Pontiac firebird 1968 - Page 299

6 A-2
1968 PONTIAC SI RVICE MANUAL
WATER PUMPS CYLINDER
The centrifugal-type water pump, divider, Internal
housing and aluminum timing chain cover are all
part of the coolant circulation system.
The water pump impeller turns on a steel shaft
mounted on a double row of permanently lubricated,
sealed ball bearings. A bellows-type seal is seated
in the water pump body between bearing and impeller.
The seal surface is a phenolic washer which is held
by the spring-loaded bellows against a ceramic seal
seat which seals the pump shaft via a rubber boot.
The inlet side of the pump is connected to the
lower radiator tank by means of a hose. A water
leg in 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 connection.
SERVICE OPERATIONS
CHECKING AND FILLING COOLING SYSTEM
The Pontiac and Tempest cooling system requires
little care except for maintaining an adequate coolant
level. If GM glycol-type inhibited engine coolant is
used, it is not necessary to drain the coolant for
summer driving because this coolant has been es-
pecially formulated to last 24 months in the cooling
system. After service for 24 months, drain the sys-
tem, flush it with water, and refill with an inhibited
year-round coolant meeting the GM 1899M specifica-
tion. If other than Pontiac-approved inhibited glycol-
type antifreeze solution is used, the cooling system
should be drained, flushed and refilled for the sum-
mer months. When water is used, a good corrosion
inhibitor must be added to the system. Failure to use
an inhibited coolant may result in severe corrosion
damage to the cooling system components.
WATER PUMP-6 CYLINDER
The centrifugal-type water pump contains an im-
peller which turns on a steel shaft which rotates in
a ball bearing. A bellows- type seal is seated in the
water pump body between the bearing and impeller.
The inlet side of the pump is connected to the
right radiator tank by a hose. Above the pump inlet
from the radiator is the inlet from the heater core.
Located beneath the coolant outlet at the side of the
rocker arm cover is the recirculation hose which
connects to the inlet side of the pump.
FAN
The fan is used to increase the air flow through the
radiator at all speeds.
All cars except G.T.O., 428 H.O. and air condi-
tioned cars have a fan which has four blades which
are unevenly spaced and have curled tips to provide
minimum noise. A seven bladed fan is used on cars
with air conditioners. A variable pitch fan is used on
A/C equipped 6-cylinder cars and on G.T.O. and 428
H.O. cars without air conditioning.
A fan shroud is used to prevent recirculation of
air around the fan on most air conditioned cars and
a number of non-air conditioned cars.
The thermostatically controlled fan is used on
most V-8's with A/C, along with a seven bladed fan.
The fan clutch is also available as an option on V-8
engines, except the Ram-Air engine.
FLUSHING COOLING SYSTEM
1. Drain radiator and block by opening drain plug
on radiator left tank and removing plug on left side
of 6 cylinder engine block and on both sides of 8
cylinder engine block.
2. After system is empty, with drains open, run
water into radiator. Engine should be running and
occasionally accelerated to aid in circulating water
and dislodge rust and scale.
CA UTION: Do not introduce cold water into a hot
engine or block may be cracked. Allow engine to
cool, then add water with engine running.
3. Where there is difficulty in getting water to
run clear or there is an excessive amount of rust
and scale, the cooling system should be cleaned with
a cleanser (reputable source) supplied for that pur-
pose. If force-flushing equipment is used it should
be used on the radiator only (engine to radiator inlet
and outlet hoses removed) as any reverse flushing
of the block with the water pump in place may cause
the water pump seal to leak, if flushing pressure is
excessive.
PREPARING COOLING SYSTEM FOR COOLANT
The cooling system should be properly prepared
for the addition of coolant every two years.
To properly prepare cooling system:
1. Bring engine up to operating temperature.
2. Flush out cooling system as indicated
previously.