6A-1
ENGINE
COOLING
AND
LUBRICATION
CONTENTS
OF
THIS
SECTION
SUBJECT
PAGE
Cooling
System Description
.........
6A-1
Radiator
and Cap 6A-1
Water
Pump. 6A-2
Fan
6A-2
Service
Operations 6A-2
Thermostat
6A-3
SUBJECT
PAGE
Water
Pump . 6A-3
Radiator.
6
A-3
Oil
Filter
. 6A-5
Drive
Belt
Chart
6A-7
Torque
Specifications 6A-8
Service
Specifications 6A-8
GENERAL
DESCRIPTION
ENGINE
COOLING
SYSTEM
The
cooling system consists of the radiator, cap,
radiator
hoses,
water pump, cooling fan, pellet-type
thermostat and suitable
passages
for water
circula-
tion through the
engine.
RADIATOR—ALL MODELS
A
cross-flow radiator is used on all 1968 Pontiacs
instead of the conventional down-flow type
0
The
cross-flow radiator differs in the fact that water
flows horizontally and the tanks are on the
left
and
right
side of the core instead of
above
and
below
the
core.
The
cross-flow radiator offers improved cooling
capabilities while making possible a lower front end
silhouette due to its reduced height. The low, wide
shape of the cross-flow radiator matches the grille
opening more efficiently, providing greater radiator
exposure and more
effective
cooling surface.
Radiators
used with automatic transmission have
oil
coolers built into the right tank with inlet and
outlet
fittings for circulation of transmission fluid.
The
Pontiac radiator used with automatic transmis-
sion is equipped with heavy duty oil cooler when
used on police
cars,
trailer options, etc., and as
optional equipment where extreme cooling conditions
must be met.
The
radiator used with the synchromesh trans-
mission is a cross-flow without oil cooler.
Cars
equipped with air conditioning and performance op-
tions
use a radiator which has more cooling capacity
for greater cooling demands.
A
drain
cock is located at inside lower
left
corner
of radiator.
RADIATOR
CAP
A
pressure-vent cap is used on the radiator to
allow a build-up of 15 psi of pressure in the cooling
system.
This
pressure raises the boiling point of
coolant to approximately
258°F.
at sea level.
CA
UTION:
As long as there is
pressure
in the
cooling
system, the temperature can be consider-
ably higher than the
boiling
temperature of the
solution
in radiator without causing the solution to
boil.
Removal of the radiator cap while engine is
hot and
pressure
is high
will
cause the solution to
boil
instantaneously and possibly with explosive
force,
spewing the solution over engine, fenders,
and
person removing cap. If the solution contains
inflammable anti-freeze, such as alcohol, there is
also
the possibility of causing a
serious
fire.
When
removing
filler
cap, rotate cap toward left very
slowly;
if
hissing
of vapor is encountered, tighten
cap
immediately and wait for system to
cool
suf-
ficiently
to allow removal of cap. After
pressure
in
system has been relieved, turn cap more
forcibly
to left and remove.
Turn
cap all the way
to right when installing. It should not be necessary
to check coolant
level
unless temperature gauge
shows
over-heating, and then not until engine is
stopped
and allowed to
cool
to normal.
The
pressure type radiator filler cap contains a
blow off or pressure valve and a vacuum or atmos-
pheric
valve. The pressure valve is held against its
seat by a spring of pre-determined strength which
protects the radiator by relieving the pressure if an
extreme case of internal pressure should
exceed
that
for which the cooling system is designed. The vacu-
um
valve is held against its seat by a light spring
which
permits opening of the valve to relieve vacuum
created in the system when it
cools
off and which
otherwise might cause the radiator to collapse.
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