Cadillac 60 Series 1963 Shop Manual page 272

ENGINE COOLING
11-1
GENERAL DESCRIPTION
The cooling system of all 1963 Cadillac engines
is of the low capacity type. This is made possible
by the small cylinder head area exposed to flame
and the high mechanical and combustion effi-
ciencies. With this design, the amount of heat
developed in the engine is decreased and less
coolant is required for necessary engine cooling.
A pressure operated vent type radiator cap
keeps coolant from escaping through the overflow
until the opening pressure is reached. The boiling
point of the coolant is thus raised, reducing the
possibility of coolant loss.
A four-bladed fan is used on standard cars; a
five-bladed aluminum fan with a fan shroud is
used on Air Conditioned cars. The transmission
fluid cooler is located in the lower tank of the
radiator.
A die cast aluminum water pump is centrally
mounted on the front of the engine front cover.
It is driven by "V" belts, which also drive the
generator, power steering pump, and refrigerant
compressor on Air Conditioned cars. Coolant is
drawn from the bottom of the radiator and de-
livered to both cylinder banks at the same time.
The coolant circulates around the cylinders and
up through drilled holes to the cylinder heads.
After circulating through the heads, it flows to
the thermostat housing, located at the top of the
cylinder head water outlet pipe, Fig. 11-1.
When the thermostat is closed, coolant from
the cylinder heads is drawn through a by-pass
passage in the cylinder head water outlet pipe to
the water pump and recirculated. When the engine
is sufficiently warm, the thermostat will open and
coolant will flow to the upper radiator tank, where
it is cooled as it circulates down through the
radiator core, completing the cycle.
A thermostatically controlled clutch is used in
conjunction with a five-bladed fan on Air Con-
ditioned cars. The clutch is designed with an
internal bi-metal control valve which makes the
clutch sensitive to engine speed and under hood
air temperature. With this design, engine cool-
ing is improved and fan noise is reduced at low
car speeds.
When car speed is below 70 MPH, the clutch is
disengaged sufficiently to control fan noise while
providing adequate fan speed. The large diameter
and greater pitch five-bladed fan will provide
improved engine cooling even though the fan is
running at reduced speeds. When car speed is
above 70 MPH the clutch will engage to provide
adequate fan speed for engine cooling.
The water pump is serviced only as an assem-
bly. The thermostatically controlled clutch, used
on Air Conditioned cars, is also serviced only
as an assembly.
I
Fig. 11-1 Flow of Coolant