2002 JEEP LIBERTY engine coolant

(Mopar Radiator Kleen or equivalent) before flushing.
This will soften scale and other deposits and aid the
flushing operation.
CAUTION: Be sure instructions on the container are
followed.
REVERSE FLUSHING RADIATOR
Disconnect the radiator hoses from the radiator fit-
tings. Attach a section of radiator hose to the radia-
tor bottom outlet fitting and insert the flushing gun.
Connect a water supply hose and air supply hose to
the flushing gun.
CAUTION: The cooling system normally operates at
97-to-110 kPa (14- to-16 psi) pressure. Exceeding
this pressure may damage the radiator or hoses.
Allow the radiator to fill with water. When radiator
is filled, apply air in short blasts allowing radiator to
refill between blasts. Continue this reverse flushing
until clean water flows out through rear of radiator
cooling tube passages. For more information, refer to
operating instructions supplied with flushing equip-
ment. Have radiator cleaned more extensively by a
radiator repair shop.
REVERSE FLUSHING ENGINE
Drain the cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE). Remove the thermostat
housing and thermostat. Install the thermostat hous-
ing. Disconnect the radiator upper hose from the
radiator and attach the flushing gun to the hose. Dis-
connect the radiator lower hose from the water
pump. Attach a lead away hose to the water pump
inlet fitting.
CAUTION: Be sure that the heater control valve is
closed (heat off). This is done to prevent coolant
flow with scale and other deposits from entering
the heater core.
Connect the water supply hose and air supply hose
to the flushing gun. Allow the engine to fill with
water. When the engine is filled, apply air in short
blasts, allowing the system to fill between air blasts.
Continue until clean water flows through the lead
away hose. For more information, refer to operating
instructions supplied with flushing equipment.
Remove the lead away hose, flushing gun, water
supply hose and air supply hose. Remove the thermo-
stat housing (Refer to 7 - COOLING/ENGINE/EN-
GINE COOLANT THERMOSTAT - REMOVAL).
Install the thermostat and housing with a replace-
ment gasket (Refer to 7 - COOLING/ENGINE/EN-
GINE COOLANT THERMOSTAT -INSTALLATION). Connect the radiator hoses. Refill
the cooling system with the correct antifreeze/water
mixture (Refer to 7 - COOLING - STANDARD PRO-
CEDURE).
SPECIFICATIONS
TORQUE
DESCRIPTION N´m Ft. In.
Lbs. Lbs.
Automatic Belt Tensioner to
Mounting
BracketÐBolt
2.4L - Ð -
4.7L 41 30 Ð
Automatic Belt Tensioner
PulleyÐ
Bolt
(3.7L) 61 45 Ð
Block HeaterÐBolt
2.4L - Ð -
3.7L 2 Ð 17
Condenser to Radiator Bolts 8 70
Coolant Overflow Bottle to
Plenum mounting bolts - 2.4L
only8.5 75
Coolant Pressure Bottle to
Plenum mounting bolts -3.7L
only8.5 75
Electric Fan to Fan Shroud
bolts5.5 50
Fan Blade Assy. to Viscous
Drive
Bolts 3.7L 23 Ð 210
Fan Shroud to Radiator
Mounting Bolts8Ð70
Radiator Upper Isolator to
Crossmember - Bolts 9.5 Ð 85
Thermostat HousingÐBolts
2.4L - - Ð
4.7L 13 Ð 115
Water PumpÐBolts
2.4L Ð Ð Ð
4.7L 54 40 Ð
KJCOOLING 7 - 13
COOLING (Continued)

