1998 DODGE RAM 1500 coolant temperature

DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
(1) Attach one end of a hose to the draincock. Put
the other end into a clean container.
(2)DO NOT REMOVE THE RADIATOR CAP
when draining the coolant from the reservoir/over-
flow tank. Open radiator draincock and when the
tank is empty, remove the radiator cap and continue
draining the cooling system.
(3) If draining the entire engine, remove the cylin-
der block drain plugs. Refer to (Fig. 6) or (Fig. 7).STANDARD PROCEDURE - REFILLING
COOLING SYSTEM - ALL GAS ENGINES
WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
Clean cooling system prior to refilling. (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(1) Install cylinder block drain plugs. Coat the
threads with MopartThread Sealant with Teflon.
(2) Close radiator petcock.
(3) Fill cooling system with a 50/50 mixture of
water and antifreeze.
(4) Fill coolant reserve/overflow tank to MAX mark
on bottle.
(5) Start and operate engine until thermostat
opens (upper radiator hose warm to touch).
(6) If necessary, add a 50/50 water and antifreeze
mixture to the coolant reserve/overflow tank. This is
done to maintain coolant level between the MAX and
MIN marks. The level in the reserve/overflow tank
may drop below the MIN mark after three or four
warm-up and cool-down cycles.
STANDARD PROCEDURE - DRAINING COOLING
SYSTEM 5.9L DIESEL ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAIN PLUG WITH SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
(1) Start the engine and place the heater control
temperature selector in the Full-On position.
(2) Turn the ignition off.
(3) Do not remove radiator cap when draining cool-
ant from reserve/overflow tank. Open radiator drain
plug and when tank is empty, remove radiator cap. If
the coolant reserve/overflow tank does not drain,
(Refer to 7 - COOLING - DIAGNOSIS AND TEST-
ING). The coolant need not be removed from tank
unless the system is being refilled with fresh mix-
ture.
(4) Remove radiator pressure cap.
Fig. 6 Drain PlugsÐGas Powered EnginesÐTypical
1 - BLOCK DRAIN PLUG
Fig. 7 Drain Plug - 3.7L/4.7L Engine
1 - CYLINDER BLOCK DRAIN PLUG
2 - EXHAUST MANIFOLD AND HEAT SHIELD
7 - 18 COOLINGDR
COOLING (Continued)

ENGINE
TABLE OF CONTENTS
page page
COOLANT
DESCRIPTION
DESCRIPTION - ENGINE COOLANT.......31
DESCRIPTION - HOAT COOLANT.........32
OPERATION...........................33
COOLANT RECOVERY CONTAINER- GAS
ENGINES
DESCRIPTION.........................33
OPERATION...........................33
REMOVAL.............................33
INSTALLATION.........................33
RADIATOR FAN - GAS ENGINES
REMOVAL.............................33
CLEANING............................34
INSPECTION..........................34
INSTALLATION.........................34
RADIATOR FAN - 5.9L DIESEL
REMOVAL.............................35
CLEANING............................35
INSPECTION..........................35
INSTALLATION.........................36
ENGINE BLOCK HEATER
DESCRIPTION.........................36
OPERATION...........................36
DIAGNOSIS AND TESTING - ENGINE BLOCK
HEATER ............................36
REMOVAL.............................37
INSTALLATION.........................37
ENGINE BLOCK HEATER - 5.9L DIESEL
DESCRIPTION.........................37
OPERATION...........................38
REMOVAL.............................38
INSTALLATION.........................38
ENGINE COOLANT TEMPERATURE SENSOR
DESCRIPTION.........................38
OPERATION...........................38
REMOVAL.............................39
INSTALLATION.........................41
ENGINE COOLANT THERMOSTAT- 5.7L
DESCRIPTION.........................41
OPERATION...........................41
DIAGNOSIS AND TESTINGÐTHERMOSTAT . . . 42
REMOVAL.............................42
INSTALLATION.........................43
ENGINE COOLANT THERMOSTAT - 3.7L/4.7L
DESCRIPTION.........................44
OPERATION...........................44
DIAGNOSIS AND TESTINGÐTHERMOSTAT . . . 44
REMOVAL.............................45INSTALLATION.........................45
ENGINE COOLANT THERMOSTAT - 5.9L
DIESEL
DESCRIPTION.........................46
OPERATION...........................46
DIAGNOSIS AND TESTING - THERMOSTAT . . . 47
