New-York tribune., 1918-01-20
By William II. Stewart, .Tr.

"Out of sight, out of mind" applies.
too often to the unseen parts of the
engine or car. This refers particularly
to the valves, as they are subject to
many troubles which come on grad
ually, with consequent loss of power.
The average driver knows that the
valves should be ground at some time
or other, but, since they are difficult
to reach, he neglects them until tho
loss of power becomes SO serious that
he decides something must be done.
The most frequent cause of lost
power is leaky valves. Carbon is the
most frequent offender. Other causes
are pitting and burning, warping, bent
stem, broken valve or spring and push
rod adjustment set too close. The re-
suit is leakage of gas past one or
moro valves.
70 locate the cylinder or cylinders
at fault, the engine must be cranked
by hand. Run the engine ten minutes
CT moro to warm thoroughly and then
test as follows: Open all compression
cocks except the one of the cylinder to
be tested. Crank the engine and note
the resistance due to compression
Open that compression cock and close
the one on the next cylinder to be
tested. Crank and compare the resist
ance. Continue in the same way with
the remaining cylinders. Having found
one or more cylinders to be weak, do
not Immediately condemn the valves
There are many places through which
compression may escape. Run the en-
gine under its own power and inject
Gil around the spark plugs, relief
valves, valve caps and cylinder head, if
it is removable. If air bubbles through
the oil the trouble is there and not in
the valves at all.
There May Be Leakage
The remedy TO be applied depends
on the trouble. If spark plug or
compression cock is at fault it must
oe screwed more firmly into the cyl
inder- If this does not stop leakage, a
mixture OF graphite and shellac must
be rubbed into the threads. The spark
same remedy may be applied for
leaky valve cap. Be sure to get a
gasket of the proper size Where the
cylinder head is removable there is
always a possibility Of leakage around
the gasAet Tighten the bolts near the
leak and test again. Such q gasket
should be shellacked when applied.
haying determined that there are no
leaks at the points mentioned, the
move the valve caps and the plates
covering the valve stems. If the CYL
lnder head is removable it must be
taken off. A skilled workman can re-
move the valves without special tool
called valve spring litter, but the be-
glnner should have one. Be careful
not to bend the stand of the valves.
FIRST remove the exhaust valves from
the cylinders with weak compression
and scrape the carbon from top and
stem, using a knife Do not touch
anything metallic 10 the valve faca
the pant that touches the valve scat
"hen IN position in the cylinder).
IL the face is badly sooted or pitted,
ana SHOWS traces of burning or warn,
ing. it must be ground. Apply a thin
coating of grinding compound to face
OF valve and lower it into place. De-,
NOT drop 1t into place, as the emery
VIII spatter and some of it NAV be-
come embedded in the valve seat. Some
valves arc slotted for screwdriver
ana others require special tool that
comes with the car.
Grlnd back and forth, spinning the
tool between the palms of the hands.
10 not grind round and round. but
back and forth.
How to Grind Properly
1han
1t into a new position. Grind a short
time and lift and turn again, always
turning IN the same direction. At the
end OF a few minutes remove the valve
and wipe of the face to see how the
work is progressing. If any pits re
mann, or if Il bright line does not ex
TEND all the way around, the process OF
grinding must be continued. When
finished. all the emery must be re-
moved from the valve and valva soat