Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1917-07-14

The causes OF unnatural noises In
the automobile and the best ways OF
tracing and eliminating them are des-
cribed by Charles Hammond in the
following contribution.
= Let us approach the subject in this
way-Starting with the development
Of power in the cylinder, we will
follow its transmission TO the rear
wheels, considering those parts which
are subject to noise, It's cause and re-
medy. >.s.~
sThe explosion takes place in the
cylinder, and already We have en-
countsref fthe familiar complaint, a
knock In the engine A frequent
cause is explosion Of the mixture be-
fore the piston hes reached the top OF
/. its stroke Even when properly timed.
III force of this explosion acts on the
piston like the blow Of sledge ham
mer. Imagine, then, the shock to
which your bearings are subjected If
the explosion occurs at a time when
the piston Is rushing upward at high
velocity.
carbon accumulation may cause
premature ignition. When carbon
collects in the cylinder II is very like.
! " TO curl up in thin flakes on the
walls Of the combustion chamber
These flakes are soon heated to in
candescence, with the result that the
explosive mixture is ignited at the
wrong time. Carbon may be removed
mechanically by loosening 1t with one
Of the many liquid preparations and
then scraping, or by burning with
oxygen or oxy-acetylcne flame, but
when the burning method is employed
particularly the very hot oxy-acetylene
flame, reasonable care must be taken
against oyerheating the cylinder walls
and piston head.
Guard Against Carbon
'sOnce the carbon has been removed
DO what you can to prevent its forma'
ton. The burning process seems TO
leave surface on which carbon soon
FORMS again. Too rich mixture apd
too light an oil cause rapid carbon de
post, and that proportion Of II attri'
butable TO improper oiling can be
greatly lessened by the use Of the
heaviest oil which your lubricating
system permits.
"A more renaote cause of early igni.
ton 10 improper spark timing, for un'
less your timing gears have been re-
moved and wrongly replaced there, Is
little possibility of the manufacturer
Betting getting out of adjustment. To
kheck the timing insert q very thin
niece Of paper between the contact
points Of the interrupter. Now turn
me flywheel until the magnetic mark
(usuallyl indicated by the letter ND
corresponds with the fixed mark on
the frame. At this point the contacts
should inst release the paper, per.
hitting II to be withdrawn.
every often knock Ii caused by too
2tnn = mixture. and IN this case the
',nock wiz be more evident at slow
'tpeeds. A lean mixture Is fast burn
ING mixture, and explodes, exerting q
tuick, sharp blow on the piston head.
- rich mixture burns slower, the
.Iorce Of the explosion. IN comparison
.vith that of the lean mixture, Is more
traduaIly applied. and hence at slow
'0Epeeds the richer mixture Is more de-
..irable. The principle Is not unlike
mad which prompts you TO draw back
|our hands when catching q baseball
- as to lessen the impact. II the
aston Is travelling fast the blow is
|eadily absorbed, but II It is moving
Iowly the sharp explosionsof the lean
mixture Is sufficient to cause knock.
'If carburetor adjustment does not re-
nedy the difficulty look for dirt in the
'|nray nozzle, causing restriction OF the
/. low az gasoline, or for q leak In the
intake manifold, permitting excess OF
'Iir.
cause q Piston Slap
~Consider next the piston itself IN
''.ls relation to noise. Piston slap Is
xactly what the name implies. It ID
Y sound quite distinguishable from the
|ngine knock, and EXISTS because
There Is too much clearance between
HE piston and cylinder walls. When
.xplosion takes place the piston, using
tonnecting rod as an arm, tends TO
living about the crank shaft bearing
rs q centre and any excessive side
'blay Is quickly taken up, causing a
tharp blow or slap.
~ ~Often the cause can be traced to
loosely fitting piston rings, and II this
rs found 70 be the case you can also
blaze to their credit poor compression
Ind excessive carbonization. II. how.
,4ver, appreciable wear has occurred In
Abe cylinder, the remedy il less sim