ENGINE
TABLE OF CONTENTS
page page
COOLANT RECOVERY PRESS CONTAINER
DESCRIPTION.........................19
OPERATION...........................19
ENGINE COOLANT TEMPERATURE SENSOR
DESCRIPTION.........................19
OPERATION...........................20
REMOVAL.............................20
INSTALLATION.........................21
ENGINE COOLANT THERMOSTAT
DESCRIPTION - 3.7L ENGINE.............21
OPERATION...........................21
DIAGNOSIS AND TESTING - THERMOSTAT . . . 21
REMOVAL - 3.7L ENGINE.................21
INSTALLATION - 3.7L ENGINE.............22
RADIATOR
DESCRIPTION.........................22
REMOVAL.............................23
CLEANING............................24
INSPECTION..........................24
INSTALLATION.........................24
RADIATOR PRESSURE CAP
DESCRIPTION.........................25
OPERATION...........................25
DIAGNOSIS AND TESTING - RADIATOR
PRESSURE CAP......................25CLEANING............................25
INSPECTION..........................25
RADIATOR FAN - ELECTRIC
DESCRIPTION.........................26
OPERATION...........................26
REMOVAL.............................26
INSTALLATION.........................27
RADIATOR - FAN - VISCOUS
DESCRIPTION.........................27
OPERATION...........................27
DIAGNOSIS AND TESTING - VISCOUS FAN
DRIVE..............................28
REMOVAL.............................28
CLEANING............................29
INSPECTION..........................29
INSTALLATION.........................29
WATER PUMP
DESCRIPTION
DESCRIPTION - WATER PUMP...........29
DESCRIPTION........................29
OPERATION - WATER PUMP..............30
REMOVAL.............................30
CLEANING............................31
INSPECTION..........................31
INSTALLATION.........................31
COOLANT RECOVERY PRESS
CONTAINER
DESCRIPTION
This system works along with the radiator pres-
sure cap. This is done by using thermal expansion
and contraction of the coolant to keep the coolant
free of trapped air. It provides:
²A volume for coolant expansion and contraction.
²A convenient and safe method for checking/ad-
justing coolant level at atmospheric pressure. This is
done without removing the radiator pressure cap.
²Some reserve coolant to 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.
The coolant reservoir/overflow system has a radia-
tor mounted pressurized cap, an overflow tube, and a
plastic coolant reservoir/overflow tank, mounted to
the right side of the cowl. It is mounted to the cowlwith two nuts on top, and a slide bracket on the bot-
tom.
OPERATION
The pressure chamber keeps the coolant free of
trapped air, provides a volume for expansion and con-
traction, and provides a convenient and safe method
for checking and adjusting coolant level at atmo-
spheric pressure. It also provides some reserve cool-
ant to cover minor leaks, evaporation or boiling
losses. The overflow chamber allows coolant recovery
in case of an overheat.
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.
KJENGINE 7 - 19

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
REMOVAL
2.4L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at left front of cylinder
head (Fig. 1).
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 cooling system.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from cylinder head.
3.7L
The Engine Coolant Temperature (ECT) sensor is
installed into a water jacket at front of intake mani-
fold near rear of generator (Fig. 2).
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 cooling system.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from intake manifold.
Fig. 1 ECT AND UPPER TIMING BELT COVER/
BOLTS-2.4L
1 - UPPER TIMING BELT COVER
2 - ELECTRICAL CONNECTOR (ECT)
3 - MOUNTING BOLTS (3)
Fig. 2 MAP SENSOR / ECT SENSOR - 3.7L
1 - MOUNTING SCREWS
2 - MAP SENSOR
3 - ECT SENSOR
7 - 20 ENGINEKJ
ENGINE COOLANT TEMPERATURE SENSOR (Continued)

INSTALLATION
(1) Apply thread sealant to sensor threads.
(2) Install sensor to engine.
(3) Tighten sensor to 11 N´m (8 ft. lbs.) torque.
(4) Replace any lost engine coolant.
ENGINE COOLANT
THERMOSTAT
DESCRIPTION - 3.7L ENGINE
CAUTION: Do not operate an engine without a ther-
mostat, except for servicing or testing.
A pellet-type thermostat controls the operating
temperature of the engine by controlling the amount
of coolant flow to the radiator. On all engines the
thermostat is closed below 195ÉF (90ÉC). Above this
temperature, coolant is allowed to flow to the radia-
tor. This provides quick engine warm up and overall
temperature control. On the 3.7L engine the thermo-
stat is designed to block the flow of the coolant
bypass journal by 50% instead of completely blocking
the flow. This design controls coolant temperature
more accurately (Fig. 3).
The same thermostat is used for winter and sum-
mer seasons. An engine should not be operated with-
out a thermostat, except for servicing or testing.
Operating without a thermostat causes other prob-
lems. These are: longer engine warmup time, unreli-
able warmup performance, increased exhaust
emissions and crankcase condensation. This conden-
sation 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.
DIAGNOSIS AND TESTING - THERMOSTAT
ON-BOARD DIAGNOSTICS
All models are equipped with On-Board Diagnos-
tics for certain cooling system components.If the pow-
ertrain control module (PCM) detects low engine
coolant temperature, it will record a Diagnostic Trou-
ble Code (DTC). For other DTC numbers, (Refer to 25
- EMISSIONS CONTROL - DESCRIPTION).
The DTC can also be accessed through the DRB
scan tool.
REMOVAL - 3.7L ENGINE
WARNING: DO NOT LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND PRESSURIZED.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
Do not waste reusable coolant. If solution is clean,
drain coolant into a clean container for reuse.
If thermostat is being replaced, be sure that
replacement 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
radiator hose at thermostat housing.
(6) Remove thermostat housing mounting bolts,
thermostat housing and thermostat (Fig. 4).
Fig. 3 Thermostat
1 - FROM HEATER
2 - FROM RADIATOR
3 - TO WATER PUMP
4 - ENGINE BYPASS
5 - THERMOSTAT
KJENGINE 7 - 21
ENGINE COOLANT TEMPERATURE SENSOR (Continued)

