Note: Broken valve springs and worn valve stem seals can be replaced without removing the cylinder head. All you need is two special tools and a source of compressed air.
1. Remove the cylinder head cover (see Removal and installation the cylinder head cover).
2. Remove the spark plugs from the cylinders whose components need to be checked. If the valve stem seals need to be replaced, remove all the spark plugs.
3. Turn the crankshaft and bring the corresponding piston to the TDC position at the end of the compression stroke (see Bringing the piston of the first cylinder to the top dead center (TDC) position). When replacing valve stem seals, start with the first cylinder, then move from one to the next in the firing order (see Specifications).
4. Remove the rocker arm assembly with axles (see Removal, condition check and installation of rocker arm assembly).
5. Screw the adapter into the spark plug hole of the corresponding cylinder and connect a hose from a compressed air source to it.
Note: Special threaded nozzles with quick-connect fittings are available (see accompanying illustration) – ask in car service shops.
6. Supply air to the cylinder.
Caution! Under air pressure, the piston may move downwards, which will lead to sudden crankshaft rotation - do not leave the socket wrench used to bring the piston to the TDC position on the bolt screwed into the shaft journal.
7. The valves will be held in place by air pressure.
8. To prevent debris and other foreign objects from getting into the engine, plug all the holes in the block around the valves to be serviced with rags. Now, using a special tool, compress the spring of the valve to be serviced (see accompanying illustration). 9. Using needle-nose pliers or a magnet, remove the split lock crackers from the grooves on the valve stem (see illustration for paragraph 8).
10. Remove the spring plate, protective screen, and spring from the valve stem, then remove the oil deflector cap from the guide sleeve.
Note. If it is not possible to fix the valve in the closed position with compressed air, then there is a leak due to mechanical defects in the working chamfer of the plate or its seat. In this case, the cylinder head must be removed from the engine in order to perform the appropriate restoration repair.
11. Attach a rubber band to the upper end of the valve stem, or wrap it with tape to prevent the valve from falling into the combustion chamber, then shut off the air supply to the cylinder.
12. Check the valve stem for signs of wear or mechanical damage. Rotate the valve inside the guide bushing and estimate the amount of radial clearance of its end, which determines the degree of straightness of the stem (the bent valve needs to be replaced).
13. Move the valve up and down in the guide bushing, trying to identify jamming points, the presence of which indicates either deformation of the valve stem or damage to the bushing - in either case, the head must be removed in order to perform the necessary repairs.
14. Re-inject air into the cylinder to secure the valve. Remove the rubber band/tape from the rod.
15. Lubricate the valve stem with clean engine oil and install a new valve stem seal.
Note: The valve stem seal springs are color coded: white means the seal is designed for installation on the intake valve, black means the seal is designed for installation on the exhaust valve.
16. Place the valve spring on the valve stem (end with reduced pitch of threads to the head) with a plate.
17. Compress the spring using a special tool and carefully insert the split lock crackers into the mounting groove. To temporarily fix the crackers until the tool is released, lubricate them from the inside with thick grease (see accompanying illustration). 18. While observing the correct seating of the crackers in the groove, release the spring compression device.
19. Shut off the air supply to the cylinder and unscrew the adapter from the spark plug hole.
20. Install the rocker arm assembly (see Removal, condition check and installation of rocker arm assembly).
21. Install the cylinder head cover (see Removal and installation the cylinder head cover).
22. Screw the spark plugs back into place and connect them to them (in the required order) High voltage wires.
23. Start the engine and check it for signs of oil leaks and unusual noises from the valve train.