Hudson 1948 - 1952, Service Manual

Page: 135 / 333

COOLING SYSTEM 5 - 9
Continue heating the water until the thermostat is
wide open. The thermometer should show 185° F.
Discard thermostats that:
Do not open completely.
Open at too low a temperature.
Open at too high a temperature.
A thermostat that opens too soon will cause the
engine to operate at too low a temperature and if it
opens too late or is sticking, it may cause the engine
to overheat.
WATER TEMPERATURE GAUGE
A new type cylinder head sender unit is used in the
temperature gauge which operates on an entirely
different principal. The unit has no moving parts.
A comparatively new sintered material which
has low resistance when hot and high resistance when
cold is the heart of the unit.
The sintered material is enclosed in the extreme
end of a sealed bulb which is installed in the
cylinder head on the left hand side near the front.
When the coolant is cold the high resistance in the unit
causes the instrument panel gauge to read at the cold end
of the dial with ignition switch turned on.
FIGURE 8
FIGURE 9
When the coolant is hot the low resistance in the unit causes the
instrument panel gauge to read at the hot side of the dial with
ignition switch on. Refer to figure 8 and 9.
SERVICE CHECKS
If the temperature gauge reads up-scale when the engine is cold,
check ground connection of the voltage regulator.
If the gauge shows a reading too low either the input
to the regulator is low or the regulator is inoperative
and should be replaced.
NOTE: Battery output should be checked before replac-
ing regulator.
It is not advisable to attempt any repairs or adjust-
ments to either unit of the gauge since they are factory
calibrated and any attempt to repair is impractical.
WATER JACKET PLUGS
(6 Cylinder)
The water jacket plugs used in the left side of the six
cylinder block are a drive fit and can be easily Installed
using Tool J-2793 as illustrated in Figure 10. Use a light
coat of Hudson perfect seal paste to facilitate installation
and improve the sealing.