Replacement
1. On SOHC models, remove the rocker arms and rocker pins. On DOHC models, remove the camshafts. Remove the valve clearance adjusters from the damaged valves.
2. Remove the spark plugs from the failed valve cylinders. If you are replacing all valve stem gaskets, remove all spark plugs.
3. Set the piston of the desired cylinder to TDC.
4. Screw the adapter into the spark plug hole and connect the air compressor hose to it.
5. Pump compressed air into the cylinder, the valves will be held in place by air pressure.
6. Turn the crankshaft clockwise until you feel a slight resistance.
7. Compress the valve springs with a special compressor. Remove the cone bushings.
8. Remove the spring plate and valve spring. Remove the valve stem seals.
9. Release the air pressure in the cylinder.
10. Inspect the valve spring for cracks or damage, and measure the free length of the spring. Inspect the valve stem.
11. Check if the valve stem is sticking and measure the clearance between the stem and guide bushing. If necessary, the cylinder head will need to be removed to repair the valves and guides.
12. Increase air pressure to close valves.
13. Lubricate the valve stem with oil and install a new seal.
14. Install the spring and spring plate. Compress the spring and install the cone bushing.
15. Install remaining parts and check engine operation.