Pontiac tempest 1968 Service Manual page 300

E N G I N E C O O L I N G A N D L U B R I C A T I O N
6A-3
3. Tighten all hose connections on radiator, en­
gine, heater and defroster. Replace any deteriorated
hose. Check to see that radiator hold-down bolts are
tightened properly.
4. F i l l system with water and operate engine,
checking for water leaks at radiator core, hose
connections, water pump seal and gaskets, heater
and defroster connections, and head to block joint.
5. Drain sufficient water to allow addition of prop­
er quantity of coolant.
Do not overfill. Coolant should be 1" below filler
neck opening with hot engine, 3" below filler neck
with cold engine for all models.
CAUTION: A pressure radiator cap is used to
provide the best cooling. When removing, rotate
cap to left very slowly. If hissing noise is heard,
stop and allow pressure to decrease before re­
moving cap completely.
To assure most effective heater performance, all
models are equipped with a 190°F. thermostat.
Therefore, the use of Pontiac-approved inhibited
glycol-type e n g i n e coolant g i v e s best heater
performance.
Non-glycol base coolant should not be used.
INHIBITORS
When only water is in the system, a cooling system
corrosion inhibitor must be used.
TESTING COOLANT
In using a hydrometer to determine the freezing
point of radiator solution, make sure correct hy­
drometer markings are read. Unless hydrometer is
provided with means for temperature correction,
test should be made at temperature at which hydrom­
eter is calibrated, for if the solution is warmer or
colder large errors may result (in some cases as
much as 30°F.) Most good hydrometers are equipped
with a thermometer and temperature correction
scale which allows an accurate test of freezing point
over a range of temperatures.
THERMOSTAT-REMOVE AND REPLACE
1. Drain radiator level to below thermostat and
remove water outlet assembly from rocker arm
cover (6 cyl.), intake manifold (8 cyl.).
2. Remove thermostat. Unless obviously defective,
test thermostat as follows before replacing with new
one:
a. Immerse unit and thermometer in container
of water over a heater. While heating water do not
rest either thermometer or thermostat on bottom
of container as this will cause them to be at higher
temperature than the water.
b. Agitate water to insure uniform temperature
of water, thermostat and thermometer.
A new thermostat (190°) valve should start to
open (
o
002
M
) at a temperature of 187°F. to 193°F.,
and should be fully open (3/8") or more at a tem­
perature not in excess of 222°F. A used thermostat
can be about 7°F. above or below this setting
(183° - 197°F.) without adverse effect and should not
be replaced. If thermostat does not operate at
specified temperatures, it should be replaced as
it cannot be adjusted.
3. Install thermostat with pellet or cartridge pro­
jecting down into water passage.
4. Using new gasket, install water outlet fitting.
Tighten bolts to 21 lb. ft. (6 cyl.), 28 lb. ft. (8 cyl.).
5. Refill radiator to approximately 3 , T below filler
neck for all models.
WATER PUMP—8 CYLINDER
NOTE: Wa ter pump is serviced only as an
assembly.
1. Drain radiator.
2. Loosen generator at adjusting strap and remove
fan belt from fan pulley.
3. Remove fan and pulley.
4. Remove water pump retaining bolts and remove
pump.
5. Install pump by reversing above steps. Tighten
water pump attaching bolts to 15 lb. ft. torque. Ad­
just belt for proper tension on chart at end of
this section.
WATER PUMP—6 CYLINDER
REMOVE
1. Drain cooling system and remove water inlet
and heater hoses.
2. Remove all fan and accessory drive belts.
3. Remove fan and pump pulley.
4. Remove upper front timing belt cover.