Advertisement
2-22
TROUBLE DIAGNOSIS
ENGINE
(44)
seat
with no shock
whatever
if valve lifter is
functioning
properly.
.
There are four
gen eral
types of hydraulic
valve lifter no
ise
that may be encountered as
follows:
(1)
Loud, Hard Rapping
Noise.
This may
be caused
by
an insufficient supply of oil to
valve
mechanism
due to low oil level in crank-
case,
defective oil
pump,
clogged oil passages
or dented oil pipes. If oil supply is satisfactory,
this condition is caused by the valve lifter plun-
ger sticking in bore of lifter bod
y
so that the
sp
r
ing'
cannot push plunger back to its
no~mal
working position. Clean or replace valve hfter
(par. 2-15).
(2)
Moderate
R
appin g
or
Clicking
Noise.
This can be caused
by
exc
essive
worn valve
stem guide,
eccentricit y
of val
ve
and seat, or
warped valve. See paragraph 2-17
.
It also can
be caused
by
excessive clearance of valve lifter
in crankcase, or by a worn or scored
cam.
Mod-
erate rapping or
clicking
also can be caused by
too rapid leakage of oil
between
lifter body and
plunger.
(3)
Intermittent
Clicking. This is the most
difficult condition to locate. It can be located
only by listening carefully or feeling with a
finger
on each valve
spring
cap or rocker arm
in su
ccession until
the click appears and is lo-
cated
either
by
hearing or
f
eeling.
This type
of click is almost always caused by a micro-
scopic piece of dirt wh
ich
keeps circulating
through the lifter and momentarily is caught
between the
check
valve ball and seat. In rare
cases
the ball itself may be out of r
ound
or
have a flat spot which upon contacting the seat
permits
leakage of oil.
Clean
or replace the
va lve lifter
(par. 2-15).
(4)
General Noise
Throughout the Valve
T
rain.
This
condition,
in almost all cases, will
be a definite indication of an insufficient
supply
of
oil to
valve
mechansim
caused by
low
oil level
in
crankca se,
defective oil
pump, clogged oil
passages
or dented
oil
pipes.
2
-1 1
HAR
D STARTING, IMPROPER
PERFORM AN CE,
EX CESSIVE
FUEL
OR OIL
CONSUMPTION
a
. Hard
Sta rting, Improper
Performance,
Excessive Fuel
Consum ption
These subjects are covered in Section 3-B.
See paragraph
3-5 for hard starting, paragraph
3-6
for improper engine performance, and para-
graph
3-7
for excessive fuel
consumption.
b.
Excessive Oil Consumption
If an
engine
is reported to be using an exces-
sive amount of oil, a thorough inspection should
be
made for external leaks and the conditions of
operation should be
carefully
considered before
assuming that the engine is
using
too much oil
as a result of an
internal condition
.
Place clean paper on
the floor under
engine
a
nd run the engine at
medium speed
until
the
oil
is
thoroughly
warmed up
, t
hen
stop the
engi ne
and check for oil
leaks and dripping
on the
paper. Inspect
both
sides and f
ront
and rear
ends of
engine for
wet
spo
t s.
Pay particular
attention to ro
cker a
r m cover, push rod cover,
and
lower crankcase gaskets.
All
external leaks
should be
corrected
and the results
noted
before
attempting
any
internal correction.
The conditions of operation have an impor-
tant bearing on oil cons umption.
The
following
points
shou ld be checked.
(1)
Improper
reading of
oil gauge
rod. An
erroneous
re
ading
will be
obtained
if
car
is not
level
,
gauge
r
od
is not
pu
shed dow
n
against
stop,
or insuffi cient
drain-back time
(1
m
inute)
is not
allowed
after
stopping
engine.
An over -
supply
of
oil
may
be ad
de d
if gauge rod mark-
ings
are not underst ood. The space between
arrows represents 2 quarts
and spac e between
adjacent
holes
r
epresents
one
quart.
(2)
Oil
too
light. The
use of oil of lower
viscosity
than specified f
or
prevailing
t
emper a-
tures will
contribute
t
o exc
essive
oil
consump-
tion.
(3) Cont
inuous high speed
dri
ving.
In any
automobile engine, in
crea sed
oil consumption
.per mile
may
be
expected at
speeds above 60
MPH.
(4) High speed
driving
f
ollowing slow
speed
town dr
iving.
When a car
is used
principally for
slow speed town
driving under conditions
where
considerable crankcase
dilution occurs,
a rapid
lowering
of oil level may occur when the car is
driven for some
distance
at
hi
gh
speed.
This is
because
the dilution
from
town
driving
is
re-
moved by the he
at
of t
he
high
speed driving.
This
is
a
normal
cond
ition
and should
not be
mistak en
f
or
excessive con
sumpt ion.
(5)
Vacuum
pump diaph ragm
leaking.
A
cracked
diaph ragm in the
vacuum pump can
cause ex
cessive oil
consumption by permitting
oil to be
drawn
f
r om the
crankcase through the
pump and int ake manifold into t
he
combustion
chambers. If
the
windshield wiper action is
sluggish
when
the eng ine is ac
celer at ed it indi-
Advertisement
