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PART 1-1
-ENGINE
1-11
ENGINE TROUBLE DIAGNOSIS GUIDE
(Continued)
ENGINE OVERHEATS
(Continued)
Thermostat defective.
Thermostat
improperly
installed.
Cooling
system
passages
blocked.
Water pump inoperative.
Faulty
fan drive.
IGNITION SYSTEM
Incorrect ignition
timing.
LOSS OF COOLANT
ENGINE
FAILS TO REACH
NORMAL OPERATING
TEMPERATURE
NOISY HYDRAULIC
VALVE LIFTER
COOLING SYSTEM
Leaking
radiator.
Loose
or
damaged hose
connec
tions.
Water pump leaking.
Radiator cap defective.
Overheating.
ENGINE
Cylinder head
gasket
defective.
Intake
manifold
to
cylinder
head
gasket
defective.
Cylinder head
or
intake
manifold
bolts
not
properly
torqued.
Cylinder block
core
plugs
leak
ing.
Temperature
sending
unit
leak
ing.
Cracked
cylinder
head
or
block,
or
warped
cylinder
head
or
block
gasket surface.
TEMPERATURE SENDING
UNIT AND GAUGE
Unit
or
gauge
defective (not in
dicating
correct
temperature)
or con
stant voltage regulator
defective.
COOLING SYSTEM
Thermostat inoperative
or
of
in
correct
heat
range.
A
noisy
valve
lifter
can
be located
by
operating
the
engine
at
idle
speed
and
placing
a
finger
on
the
face
of
the
valve
spring
retainer.
If
the
lifter is
not
functioning
prop
erly,
a
shock
will
be felt
when
the
valve
seats.
Another
method
of
identifying
a
noisy lifter
is
by
the
use of a piece
of
hose. With
the
engine
operating
at
idle
speed,
place one
end
of
the
hose
near
the
end
of
the
valve stem
and
the
other
end
to
the
ear
and
listen for
a
metallic
noise.
Repeat
this
procedure
on
each
intake
and
exhaust
valve
until
the
noisy
lift-
er(s)
has been located.
The
most
common
causes
of
hy
draulic
valve
lifter
troubles
are
dirt,
gum, varnish,
carbon
deposits,
and
air
bubbles.
Dirt
in
the
lifter assembly
can
prevent
the
disc
valve
from
seating,
or
it may
become
lodged between
the
plunger
and
body
surfaces.
In
either
case,
the
lifter becomes
inop
erative
due
to
failure
to
"pump-up,"
or
because
the
internal
parts
are
no
longer
free
to
function
properly.
When dirt is
found
to
be
respon
sible
for lifter
malfunction,
remove
the
lifter assembly
and
thoroughly
clean
it.
Recommended
engine
oil
and
filter
change
intervals
should
be
followed
to
minimize
lifter
prob
lems
caused
by
dirt.
Deposits
of
gum
and
varnish
cause
similar
conditions
to
exist
which
may
result
in lifter
malfunc
tion.
If
these
conditions
are
found
to
be
present,
the
lifter
should
be
disassembled
and
cleaned
in
solvent
to
remove all
traces
of
deposits.
Air bubbles in
the
lubricating
oil,
caused
by
an
excessively
high
or
low
oil
level,
may
likewise
cause
lifter
malfunction.
A
damaged
oil
pick-up
tube
may
allow
air
to
be
drawn into
the
lubricating
system.
To
check
for
the
presence
of
air,
remove
a
valve rocker arm cover and
note
the
condition
of
the
oil as
it flows
from
the
valve rocker arm shaft as
sembly.
Perform
corrective
action as
required
to
remove
air
from
the
lubri
cating
oil.
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