking (tab. 5.2) applied in technological process of manufacturer, and service, used at service stations is applied on plugs and valves.

Fig. 5.8. Profile of saddles of valves: and – the inlet valve; – the final valve

28. Check a condition of saddles of valves. On working facets of saddles there should not be wear tracks, sinks, corrosion, etc. Saddles of valves can be replaced in a specialized workshop. Insignificant damages (small risks, scratches and so forth) can be removed grinding in of valves (see. "Grinding in of valves").	29. More major defects of saddles of valves eliminate with grinding, maintaining the sizes shown in fig. 5.8. Saddles are recommended to be ground in a specialized workshop as special tools and the equipment for this purpose are required.

30. Remove a deposit from valves and examine them. Deformation of a core of the valve and a crack on its plate are not allowed. In the presence of damages replace the valve. Check whether it is not too worn-out and whether the working facet is damaged. Grinding of a working facet of valves is allowed (in the repair shops having the corresponding equipment). After grinding the facet corner concerning the plane of a plate has to be 45 °30 '±5’, and thickness of a cylindrical part of a plate has to be not less than 0,5 mm. Insignificant risks and scratches on a facet can be removed grinding in of the valve to a saddle (see. "Grinding in of valves").

    

PREVENTION In order that on cores of valves risks were not formed, do not clear them wire brushes and metal scrapers.

31. Check concentricity of an arrangement of a plate of the valve and a saddle: apply on a valve head facet a paint coat (for example, the Berlin azure), insert it into the directing plug and, having slightly pressed to a saddle, turn. In the wake of paint on a facet of a saddle it is possible to judge concentricity of an arrangement of the valve and a saddle.

Fig. 5.9. Zones of wear of the valve: 1 – zone of the smallest wear of a core; 2 – core end face; 3 – a pro-point under crackers; 4 – zones of the greatest wear of a core; 5 – working facet; 6 – plate edge

32. Check wear of a core of the valve in the places shown in fig. 5.9. Nominal diameter of cores of all valves of 7,935-7,950 mm.

33. Check a state the protocheck 3 (see fig. 5.9) a valve core under crackers. At detection of traces of a vykrashivaniye of edges the protocheck and wear of a cylindrical part replace the valve.

34. Replace oil scraper caps irrespective of their state.

35. Examine springs of valves. Cracks and decrease in elasticity of springs are not allowed. At an opportunity determine elasticity of springs by the developed effort. According to technical requirements it has to make 625–650 N with a length of spring of 21,5 mm and 275-290 N with a length of 31,5 mm. And springs with cracks replace the bent springs (deformation in a free state more than 1,6 mm).

36. Check a condition of basic plates of springs. Replace plates with considerable wear of basic flutes under springs.

37. Always replace laying of an inlet pipe, a final collector and a head of the block of cylinders new, as removed, even externally not damaged laying can be strongly pressed out and will not provide tightness of consolidations.