The Washington herald., 1921-09-18

results. Furthermore, 1t is possible
to get this same condition by the
use of an incorrect grade of oil. II
too thin an oil is used the lubricant
will force it's way past the rings
into the combustion chamber. In
many cases the car owner uses an
oil of too thin a body and when
rapid carbonization takes place he
suspects the pistons, the rings and
almost everything else except the
true cause of the trouble. Every
car manufacturer recommends
certain grade of oil to be used in
his engine, and his advice should
be rigidly adhered to by the car
owner. In case there is any ques-
tion in the matter the advice OF the
service station should be asked. The
commonly recommended lubricant is
a medium body oil. but this is not
universal, so the car owner should
make absolutely sure of his ground
in this vitality important matter.
1t is also true that a heavier
grade of oil is usually needed in
summer than in cold weather. Heat
tends to reduce the body of oil,
thinning out the viscosity just as II
does with molasses. Very often,
too, a heavier oil is needed in old
cars than the one which served very
we'll when the vehicle was young.
The reason for this is that the parts
of the mechanism have worn, the
clearances are greater and a heavier
bodied oil is needed to stop the
gaps.
Suspicion of Piston
that the proper amount and the
proper quality of oil are being used
and still sooted plugs and general
carbonization betray the presence of
oil leaking the piston rings and the
piston itself are open to suspicion.
In many cases failure OF the pis-
ton rings to prevent the oil from
leaking into the combustion cham
Der is due to the fact that they are
not properly fitted in the cylinders.
II a ring is not accurately placed in
it's grooves, or IL II sticks in its
groove instead of being sprung out
against the cylinder wall, of course
oil can force its way into the upper
part of the cylinder. 1t often hap
pens that foul oil. in which there is
a considerable amount OF foreign
matter, forces its way into the ring
grooves. thereby preventing the
ring from resting properly in It's
groove.
Fitting piston rings means more
than merely placing the rings IN
their grooves. The rings must mt the
grooves so that there is perhaps
.0O1 of an inch up and down clear
ance, or just enough to prevent
leakage, and still not cause the
ring to stick. The ring should be
Tapped in size and ring fitting
should be done by experienced
hands.
value of Special Rings.
There has been a tendency in re-
cent years when engine lubrlcatinE
troubles occur to fit some special
type Of piston ring and believe that
settles the matter. Many OF the
special rings have real value, but
they c,ust be accurately fitted, Just
the same as an ordinary diagonally
split ring.
Now beyond the rings as possible
sources of fabrication trouble there
is the cylinder itself. 1t frequently
happens that after car has been
run for a long time one or more
cylinders wear out of true. Obvious
ly in this case the ring. which Is
round, does not fit tight against the
cylinder wall. The result is now
of oil into the combustion chamber.
The only cure for this condition Is
to have the cylinder rebored. There
are firms specializing in this in
every city. Even IL only
one cylinder is out of round, the
entire set should be rebored and a
new set of pistons installed.
In some cases it Is possible to
cure a chronic case of oil pumping
by drilling the skirt of the piston
with one-sixteenth inch holes,
spaced at equal distances under the
lowest groove. This, with perhaps
the addition of a scraper ring in
the skirt will often work won
ders.
Finally a scored cylinder will in
luce oil pumping, since the trenches
ID the cylinder wall allow the oil to |
past the rings. In this case |
the cylinder will have to be ope--
ated upon by some specialist in this |