REMOVAL.............................47
INSTALLATION.........................47
ENGINE COOLANT THERMOSTAT - 8.0L
DESCRIPTION.........................48
OPERATION...........................48
DIAGNOSIS AND TESTING - THERMOSTAT . . . 48
REMOVAL.............................49
INSTALLATION.........................49
FAN DRIVE VISCOUS CLUTCH-GAS ENGINES
DESCRIPTION.........................50
OPERATION...........................50
DIAGNOSIS AND TESTING - VISCOUS FAN
DRIVE..............................50
FAN DRIVE VISCOUS CLUTCH - 5.9L DIESEL
DESCRIPTION.........................52
OPERATION...........................52
DIAGNOSIS AND TESTING -
ELECTRONICALLY CONTROLLED VISCOUS
FAN DRIVE..........................52
RADIATOR-3.7L/4.7L/5.7L
DESCRIPTION.........................54
OPERATION...........................54
DIAGNOSIS AND TESTING - RADIATOR
COOLANT FLOW......................54
REMOVAL.............................54
CLEANING............................55
INSPECTION..........................55
INSTALLATION.........................55
RADIATOR - 5.9L DIESEL
DESCRIPTION.........................56
OPERATION...........................56
DIAGNOSIS AND TESTING - RADIATOR
COOLANT FLOW......................56
REMOVAL.............................56
CLEANING............................56
INSPECTION..........................56
INSTALLATION.........................57
RADIATOR PRESSURE CAP
DESCRIPTION.........................57
OPERATION...........................58
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - RADIATOR
CAP-TO-FILLER NECK SEAL.............58
7 - 30 ENGINEDR

DIAGNOSIS AND TESTING - RADIATOR
CAP................................58
CLEANING............................59
INSPECTION..........................59
WATER PUMP - 3.7L/4.7L
DESCRIPTION
DESCRIPTION - WATER PUMP...........59
DESCRIPTION - WATER PUMP BYPASS....59
OPERATION
OPERATIONÐWATER PUMP............60
OPERATION - WATER PUMP BYPASS.....60
REMOVAL.............................60
CLEANING............................61
INSPECTION..........................61
INSTALLATION.........................61
WATER PUMP - 5.9L DIESEL
DESCRIPTION.........................62OPERATION...........................62
DIAGNOSIS AND TESTINGÐWATER PUMP . . . 62
REMOVAL.............................62
CLEANING............................62
INSPECTION..........................62
INSTALLATION.........................62
WATER PUMP - 5.7L
REMOVAL.............................63
INSTALLATION.........................63
WATER PUMP - 8.0L
DIAGNOSIS AND TESTING - WATER PUMP . . . 63
REMOVAL.............................64
CLEANING............................66
INSPECTION..........................66
INSTALLATION.........................66
COOLANT
DESCRIPTION
DESCRIPTION - ENGINE COOLANT
ETHYLENE-GLYCOL MIXTURES
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only MopartAntifreeze/Coolant, 5
year/100,000 Mile Formula (ethylene-glycol base cool-
ant with corrosion inhibitors called HOAT, for Hybrid
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% distilled water to obtain a freeze
point of -37ÉC (-35ÉF).
The required ethylene-glycol (antifreeze) and water
mixture depends upon the climate and vehicle oper-
ating conditions. The antifreeze concentrationmust
alwaysbe a minimum of 44 percent, year-round in
all climates.If percentage is lower than 44 per-
cent, engine parts may be eroded by cavitation,
and cooling system components may be
severely damaged by corrosion.Maximum protec-
tion against freezing is provided with a 68% anti-
freeze concentration, which prevents freezing down to
-67.7É C (-90É F). A higher percentage will freeze at a
warmer temperature. Also, a higher percentage of
antifreeze can cause the engine to overheat becausethe specific heat of antifreeze is lower than that of
water.
Use of 100 percent ethylene-glycol will cause for-
mation of additive deposits in the system, as the cor-
rosion inhibitive additives in ethylene-glycol require
the presence of water to dissolve. The deposits act as
insulation, causing temperatures to rise to as high as
149É C (300É F). This temperature is hot enough to
melt plastic and soften solder. The increased temper-
ature can result in engine detonation. In addition,
100 percent ethylene-glycol freezes at 22É C (-8É F ).