INSTALLATION - 3.7L ENGINE
(1) Clean mating areas of timing chain cover and
thermostat housing.
(2)
Install thermostat (spring side down) into
recessed machined groove on timing chain cover (Fig. 4).
(3) Position thermostat housing on timing chain
cover.
(4) Install two housing-to-timing chain cover bolts.
Tighten bolts to 13 N´m (115 in. lbs.) torque.
CAUTION: Housing must be tightened evenly and
thermostat must be centered into recessed groove
in timimg chain cover. If not, it may result in a
cracked housing, damaged timing chain cover
threads or coolant leaks.
(5)
Install lower radiator hose on thermostat housing.
(6) Install splash shield.
(7) Lower vehicle.
(8) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(9) Connect negative battery cable to battery.
(10) Start and warm the engine. Check for leaks.
RADIATOR
DESCRIPTION
All vehicles are equipped with a cross flow type
radiator with plastic side tanks (Fig. 5).Plastic tanks, while stronger than brass, are sub-
ject to damage by impact, such as from tools or
wrenches. Handle radiator with care.
Fig. 4 Thermostat and Thermostat Housing
1 - THERMOSTAT HOUSING
2 - THERMOSTAT LOCATION3 - THERMOSTAT AND GASKET
4 - TIMING CHAIN COVER
Fig. 5 Cross Flow Radiator - Typical
1 - RADIATOR
7 - 22 ENGINEKJ
ENGINE COOLANT THERMOSTAT (Continued)

REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR. REFER TO COOLING SYSTEM DRAIN-
ING.
Do not waste reusable coolant. If the solution is
clean, drain the coolant into a clean container for
reuse.
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER
6094) (Fig. 6). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-
ING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 7). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.
CAUTION: When removing the radiator or A/C con-
denser for any reason, note the location of all radi-
ator-to-body and radiator-to-A/C condenser rubber
air seals (Fig. 8). These are used at the top, bottom
and sides of the radiator and A/C condenser. To
prevent overheating, these seals must be installed
to their original positions.(1) Disconnect the negative battery cable at bat-
tery.
(2) Drain coolant from radiator (Refer to 7 -
COOLING - STANDARD PROCEDURE).
Fig. 6 Hose Clamp Tool - Typical
1 - HOSE CLAMP TOOL 6094
2 - HOSE CLAMP
Fig. 7 Clamp Number/Letter Location - Typical
1 - TYPICAL CONSTANT TENSION HOSE CLAMP
2 - CLAMP NUMBER/LETTER LOCATION
3 - TYPICAL HOSE
Fig. 8 Air Seals - Typical
1 - AIR DAM
2 - RADIATOR
3 - AIR DAM
4 - A/C CONDENSER
5 - AIR SEAL
KJENGINE 7 - 23
RADIATOR (Continued)

