adjust the valves periodically. The engine lubrica-
tion system supplies a flow of oil to the lifters at all
times. These hydraulic lifters operate at zero clear-
ance and compensate for changes in engine tem-
perature, adapt automatically for minor wear at
various points, and thus provide ideal valve timing.
The first indication of a faulty hydraulic valve
lifter is a clicking noise. In one method for
locating a noisy valve lifter, you use a piece of
garden hose. Place one end of the hose near the
end of each intake and exhaust valve and the other
end of the hose to your ear. In this way you can
localize the sound, making it easy to determine
which lifter is at fault. Another method is to place
a finger on the face of the valve spring retainer.
If the lifter is not functioning properly, a distinct
shock will be felt when the valve returns to its seat.
Usually, where noise exists in one or more of
the valve lifters, you should remove all lifter units,
clean them in a solvent, reassemble them, and
reinstall them in the engine. If dirt, carbon, or
the like, is found in one unit, it more than likely
is present in all of them; and it will be only a
matter of time before the rest of the lifter units
will give trouble.
For such services as valve or valve seat
grinding, valve seat insert replacement, and valve
guide cleaning or replacement, you need to
remove the cylinder head and valves from the
engine. Avoid interchanging valves; each valve
must be replaced in the valve port from which it
was removed. A valve rack in which the valves
may be placed in their proper orderalong with
their valve springs, retainers, and locksis
Different tools and
procedures for removal are used for different
engines. Check the manufacturers maintenance
manual for your particular engine.
The first step in servicing valves after they have
been removed from the engine is to rid them of
carbon. The best method for doing this is cleaning
them with a wire buffing wheel or brush.
When using the wire buffing wheel,
always wear goggles to protect your eyes
from wire or carbon that may fly off the
After the cleaning process, inspect each valve
to determine whether it can be serviced and reused
or must be replaced. The valve should be checked
with a run-out gauge for eccentricity and inspected
for worn valve stem and badly cracked, burned,
or pitted valve face. Minor pits, burns, or
irregularities in the valve face may be removed
To grind valves, clamp the valve stem in the
chuck of the valve-refacing machine so that the
face of the valve will contact the grinding wheel.
(See fig. 3-16.) Set the chuck at the proper angle
to give the correct angle to the setting face. This
angle must just match the valve seat angle. It is
becoming common, however, in some engines to
reface the valves at a slightly flatter angle than
the seat, usually 1/4° to 1°, to provide what is
known as an interference angle. This angle
provides greater pressure at the upper edge of the
valve seat, which aids in cutting through any
deposits that form and provides for better sealing.
Some engines use the interference angle on the
exhaust valve only, and others use it on both the
intake and exhaust valves.
manufacturers manual for the recommended
angle for both valve and valve seat.
Because of the different angles between
the valve and the valve seat, do NOT use
grinding compound to finish the surface.
At the start of the grinding operation, make
the first cut a light one. If metal is removed from
only one-third or one-half of the valve face, check
to make sure you have cleaned the valve stem and
grinder chuck thoroughly and centered the valve
Figure 3-16.Valve-refacing machine.