Pueblo chieftain., 1921-09-04
LEAkY SPARK PLUGS
MIKE nm Engine Idle .itaEEedly y

They Make nm Engine Idle "aaggediy'
Leakage may occur either between
the cylinder block and the shell of the
plug or between the insulating porce-
lain core and the shell, in the case OF
separable plugs Leakage at the for
mer point is generally caused ly the
plug not being screwed in firmly
enough, by the failure of the copper
gasket used under the plug to afford
"A tight joint or by the sasket having
been accidentally omitted entirely.
These gaskets flatten out in use ana
lose their yielding nature, making
their renewal rather frequently neces-
sary and coarse grit on the gasket
will often make it leak. Leakage
thru the plug itself is usually caused
by u worn out gasket between the core
and the shell or by the packing nut
that congresses the jacket, not being
tight enough. When the external part
of the porcelain is found covered with
OIL it is evidence that the plug is not
tight and if OIL squirted around the
base of the plug shell is seen to bubble
when the engine is running, consider
able leakage is occurring. Such de-
fects. if bad. cause disagreeabie
chipping" sounds, and create air
leaks. which make the cylinders af-
fected misfire at low throttle. thus pre-
ventilating regular idlinG and smooth
running at very low speeds. Priminr
cocks with faulty valves and valve
kets arc Objectionable in ths same
way.
] Renewing Cnm-shaft Bearings
d l. McA Writes: The cam-shaft of
this be corrected? How can the cam
shaft be removed? Is this job that
can do myself?
Answer: This cam-shaft runs in
three bronze bushings held in brackets
cast in the upper crankcase section
and ~ these hearings loose.
the bushings will have to be driven
out and replaced with new ones OBJ
tanned from the factory, which Will
probably have TO be reamed to fit the
shaft. To remove the shaft the radia-
tor and timing gear cover are removed
and the thrust collar on the shaft. at
the center bearing, loosened, when the
shaft can be drawn out forward. after
the valves are removed 10 free the
push rods. Unless the engine is pNac-
tically disassembled, We fear that it
would be impossible to drive out the
cam shaft bushings and fit the new
ones This job is one which would he
difficult to perform without a good
shop equipment and considerable me-
chantcal skill and. as It involves tear
ing down the engine almost complete
ly. IT should be deferred. II possible,
until a general overhauling is under
taken.
II II. r. Writes: When l first start
out with my car and the engine Is
cool II runs without knocking. but
when II becomes helted-and 1t seems
to heat rather too much-a knock
commences. The engine is all right
mechanically and have had the cool
ing system cleaned out and carbon
removed. What kind OF a knock Is
this?
Arswcr: We do no, know. but ven
ture the following suggestions: One
kind OF knock that occurs only when
an engine is hot Is that due to !mper-
feet lubrication resulting from the use
Of an oil that becomes excessively
thin. under high temperature. You
better be sure that YOUR oil maintains
sufficient body, even when the en-
Einc Is hot. Knocks from irregular
combustion are more noticeable when
charges are hot and when rich mix
turc Il used. Possibly. thinning your
mixture would he beneficial. II your
circulating water gets so hot as to boil
away rather rapidly. overhcatinE Isl
very likely occurring. but II It does
not boil. We doubt n the system Ia any
too hot. OF course. II there L. any
thing about the cylinders capable OF
causing prciEnition. " wiz show up
especially when the engine Is heated.
Arc your spark plugs right for this en-
rineF
ono OF the most serious shortcom-
inrs Of inferior cylinder oil Is It's
tendency to thin unduly. when heated
to tho working temperature of tho en-
Einc. Tho function OF oil is to form a
thin cushion between pistons and cylin-
dor walls and between shafts and their