Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1917-07-14
Unusual Noises Indicate
Faults In The Automobile
Even SFqhest Symptoms of Mechanical Trouble Should Be
Noted and the Causes Found and Emnated Tells
How You Can Discover Faults in Your Ca-Hammond Says
to Guard Against Carbon-ReaSons Why Things 90 wrong

pie. for cylinders mus be rebored or
ground and your engine then fitted
with properly designed oversize pls-
tons
The force Of the explosion is trans
mitted through the piston and wrist
pin to the connecting rod and con-
s!deration of the upper connecting rod
bearing introduces that common COM
plant, a bearing knock. This will
occur when the bearing has become
loose through wear, and usually re-
suits in a sound which is sharper than
the dull pound Of loose crankshaft
bearings.
Return now to the connecting rod
and notice that, with respect 70 the
wrist pin, 1t does no rotate, but os-
cillates like a pendulum. 1t occurs to
you that, this being the case, the bear
ing should receive but little wear and
demand but little attention. Let US
take an example. When you use a
piece Of sandpaper you do not push it
across the surface in one direction;
you rub 1t back and forth, because
when used in this way abrasion is
more rapid. The rubbing surfaces Of
the bearing, no matter how smooth
they may appear to the eye, are mi
croscopically rough, rough enough to
cause wear, and abrasion is more
rapid because of the alternate rubbing
first in one direction and then in the
other. Also bear in mind that this
bearing 10 located In q comparatively
hot part of the engine, Is less readily
fabricated than the bearings on the
crankshaft and hence should not be
neglected when the motor is overhaul
ed.
cranItshaft Trouble
Through the larger bearing at the
lower end Of the connecting rod, pis-
ton thrust Is transferred to the crank.
shaft and rotation begins. 1t Is in
these bearings and the main bearings
which support the crankshaft that
humping becomes most apparent and
most serious. Considering the con-
tinual shock to which these bearings
are subjected, they are long lived.
but little looseness rapidly develops
more play by providing an opportunity
for hammering to take place on the
soft metal Of the bearing surface. At
the first indication of trouble, tighten
the bearings, or, better still, have the
bearings frightened, for bearing adjust
ment is an art well worth the atten-
tfon Of a skilled mechanic.
Noise which you are inclined to at.
tribute to loose bearings may be
caused by their being out of align
ment, or, II you have failed to heed
the warning given by pounding bear
ings, your crankshaft may be sprung
and no amount of bearings adjustment
win stop the noise. There is but one
alternative, and you must face the de-
lay and expenses consequent to re-
grinding the crankshaft and scraping
q complete set of bearings to fit II.
At the front end Of the crankshaft
we find the timing gears, usually driv-
ing, through suitable reduction, the
carnshaft, one side Of the motor, and
the pump and generative shaft on the
other. Noisy gears are due to improp-
er design, faulty cutting or wear, which
gives rise to sufficient play to cause a
sharp impact as each tooth engages
with that Of its rating gear. The old
straight tooth spur. gear has been al
most universally superseded by gears
with teeth set at an angle and so de,
signed that they slide gradually and
smoothly into contact In this way
the manufacturer has ATTEMPTED to
eliminate gear noise, for once 1t devel-
ops, your only remedy is gear replace
ment In most modern engines lubri.
cation is automatic, oil being supplied
from the crankcase, but many motors
are In use In which the gears are sep
arately encased. II your timing gears
require separate fabrication, see that
the lubricant is not too heavy to flow
freely when at operating temperature,
for the rapidly revolving gear soon
cuts track through solid grease and
the faces Of the teeth receive little
fabrication. A second don't applies
to the use of so-called tnoiseless'
grease, which is merely q lubricant
containing q filler of ground cork or
other material for deadening the
noise. The effect is about the Same
as that which You would obtain by add
ing few handfuls Of saWdust to the
oil In the gear case, and such q pre-
tentative is not likely to appeal to any
owner who values his car.
SquesISy Valve Stems
Silent chain drive to magnetic OF
camshaft presents no particularly diff.
ferent feature so far as care is con.