Dodge Durango (HB). Manual — part 134
4.7L V-8
1. Apply thread sealant to sensor threads.
2. Install ECT sensor (1) to engine.
3. Tighten sensor to 11 N·m (97.3 in. lbs.) torque.
4. Connect electrical connector to sensor (1).
5. Fill cooling system (Refer to 7 - COOLING - STAN-
DARD PROCEDURE).
5.7L V-8
1. Apply thread sealant to sensor threads.
2. Install ECT sensor (3) to engine.
3. Tighten sensor to 11 N·m (97.3 in. lbs.) torque.
4. Connect electrical connector (2) to ECT sensor (3).
5. Fill the cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
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ENGINE
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THERMOSTAT-ENGINE COOLANT
DESCRIPTION
CAUTION: Do not operate an engine without a
thermostat, except for servicing or testing.
The thermostat on the 5.7L gas powered engine is
located beneath the thermostat housing (1) at the
front of the intake manifold.
On
the
3.7L/4.7L engine
the
thermostat
(4)
is
designed to block the flow of the coolant bypass jour-
nal by 50% instead of completely blocking the flow.
The thermostat is a wax pellet driven, reverse poppet
choke type.
Coolant leakage into the pellet container will cause
the thermostat to fail in the open position. Thermo-
stats very rarely stick. Do not attempt to free a ther-
mostat with a prying device.
The same thermostat is used for winter and summer
seasons. An engine should not be operated without a
thermostat, except for servicing or testing. Operating
without a thermostat causes longer engine warmup
time,
unreliable
warmup
performance,
increased
exhaust emissions and crankcase condensation that
can result in sludge formation.
OPERATION
The wax pellet is located in a sealed container at the
spring end of the thermostat. When heated, the pellet
expands, overcoming closing spring tension and water
pump pressure to force the valve to open.
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ENGINE
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DIAGNOSIS AND TESTING - THERMOSTAT
ON-BOARD DIAGNOSTICS
All gasoline powered models are equipped with On-Board Diagnostics for certain cooling system components.
Refer to On-Board Diagnostics (OBD) in the Diagnosis section of this group for additional information. If the pow-
ertrain control module (PCM) detects low engine coolant temperature, it will record a Diagnostic Trouble Code
(DTC) in the PCM memory. Do not change a thermostat for lack of heat as indicated by the instrument panel gauge
or by poor heater performance unless a DTC is present. Refer to the Diagnosis section of this group for other
probable causes. For other DTCs, (Refer to 25 - EMISSIONS CONTROL - DESCRIPTION)
The DTC can also be accessed through the DRB scan tool. Refer to the appropriate Powertrain Diagnostic Proce-
dures information for diagnostic information and operation of the DRB scan tool.
REMOVAL
5.7L ENGINE
If the thermostat is being replaced, be sure that the
replacement is the specified thermostat for the vehicle
model and engine type.
1. Disconnect the negative battery cable.
2. Drain the cooling system until the coolant level is
below the thermostat (Refer to 7 - COOLING -
STANDARD PROCEDURE)
3. Air Conditioned vehicles: Remove the support
bracket (generator mounting bracket-to-intake man-
ifold) (2) located near the rear of the generator.
Note: On air conditioning equipped vehicles, the
generator must be partially removed.
4. Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
5. Remove the generator mounting bolts. Do not
remove any of the wiring at the generator. If
equipped with 4WD, unplug the 4WD indicator lamp
wiring harness (located near rear of generator).
6. Remove the generator. Position the generator to
gain access for the thermostat gasket removal.
7. Remove the radiator upper hose clamp and upper
hose at the thermostat housing.
8. Position the wiring harness (behind thermostat
housing) to gain access to the thermostat housing.
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ENGINE
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9. Remove the thermostat housing mounting bolts,
thermostat housing (1), gasket ( 2) and thermostat
(3). Discard old gasket (3).
3.7L/4.7L ENGINE
If thermostat is being replaced, be sure that replace-
ment is specified thermostat for vehicle model and
engine type.
1. Disconnect negative battery cable at battery.
2. Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE)
3. Raise vehicle on hoist.
4. Remove splash shield.
5. Remove lower radiator hose clamp and lower radi-
ator hose at thermostat housing.
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ENGINE
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