Thermostat Testing - Jeep 1987 Wrangler Workshop Manual

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ENGINES
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COOLING SYSTEMS
CAUTION: Observe the recess in the cylinder
head and position the thermostat in the groove
(1). Next, install the replacement
gasket and thermostat housing. Tightening the
housing unevenly or with the thermostat out of
its recess will result in a cracked housing.
Tighten the housing bolts with 18 N-m (13 ft-lbs)
torque.
Install the radiator upper hose and intake
manifold hose.
Ensure that the radiator draincock is tightly
closed.
Fill the cooling system to the correct level with
the required coolant mixture. Refer to Coolant.
THERMOSTAT TESTING
Remove the thermostat. Refer to Thermostat
Removal.
Insert a 0.076mm (0.003-in) feeler gauge, with a
wire or string attached, between the thermostat
valve and seat.
WARNING: Antifreeze is poisonous. Keep out
of the reach of children.
A - Feeler Gauge
B - Thermostat
C - Thermometer
Submerge the thermostat in a container of pure
antifreeze and suspend it so that it does not
touch the sides or the bottom of the container.
Suspend a thermometer in the antifreeze so that
it does not touch the container.
WARNING: Do not breathe the vapor. Ensure
the test area is properly ventilated.
B-173