(3) Remove the front grill (Refer to 23 - BODY/EX-
TERIOR/GRILLE - REMOVAL).
(4) Remove the cooling fan from the engine, if
equipped.
(5) Remove the two radiator mounting bolts.
(6) Disconnect both transmission cooler lines from
radiator.
(7) Disconnect the connector for the electric fan.
(8) Disconnect the power steering cooler line from
cooler.
(9) Disconnect the radiator upper and lower hoses.
(10) Disconnect the overflow hose from radiator.
(11) The lower part of radiator is equipped with
two alignment dowel pins (Fig. 9). They are located
on the bottom of radiator tank and fit into rubber
grommets. These rubber grommets are pressed into
the radiator lower crossmember.
WARNING: THE AIR CONDITIONING SYSTEM (IF
EQUIPPED) IS UNDER A CONSTANT PRESSURE
EVEN WITH THE ENGINE OFF. REFER TO REFRIG-
ERANT WARNINGS IN, HEATING AND AIR CONDI-
TIONING BEFORE HANDLING ANY AIR
CONDITIONING COMPONENT.
NOTE: The radiator and radiator cooling fan can be
removed as an assembly. It is not necessary toremove the cooling fan before removing or install-
ing the radiator.
(12) Gently lift up and remove radiator from vehi-
cle. Be careful not to scrape the radiator fins against
any other component. Also be careful not to disturb
the air conditioning condenser (if equipped).
CLEANING
Clean radiator fins With the engine cold, apply cold
water and compressed air to the back (engine side) of
the radiator to flush the radiator and/or A/C con-
denser of debris.
INSPECTION
The radiator cooling fins should be checked for
damage or deterioration. Inspect cooling fins to make
sure they are not bent or crushed, these areas result
in reduced heat exchange causing the cooling system
to operate at higher temperatures. Inspect the plastic
end tanks for cracks, damage or leaks.
Inspect the radiator neck for damage or distortion.
INSTALLATION
CAUTION: Before installing the radiator or A/C con-
denser, be sure the radiator-to-body and radiator-to-
A/C condenser rubber air seals are properly
fastened to their original positions. These are used
at the top, bottom and sides of the radiator and A/C
condenser. To prevent overheating, these seals
must be installed to their original positions.
(1) Gently lower the radiator and fan shroud into
the vehicle. Guide the two radiator alignment dowels
into the rubber grommets located in lower radiator
crossmember.
(2) Connect the radiator upper and lower hoses
and hose clamps to radiator.
CAUTION: The tangs on the hose clamps must be
positioned straight down.
(3) Install coolant reserve/overflow tank hose at
radiator.
(4) Connect both transmission cooler lines at the
radiator.
(5) Install both radiator mounting bolts.
(6) Reconnect the electric cooling fan.
(7) Install the grill (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION).
(8) Reinstall the cooling fan to the engine.
(9) Rotate the fan blades (by hand) and check for
interference at fan shroud.
(10) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(11) Connect battery cable at battery.
(12) Start and warm engine. Check for leaks.
Fig. 9 Radiator Alignment Dowels - Typical
1 - RADIATOR
2 - ALIGNMENT DOWEL
3 - RADIATOR LOWER ISOLATOR
4 - RADIATOR LOWER CROSSMEMBER
7 - 24 ENGINEKJ
RADIATOR (Continued)

RADIATOR PRESSURE CAP
DESCRIPTION
The cooling system cap is located on the coolant
pressure bottle. The cap construction includes; stain-
less steel swivel top, rubber seals and retainer, main
spring, and a spring loaded valve (Fig. 10).
OPERATION
The pressure cap allows the cooling system to oper-
ate at higher than atmospheric pressure which raises
the coolant boiling point, thus allowing increased
radiator cooling capacity. The pressure cap releases
pressure at some point within a range of 110 kPa  
14 kPa (16 psi   2 psi).
A spring-loaded vent valve in the center of the cap
allows the system to pressurize and depressurize
without creating a vacuum. If the valve is stuck
open, coolant will escape to the overflow hose. There
is also a gasket in the cap to seal to the top of the
filler neck.
CAUTION: Use only the pressure cap specified for
this vehicle. Use of other pressure caps can lead to
coolant loss and overheating.
DIAGNOSIS AND TESTING - RADIATOR
PRESSURE CAP
Remove cap from radiator. Be sure that sealing
surfaces are clean. Moisten rubber gasket with water
and install the cap on pressure tester (tool 7700 or
an equivalent) (Fig. 11).Operate the tester pump and observe the gauge
pointer at its highest point. The cap release pressure
should be 124 to 145 kPa (18 to 21 psi). The cap is
satisfactory when the pressure holds steady. It is also
good if it holds pressure within the 124 to 145 kPa
(18 to 21 psi) range for 30 seconds or more. If the
pointer drops quickly, replace the cap.
CAUTION: Radiator pressure testing tools are very
sensitive to small air leaks, which will not cause
cooling system problems. A pressure cap that does
not have a history of coolant loss should not be
replaced just because it leaks slowly when tested
with this tool. Add water to tool. Turn tool upside
down and recheck pressure cap to confirm that cap
needs replacement.
CLEANING
Clean the radiator pressure cap using a mild soap
and water only.
INSPECTION
Visually inspect the pressure valve gasket on the
cap. Replace cap if the gasket is swollen, torn or
worn. Inspect the area around radiator filler neck for
white deposits that indicate a leaking cap.
Fig. 10 PRESSURE CAP
1 - MAIN SPRING
2 - GASKET RETAINER
3 - STAINLESS STEEL SWIVEL TOP
4 - RUBBER SEALS
5 - SPRING LOADED VALVE
6 - COOLANT PRESSURE BOTTLE
7 - FILLER NECK
8 - OVERFLOW NIPPLEFig. 11 Pressure Testing Radiator Pressure Cap -
Typical
1 - PRESSURE CAP
2 - TYPICAL COOLING SYSTEM PRESSURE TESTER
KJENGINE 7 - 25