PROPYLENE-GLYCOL MIXTURES
It's overall effective temperature range is smaller
than that of ethylene-glycol. The freeze point of 50/50
propylene-glycol and water is -32É C (-26É F). 5É C
higher than ethylene-glycol's freeze point. The boiling
point (protection against summer boil-over) of propy-
lene-glycol is 125É C (257ÉF)at96.5 kPa (14 psi),
compared to 128É C (263É F) for ethylene-glycol. Use
of propylene-glycol can result in boil-over or freeze-up
on a cooling system designed for ethylene-glycol. Pro-
pylene glycol also has poorer heat transfer character-
istics than ethylene glycol. This can increase cylinder
head temperatures under certain conditions.
Propylene-glycol/ethylene-glycol Mixtures can
cause the destabilization of various corrosion inhibi-
tors, causing damage to the various cooling system
components. Also, once ethylene-glycol and propy-
lene-glycol based coolants are mixed in the vehicle,
conventional methods of determining freeze point will
not be accurate. Both the refractive index and spe-
cific gravity differ between ethylene glycol and propy-
lene glycol.
DRENGINE 7 - 31

DESCRIPTION - HOAT COOLANT
WARNING: ANTIFREEZE IS AN ETHYLENE-GLYCOL
BASE COOLANT AND IS HARMFUL IF SWAL-
LOWED OR INHALED. IF SWALLOWED, DRINK
TWO GLASSES OF WATER AND INDUCE VOMIT-
ING. IF INHALED, MOVE TO FRESH AIR AREA.
SEEK MEDICAL ATTENTION IMMEDIATELY. DO NOT
STORE IN OPEN OR UNMARKED CONTAINERS.
WASH SKIN AND CLOTHING THOROUGHLY AFTER
COMING IN CONTACT WITH ETHYLENE-GLYCOL.
KEEP OUT OF REACH OF CHILDREN. DISPOSE OF
GLYCOL BASE COOLANT PROPERLY, CONTACT
YOUR DEALER OR GOVERNMENT AGENCY FOR
LOCATION OF COLLECTION CENTER IN YOUR
AREA. DO NOT OPEN A COOLING SYSTEM WHEN
THE ENGINE IS AT OPERATING TEMPERATURE OR
HOT UNDER PRESSURE, PERSONAL INJURY CAN
RESULT. AVOID RADIATOR COOLING FAN WHEN
ENGINE COMPARTMENT RELATED SERVICE IS
PERFORMED, PERSONAL INJURY CAN RESULT.
CAUTION: Use of Propylene-Glycol based coolants
is not recommended, as they provide less freeze
protection and less corrosion protection.
The cooling system is designed around the coolant.
The coolant must accept heat from engine metal, in
the cylinder head area near the exhaust valves and
engine block. Then coolant carries the heat to the
radiator where the tube/fin radiator can transfer the
heat to the air.
The use of aluminum cylinder blocks, cylinder
heads, and water pumps requires special corrosion
protection. MopartAntifreeze/Coolant, 5
Year/100,000 Mile Formula (MS-9769), or the equiva-
lent ethylene-glycol base coolant with organic corro-
sion inhibitors (called HOAT, for Hybrid Organic
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% ethylene-glycol and 50% distilled
water to obtain a freeze point of -37ÉC (-35ÉF). If it
loses color or becomes contaminated, drain, flush,
and replace with fresh properly mixed coolant solu-
tion.
CAUTION: MoparTAntifreeze/Coolant, 5
Year/100,000 Mile Formula (MS-9769) may not be
mixed with any other type of antifreeze. Mixing of
coolants other than specified (non-HOAT or other
HOAT), may result in engine damage that may not
be covered under the new vehicle warranty, and
decreased corrosion protection.
COOLANT PERFORMANCE
The required ethylene-glycol (antifreeze) and water
mixture depends upon climate and vehicle operating
conditions. The coolant performance of various mix-
tures follows:
Pure Water-Water can absorb more heat than a
mixture of water and ethylene-glycol. This is for pur-
pose of heat transfer only. Water also freezes at a
higher temperature and allows corrosion.
