Valve springs, retainers and seals — replacement
Note: Broken valve springs and defective valve stem seals can be replaced without removing the cylinder head. Two special tools and a compressed air source are normally required to perform this operation, so read through this section carefully and rent or buy the tools before beginning the job.
1. Remove the spark plugs (see Tune-up and routine maintenance).
2. Remove the valve covers (see Valve covers — removal and installation).
3. Rotate the crankshaft until the number one piston is at Top Dead Center on the compression stroke (see Top Dead Center (TDC) for number one piston — locating).
4. Remove the rocker arms for the number one piston.
5. Thread an adapter into the spark plug hole and connect an air hose from a compressed air source to it (see illustration). Most auto parts stores can supply the air hose adapter.
6.5 This is what the air hose adapter that fits into the spark plug hole looks like — they’re commonly available from auto
parts stores
Note: Many cylinders compression gauges utilize a screw-in fitting that may work with your air hose quick-disconnect fitting. If a cylinder compression gauge fitting is used, it will be necessary to remove the Schrader valve from the end of the fitting before using it in this procedure.
6. Apply compressed air to the cylinder. The valves should be held in place by the air pressure.
Warning: If the cylinder isn’t exactly at TDC, air pressure may force the piston down, causing the engine to quickly rotate. DO NOT leave a wrench on the crankshaft balancer bolt or you may be injured by the tool.
7. Stuff shop rags into the cylinder head holes around the valves to prevent parts and tools from falling into the engine.
8. Using a socket and a hammer, gently tap on the top of each valve spring retainer several times (this will break the seal between the valve keeper and the spring retainer and allow the keeper to separate from the valve spring retainer as the valve spring is compressed), then use a valve-spring compressor to compress the spring. Remove the keepers with small needle-nose pliers or a magnet (see illustration).
6.8 Once the spring is depressed, the keepers can be removed with a small magnet or needle-nose pliers (a magnet is preferred to prevent dropping the keepers
Note: Several different types of tools are available for compressing the valve springs with the head in place. One type grips the lower spring coils and presses on the retainer as the knob is turned, while the lever-type shown here utilizes the rocker arm bolt for leverage. Both types work very well, although the lever type is usually less expensive.
9. Remove the valve spring and retainer.
Note: If air pressure fails to retain the valve in the closed position during this operation, the valve face or seat may be damaged. If so, the cylinder head will have to be removed for repair.
10. Remove the old valve stem seals, noting differences between the intake and exhaust seals (see illustration).
6.10 Use a pair of needle-nose pliers to remove the valve seals
11. Wrap a rubber band or tape around the top of the valve stem so the valve won’t fall into the combustion chamber, then release the air pressure.
12. Inspect the valve stem for damage. Rotate the valve in the guide and check the end for eccentric movement, which would indicate that the valve is bent.
13. Move the valve up-and-down in the guide and make sure it does not bind. If the valve stem binds, either the valve is bent or the guide is damaged. In either case, the head will have to be removed for repair.
14. Reapply air pressure to the cylinder to retain the valve in the closed position, then remove the tape or rubber band from the valve stem.
15. Install a new valve stem seal over the valve stem and press it down over the valve guide to the specified depth. Don’t force the valve seal against the top of the guide.
16. Install the spring and retainer in position over the valve.
17. Compress the valve spring assembly only enough to install the keepers in the valve stem.
18. Position the keepers in the valve stem groove. Apply a small dab of grease to the inside of each keeper to hold it in place if necessary (see illustration). Remove the pressure from the spring tool and make sure the keepers are seated.
6.18 Apply a small dab of grease to each keeper as shown here before installation it’ll hold them in place on the valve stem as the spring is released
19. Disconnect the air hose and remove the adapter from the spark plug hole.
20. Repeat the above procedure on the remaining cylinders, following the firing order sequence (see this Chapter’s Specifications). Bring each piston to Top Dead Center on the compression stroke before applying air pressure (see Top Dead Center (TDC) for number one piston — locating).
21. Reinstall the rocker arm assemblies and the valve covers (see Sections Valve covers — removal and installation and Rocker arms and pushrods — removal, inspection and installation).
22. Start the engine, then check for oil leaks and unusual sounds coming from the valve cover area. Allow the engine to idle for at least five minutes before revving the engine.