Pontiac FIREBIRD 1972 Service Manual page 627

ENGINE COOLING AND LUBRICATION 6A-7
WARM WATER
R U l U T D R
DRAIN
Fig. 6A-5 Cross-Flow Radiator
when installing. It should not be necessary to
check coolant level unless temperaturegauge or
light shows over-heating and then not until
engine is stopped and allowed to cool to nor-
mal.
The pressure-type radiator filler cap contains a blow off or
pressure valve and a vacuum or atmospheric valve (Fig.
6A-6). 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 vacuum 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.
WATER PUMP
8 CYLINDER (Except 307)
The centrifugal-type water pump, internal housing and
aluminum timing chain cover are all part of the coolant
circulation system (Fig. 6A-7).
The water pump impeller turns on a steel shaft mounted
on a double row of permanently lubricated, sealed ball
bearings (Pig. 6A-8). A bellows-type seal is seated in the
water pump body between the bearing and the impeller.
The seal surface is a phenolic washer which is held by the
spring-loaded bellows against a ceramic seal seat.
The inlet side of the pump is connected to the right radia-
tor tank by means of a hose. A water leg in the intake
manifold connects to the timing chain cover to provide
recirculation of water when the thermostat is closed. The
timing chain cover also has a heater water return connec-
tion.
The cooling systems water pump is of the centrifugal vane
impeller-type (Figs. 6A-9). The bearings are permanently
lubricated during manufacture and are sealed to prevent
the loss of lubricant or the entry of dirt and water. The
pump requires no care other than to make certain the air
vent at the top of the housing and the drain holes in the
bottom do not become plugged with dirt or grease.
Water pump components are not serviced separately;
therefore, in the event of water pump failure, it will be
necessary to replace the complete assembly.
6 CYLINDER
The centrifugal-type water pump contains an impeller
which turns on a steel shaft which rotates in a ball bearing
(Fig. 6A-10). A bellows-type seal is seated in the water
pump body between the bearing and the impeller.
The inlet side of the pump is connected to the right radia-
tor tank by a hose. The inlet from the heater core is located
above the pump inlet from the radiator. Located in the
coolant outlet at the front of the cylinder head is the outlet
to the heater core from beneath the thermostat.
FAN
R A D I A T O R COR
I I
Fig. 6A-6 Pressure-Type Radiator Cap
The engine fan is used to increase the air flow through the
radiator at all speeds (Fig. 6A-11).
CAUTION: If a fan blade is bent or damaged in
any way, no attempt should be made to repair
and reuse the damaged part. A bent or da-
maged fan assembly should always be replaced
'
with
a
new fan assembly.
It is essential that fan assemblies remain in proper balance
and proper balance cannot be assured once a fan assembly
has been bent or damaged. A fan assembly that is not in