Hudson 1948 - 1952, Service Manual

Page: 128 / 333

DESCRIPTION AND OPERATION
The cooling system is of the pressure type and has a
cellular tubular radiator, a centrifugal six vane impeller
pump and a four blade radiator fan with the blades un-
evenly spaced to minimize noise.
Six cylinder engine blocks contain a brass water distribut-
ing tube with holes properly spaced to direct the flow of
water around the exhaust valves for cooling purposes.
Eight cylinder engine blocks have a water jacket cover on
the left side of the block.
By-pass thermostats are used to permit rapid. engine
warm-up by restricting circulation of the coolant through
the radiator and by-passing if through the cylinder block
until the coolant temperature rises sufficiently to open the
thermostat. The temperature range of the thermostats is as
follows -
Starts to open 150° to 155.
Fully open at 185°.
All models use a pressure type radiator cap which is
designed to maintain a constant pressure in the cooling
system under normal Operating conditions.
A pressurized system provides advantages by protection
against loss of coolant or anti-freeze solutions by evapora-
tion since the increased pressure of the system raises the
boiling pointof water from a normal 212° F at sea level to
approximately 2300 F with a 7 lb. pressure cap.
CAUTION: When removing pressure cap while the engine is
hot, always turn cap slowly counter clockwise until the stop is
reached. Keep the cap in this position until all pressure is dissi-
pated; then turn cap fully and remove.
DRAINING SYSTEM
To drain the cooling system, open the radiator drain cock
located at the lower right hand corner and remove the drain
plug in the cylinder block located at the rear left hand side
and remove radiator cap.
RUST AND SCALE DEPOSITS
Scale or rust tends to obstruct the flow of coolant through
the water passages of the cylinder block and radiator, and
when such formation is excessive, it prevents proper heat
dissipation and resultant overheating. This, in turn, causes
loss in lubrication efficiency and accumulation of carbon,
varnish and sludge.
If overheating exists due to clogging of the engine portion
of the cooling system, the condition should be corrected by
the use of a reputable solvent, instead of reverse flushing.
REVERSE FLUSHING
Reverse flushing of the cooling system is the forcing of
water through the radiator using air pressure and flushing in
a direction opposite to that of the normal flow of water.
Reverse flushing is necessary in order to get behind the
deposits and force them out.
The procedure for reverse flushing is as follows:
1. Disconnect hoses from engine.
FIGURE 1
5 - 2 COOLING SYSTEM