Chevrolet Light Duty Truck 1973 Service Manual page 413

COMPONENTS
Water Pump
The cooling system water pump is of the centrifugal
vane impeller type. The impeller turns on a steel shaft
that rotates on a double row of permanently lubricated
ball bearings, which are sealed during manufacture to
prevent loss of lubricant and to prevent entry of dirt and
water.
The pump inlet is connected to the bottom of the
radiator by means of a rubber hose. Pump outlet is
separate from the pump and is located in the thermostat
housing which is connected to the top of the radiator by
a rubber hose.
Radiator
Radiators are designed to hold a large volume of coolant
so that the coolant is also exposed to a large volume of
air. The object being to transfer heat produced during
Fig. 4—Engine Coolant Circulation (Six-Cylinder)
combustion to the coolant and then to transfer heat in
the coolant to air flowing passed the radiator.
Radiators are of the cross-flow type (Fig. 5). The
water flows horizontally from the input (left) tank
through the individual cores to the output (right) tank.
Radiators used on vehicles equipped with automatic
transmission may, in some instances, have oil coolers
into the right (output) tank. Inlet and outlet fittings for
transmission fluid circulation are positioned vertically on
the tank.
Radiator Cap
The pressure type radiator filler cap is designed to
operate the cooling system at higher than atmospheric
pressure. The higher pressure raises the boiling point of
the coolant, which increases the efficiency of the radiator.
The radiator filler cap contains a pressure relief valve
and a vacuum relief valve. The pressure relief valve is
E N G I N E C O O L I N G 6 K -3
LIGHT DUTY TRUCK SERVICE MANUAL