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ENGINE
ENGINE COOLANT TEMPERATURE SENSOR (Continued)
INSTALLATION
(1) Install ECT sensor. Torque sensor to 19 N·m
(168 in. lbs.).
(2) Reconnect ECT sensor electrical sensor.
(3) Fill cooling system (Refer to 7 - COOLING/EN-
GINE - STANDARD PROCEDURE).
ENGINE COOLANT
THERMOSTAT
DESCRIPTION
DESCRIPTION - 2.0L/2.4L
The thermostat is located on the front of the
engine (radiator side) in the thermostat housing/cool-
ant outlet connector (Fig. 19). The thermostat has a
air bleed vent located in the flange and an O-ring
with a locating dimple incorporated on it. There is a
relief in the housing for positioning the air bleed.
DESCRIPTION - 2.7L
The thermostat is located on the lower left side of
engine, near the front (Fig. 20). The thermostat is on
the inlet side of the water pump. It has an air bleed
located in the thermostat flange. The air bleed allows
internal trapped air during cooling system filling to
be released.
OPERATION
The engine cooling thermostat is a wax pellet
driven, reverse poppet choke type. The thermostat is
designed to provide the fastest warm up possible by
preventing leakage through it and to guarantee a
minimum engine operating temperature of 88 to
93°C (192 to 199°F). The thermostat also will auto-
matically reach wide open so it will not restrict flow
to the radiator as temperature of the coolant rises in
hot weather to around 104°C (220°F). Above this
temperature the coolant temperature is controlled by
the radiator, fan, and ambient temperature, not the
thermostat.
The thermostat is operated by a wax filled con-
tainer (pellet) which is sealed. When heated coolant
reaches a predetermined temperature, the wax
expands enough to overcome the closing spring and
water pump pressure, which forces the valve to open.
DIAGNOSIS AND TESTING - ENGINE COOLANT
THERMOSTAT TESTING
The thermostat is operated by a wax filled con-
tainer (pellet) which is sealed. When heated coolant
reaches a predetermined temperature the wax pellet
expands enough to overcome the closing spring and
water pump pressure, which forces the valve to open.
Coolant leakage into the pellet will cause a thermo-
stat to fail open. Do not attempt to free up a thermo-
stat with a screwdriver.
The thermostat that opens too soon type failure
mode is included in the on-board diagnosis. The
check engine light will not be lit by an open too soon
condition. If it has failed open, a diagnostic trouble
code (DTC) will be set. Do not change a thermostat
for lack of heater performance or temperature gauge
position, unless a DTC is present. For other probable
causes, (Refer to 7 - COOLING/ENGINE - DIAGNO-
SIS AND TESTING). Thermostat failing shut is the
normal long term mode of failure, and normally, only
on high mileage vehicles. The temperature gauge will
indicate this. (Refer to 7 - COOLING/ENGINE -
DIAGNOSIS AND TESTING)
REMOVAL
REMOVAL - 2.0L/2.4L
WARNING: DO NOT REMOVE PRESSURE CAP OR
ANY HOSE WITH THE SYSTEM HOT AND UNDER
PRESSURE BECAUSE SERIOUS BURNS FROM
COOLANT CAN OCCUR.
(1) Partially drain cooling system below thermo-
stat level.
(2) Disconnect hoses at coolant outlet connector.
(3) Remove bolts attaching coolant outlet connector
(Fig. 19).
(4) Remove coolant outlet connector and thermo-
stat.
REMOVAL - 2.7L
(1) Disconnect negative cable from remote jumper
terminal.
WARNING: DO NOT REMOVE PRESSURE CAP OR
ANY HOSE WITH THE SYSTEM HOT AND UNDER
PRESSURE BECAUSE SERIOUS BURNS FROM
COOLANT CAN OCCUR.
(2) Drain cooling system (Refer to 7 - COOLING/
ENGINE - STANDARD PROCEDURE).
(3) Raise vehicle on hoist.
(4) Remove right front wheel and belt splash
shield.
(5) Remove accessory drive belts (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(6) Remove lower generator mounting bolt.
(7) Lower vehicle.
(8) Disconnect generator electrical connectors.
JR
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