100 percent Ethylene-Glycol-The corrosion
inhibiting additives in ethylene-glycol need the pres-
ence of water to dissolve. Without water, additives
form deposits in system. These act as insulation
causing temperature to rise to as high as 149ÉC
(300ÉF). This temperature is hot enough to melt plas-
tic and soften solder. The increased temperature can
result in engine detonation. In addition, 100 percent
ethylene-glycol freezes at -22ÉC (-8ÉF).
50/50 Ethylene-Glycol and Water-Is the recom-
mended mixture, it provides protection against freez-
ing to -37ÉC (-34ÉF). The antifreeze concentration
must alwaysbe a minimum of 44 percent, year-
round in all climates. If percentage is lower, engine
parts may be eroded by cavitation. Maximum protec-
tion against freezing is provided with a 68 percent
antifreeze concentration, which prevents freezing
down to -67.7ÉC (-90ÉF). A higher percentage will
freeze at a warmer temperature. Also, a higher per-
centage of antifreeze can cause the engine to over-
heat because specific heat of antifreeze is lower than
that of water.
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
COOLANT SELECTION AND ADDITIVES
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only MopartAntifreeze/Coolant, 5
Year/100,000 Mile Formula (glycol base coolant with
corrosion inhibitors called HOAT, for Hybrid Organic
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% distilled water to obtain to obtain a
freeze point of -37ÉC (-35ÉF). If it loses color or
becomes contaminated, drain, flush, and replace with
fresh properly mixed coolant solution.
CAUTION: Do not use coolant additives that are
claimed to improve engine cooling.
7 - 32 ENGINEDR
COOLANT (Continued)

OPERATION
Coolant flows through the engine block absorbing
the heat from the engine, then flows to the radiator
where the cooling fins in the radiator transfers the
heat from the coolant to the atmosphere. During cold
weather the ethylene-glycol or propylene-glycol cool-
ant prevents water present in the cooling system
from freezing within temperatures indicated by mix-
ture ratio of coolant to water.
COOLANT RECOVERY
CONTAINER- GAS ENGINES
DESCRIPTION
The coolant reserve/overflow tank is mounted on
top of the fan shroud, and is made of high tempera-
ture plastic (Fig. 1).
OPERATION
The coolant reserve/overflow system works in con-
junction with the radiator pressure cap. It utilizes
thermal expansion and contraction of coolant to keep
coolant free of trapped air. It provides a volume for
expansion and contraction of coolant. It also provides
a convenient and safe method for checking coolant
level and adjusting level at atmospheric pressure.
This is done without removing the radiator pressure
cap. The system also provides some reserve coolantto the radiator to cover minor leaks and evaporation
or boiling losses.
As the engine cools, a vacuum is formed in the
cooling system of both the radiator and engine. Cool-
ant will then be drawn from the coolant tank and
returned to a proper level in the radiator.
REMOVAL
(1) Remove recovery hose from radiator.
(2) Remove the coolant container to fan shroud
mounting bolt.
(3) Tilt the container backward towards the engine
to disengage the mounting pin locking features and
lift the container away from the fan shroud (Fig. 1).
INSTALLATION
(1) Align the coolant container mounting pins into
the slots on the fan shroud and push the container
onto the fan shroud.
(2) Secure the container to the fan shroud with the
bolt. Tighten to 8.5N´m (75 in-lbs).
NOTE: Ensure that the locking feature on the
mounting pins has engaged.
(3) Connect the recovery hose to the radiator (Fig.
1).
RADIATOR FAN - GAS
ENGINES
REMOVAL
CAUTION: If the viscous fan drive is replaced
because of mechanical damage, the cooling fan
blades should also be inspected. Inspect for fatigue
cracks, loose blades, or loose rivets that could
have resulted from excessive vibration. Replace fan
blade assembly if any of these conditions are
found. Also inspect water pump bearing and shaft
assembly for any related damage due to a viscous
fan drive malfunction.
(1) Disconnect negative battery cable from battery.
(2) Remove coolant reserve/overflow container from
fan shroud and lay aside.Do Notdisconnect the
hoses or drain coolant from the container.
(3) The thermal viscous fan drive/fan blade assem-
bly is attached (threaded) to the water pump hub
shaft (Fig. 3). Remove the fan blade/viscous fan drive
assembly from the water pump by turning the
mounting nut counterclockwise as viewed from the
front. Threads on the viscous fan drive areRIGHT-
HAND.A 36 MM Fan Wrench should be used to pre-
vent pulley from rotating (Fig. 2).
