TM 5-4310-354-14
temperatures should be within plus or minus two
4-48.
Water Temperature
Sending
Unit
and
percent; if not, water temperature gauge is faulty and
Shutdown Switch.
shall be replaced.
a. Removal. Remove radiator cap, open radiator
drain cock, drain coolant from radiator to a level below
(2) Temperature shutdown switch.
Attach
the engine cylinder head; then, close drain cock.
leads from an ohmmeter to the terminals of the
Unscrew and remove the water temperature sending unit
shutdown switch. Heat a container of water and use a
from the engine cylinder head on the flywheel end of the
calibrated thermometer to check temperature of the
engine. Disconnect the two wire assemblies from water
heated liquid.
Immerse the sensing probe of the
temperature shutdown switch and remove the switch
shutdown switch in the heated liquid. The shutdown
from engine cylinder head next to instrument panel.
switch is normally closed and designed to open at
temperature of 215F, plus or minus 5 F. Reading on
b. Cleaning and Inspection.
Wipe the water
ohmmeter should be zero until this temperature is
temperature sending unit sensing bulb with a clean, lint-
reached at which time reading will be infinity, indicating
free cloth and inspect for damage to bulb and threads.
switch has opened.
When switch opens, check
Wipe the water temperature shutdown switch sensing
temperature reading on the thermometer. If the switch
bulb with a clean, lint-free cloth. Inspect for damage to
has opened within the design temperature setting, lower
sensing bulb, threads, and wire terminals.
the temperature of the heated liquid, observing the
ohmmeter. The switch should close at approximately
c. Repair.
Repair of the water temperature
20 differential from opening; ohmmeter reading
sensing unit is limited to the replacement of the water
returning to zero. If the shutdown switch does not
temperature gauge with sensing bulb. Also, replace a
operate properly, it shall be replaced.
Disconnect
defective water temperature shutdown switch.
ohmmeter leads and remove the shutdown switch from
test setup.
d. Testing. Test the water temperature gauge and
sensing bulb and the water temperature shutdown
e. Installation.
Install the water temperature
switch as follows:
shutdown switch in the engine cylinder head next to the
instrument panel. Connect the two wires to the switch
(1) Water temperature gauge.
Place a
terminals (refer to wiring diagram, figure 1-3). Install the
calibrated thermometer in a container of water and heat
water temperature sensing unit in the cylinder head on
the water to a temperature of from 90 to 212 F (32 to
the flywheel end of the engine. Service the radiator as
100C). Place the water temperature gauge sensing
shown in figure 3-6. Install radiator cap.
bulb in the water and observe temperature reading on
gauge compared to the thermometer reading. The
4-60