Fig. 1 Coolant Recovery Bottle - Gas Engine
1 - SCREW
2 - COOLANT RECOVERY CONTAINER
3 - RADIATOR/RADIATOR CAP
4 - FAN SHROUD
DRENGINE 7 - 33
COOLANT (Continued)

INSTALLATION
(1) Install fan blade assembly to electrically con-
trolled viscous fan drive. Tighten mounting bolts to
24 N´m (18 ft. lbs.) torque.
(2) Position the fan blade/viscous fan drive to the
vehicle as an assembly.
(3) Install the viscous fan drive assembly onto fan
pulley hub shaft (Fig. 4). Tighten mounting nut to
115 N´m (85 ft. lbs.) torque.
(4) Install upper fan shroud. Make sure the upper
shroud locks into the tabs on the lower radiator.
(5) Install two upper shroud mounting bolts.
Tighten to 11.8 N´m (105 in. lbs.) torque.
(6) Position the electronically controlled viscous
fan drive wiring into the channel in the upper fan
shroud (Fig. 5). Make sure the wiring is not pinched.
(7) Install the lower fan shroud into position and
verify the two locking tabs have seated.
(8) Install two push pin fasteners to lock lower fan
shroud to the main assembly.
NOTE: Verify that the fan drive electrical wire does
not interfere with fan blade travel when the fan
blade is spun by hand.
(9) Connect the wiring harness connector and
install the harness bracket to the upper radiator
shroud.(10) Install the coolant recovery container (Refer to
7 - COOLING/ENGINE/COOLANT RECOVERY
CONTAINER - INSTALLATION).
(11) Connect the battery negative cables.
NOTE:
Viscous Fan Drive Fluid Pump Out Requirement:
After installing a new viscous fan drive, bring the
engine speed up to approximately 2000 rpm and
hold for approximately two minutes. This will
ensure proper fluid distribution within the drive.
ENGINE BLOCK HEATER
DESCRIPTION
WARNING: DO NOT OPERATE ENGINE UNLESS
BLOCK HEATER CORD HAS BEEN DISCONNECTED
FROM POWER SOURCE AND SECURED IN PLACE.
THE POWER CORD MUST BE SECURED IN ITS
RETAINING CLIPS AND ROUTED AWAY FROM
EXHAUST MANIFOLDS AND MOVING PARTS.
An optional engine block heater is available with
all models. The heater is equipped with a power cord.
The cord is attached to an engine compartment com-
ponent with tie-straps. The heater warms the engine
providing easier engine starting and faster warm-up
in low temperatures. The heater is mounted in a core
hole of the engine cylinder block in place of a freeze
plug with the heating element immersed in engine
coolant. The 3.7L/4.7L gas powered engines have the
block heater located to the rear on the right side of
the engine (Fig. 6).
OPERATION
The heater warms the engine coolant providing
easier engine starting and faster warm-up in low
temperatures. Connecting the power cord to a
grounded 110-120 volt AC electrical outlet with a
grounded three wire extension cord provides the elec-
tricity needed to heat the element.
DIAGNOSIS AND TESTING - ENGINE BLOCK
HEATER
If the unit does not operate, possible causes can be
either the power cord or the heater element. Test the
power cord for continuity with a 110-volt voltmeter or
110-volt test light. Test heater element continuity
with an ohmmeter or a 12-volt test light.
CAUTION: To prevent damage, the power cord must
be secured in it's retainer clips and away from any
components that may cause abrasion or damage,
such as linkages, exhaust components, etc.
Fig. 5 Electronically Controlled Viscous Fan Drive
Wiring
1 - UPPER SHROUD
2 - WIRING
3 - GROMMET
7 - 36 ENGINEDR
RADIATOR FAN - 5.9L DIESEL (Continued)

OPERATION
The heater warms the engine coolant providing
easier engine starting and faster warm-up in low
temperatures. Connecting the power cord to a
grounded 110-120 volt AC electrical outlet with a
grounded three wire extension cord provides the elec-
tricity needed to heat the element.
REMOVAL
(1) Disconnect the battery negative cables.
(2) Drain coolant from radiator and cylinder block
(Refer to 7 - COOLING - STANDARD PROCE-
DURE).
(3) Unscrew the power cord retaining cap and dis-
connect cord from heater element.
(4) Using a suitable size socket, loosen and remove
the block heater element (Fig. 9).
INSTALLATION
(1) Clean and inspect the threads in the cylinder
block.
(2) Coat heater element threads with Mopart
Thread Sealer with Teflon.
(3) Screw block heater into cylinder block and
tighten to 55 N´m (41 ft. lbs.).
(4) Connect block heater cord and tighten retain-
ing cap.
(5) Fill cooling system with recommended coolant
(Refer to 7 - COOLING - STANDARD PROCE-
DURE).
(6) Start and warm the engine.
(7) Check block heater for leaks.
ENGINE COOLANT
TEMPERATURE SENSOR
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is
used to sense engine coolant temperature. The sensor
protrudes into an engine water jacket.
The ECT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as engine coolant
temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resis-
tance (voltage) in the sensor increases.
OPERATION
At key-on, the Powertrain Control Module (PCM)
sends out a regulated 5 volt signal to the ECT sensor.
The PCM then monitors the signal as it passes
through the ECT sensor to the sensor ground (sensor
return).
When the engine is cold, the PCM will operate in
Open Loop cycle. It will demand slightly richer air-
fuel mixtures and higher idle speeds. This is done
until normal operating temperatures are reached.
The PCM uses inputs from the ECT sensor for the
following calculations:
²for engine coolant temperature gauge operation
through CCD or PCI (J1850) communications
²Injector pulse-width
²Spark-advance curves
²ASD relay shut-down times
²Idle Air Control (IAC) motor key-on steps
²Pulse-width prime-shot during cranking
²O2 sensor closed loop times
²Purge solenoid on/off times
²EGR solenoid on/off times (if equipped)
²Leak Detection Pump operation (if equipped)
²Radiator fan relay on/off times (if equipped)
²Target idle speed
Fig. 8 Engine Block Heater ± 5.9L Diesel Engine
1 - BLOCK HEATER
Fig. 9 Block Heater - 5.9L Diesel Engine
1 - BLOCK HEATER
7 - 38 ENGINEDR
ENGINE BLOCK HEATER - 5.9L DIESEL (Continued)

REMOVAL
3.7L V-6
The Engine Coolant Temperature (ECT) sensor on
the 3.7L engine is installed into a water jacket at
front of intake manifold near rear of generator (Fig.
10).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Partially drain the cooling system.
(2) Disconnect the electrical connector from the
sensor.
(3) Remove the sensor from the intake manifold.
4.7L V-8
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE ENGINE COOLANT TEMPERATURE (ECT)
SENSOR.
The Engine Coolant Temperature (ECT) sensor on
the 4.7L V-8 engine is located near the front of the
intake manifold (Fig. 11).(1) Partially drain the cooling system. Refer to 7,
COOLING.
(2) Disconnect the electrical connector from the
ECT sensor.
(3) Remove the sensor from the intake manifold.
5.7L V-8
The Engine Coolant Temperature (ECT) sensor on
the 5.7L engine is located under the air conditioning
compressor (Fig. 12). It is installed into a water
jacket at the front of the cylinder block (Fig. 13).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Partially drain the cooling system.
(2) Remove fan belt. Refer to Accessory Drive in
Cooling section.
(3) Carefully unbolt air conditioning compressor
from front of engine. Do not disconnect any A/C hoses
from compressor. Temporarily support compressor to
gain access to ECT sensor. Refer to Heating and Air
Conditioning section for information.
(4) Disconnect electrical connector from sensor
(Fig. 13).
(5) Remove sensor from cylinder block.
Fig. 10 MAP SENSOR / ECT SENSOR - 3.7L V-6
1 - MOUNTING SCREWS
2 - MAP SENSOR
3 - ECT SENSOR
4 - FRONT OF INTAKE MANIFOLD
Fig. 11 ECT SENSOR - 4.7L V-8
1 - ECT SENSOR
2 - MOUNTING BOLTS (2)
3 - MAP SENSOR
4 - INTAKE MANIFOLD
DRENGINE 7 - 39
ENGINE COOLANT TEMPERATURE SENSOR (Continued)