coolant level CHRYSLER CARAVAN 2003 User Guide

²Corrosion in the cooling system.
²Water pump seal may run dry, increasing the
risk of premature seal failure.
²Combustion gas leaks into the coolant can also
cause the above problems.
DIAGNOSIS AND TESTING - COOLING SYSTEM
DEAERATION
Air can only be removed from the system by gather-
ing under the pressure cap. On the next heat up it will
be pushed past the pressure cap into the coolant recov-
ery bottle by thermal expansion of the coolant. It then
escapes to the atmosphere in the coolant recovery bottle
and is replaced with coolant on cool down.
To effectively deaerate the system, multiple ther-
mal cycles of the system may be required.
NOTE: Deaeration does not occur at engine idleÐ
higher engine speeds are required. Normal driving
will deaerate cooling system.
STANDARD PROCEDURE
STANDARD PROCEDURE - COOLING SYSTEM
DRAINING
WARNING: DO NOT REMOVE OR LOOSEN THE
COOLANT PRESSURE CAP, CYLINDER BLOCK
DRAIN PLUGS, OR THE DRAINCOCK WHEN THESYSTEM IS HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
(1)Without removing radiator pressure cap
and with system not under pressure, open the
draincock. The draincock is located on the lower left
side of radiator (Fig. 5).
(2) After the coolant recovery/reserve container is
empty, then remove coolant pressure cap (Fig. 6).
(3) Remove the cylinder block drain plug(s).
Fig. 6 Cooling System Service Locations
1 - COOLANT RECOVERY CONTAINER 3 - ENGINE OIL LEVEL DIPSTICK
2 - ENGINE OIL FILL CAP 4 - RADIATOR PRESSURE CAP
Fig. 5 Draincock Location
1 - LEFT SIDE FRAME RAIL
2 - DRAINCOCK
7 - 4 COOLINGRS
COOLING (Continued)
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STANDARD PROCEDURE - COOLING SYSTEM
FILLING
Remove radiator pressure cap (Fig. 6) and fill sys-
tem, using a 50/50 mix of MopartAntifreeze/Coolant,
5 Year/100,000 Mile Formula and distilled water.
Continue filling system until full.Be careful not
to spill coolant on drive belts or the generator.
For cooling system capacity, (Refer to LUBRICATION
& MAINTENANCE/FLUID CAPACITIES - SPECIFI-
CATIONS).
Fill coolant recovery/reserve container (Fig. 6) to at
least the MAX mark with 50/50 solution. It may be
necessary to add coolant to the recovery/reserve con-
tainer after three or four warm up/cool down cycles
to maintain coolant level between the MAX and MIN
mark. This will allow trapped air to be removed from
the system.
STANDARD PROCEDURE - ADDING
ADDITIONAL COOLANT
The radiator cap should not be removed.
When additional coolant is needed to maintain this
level, it should be added to the coolant recovery/re-
serve container (Fig. 6). Use only 50/50 mix of ethyl-
ene glycol type antifreeze and distilled water. For the
recommeded antifreeze/coolant type (Refer to LUBRI-
CATION & MAINTENANCE/FLUID TYPES -
DESCRIPTION).
CAUTION: Do not use well water, or suspect water
supply in cooling system. A 50/50 ethylene glycol
and distilled water mix is recommended. For the
recommeded antifreeze/coolant type (Refer to
LUBRICATION & MAINTENANCE/FLUID TYPES -
DESCRIPTION).
STANDARD PROCEDURE - COOLANT LEVEL
CHECK
NOTE: Do not remove radiator cap for routine cool-
ant level inspections.
The coolant reserve system provides a quick visual
method for determining the coolant level without
removing the radiator cap.With the engine cold
and not running,simply observe the level of the
coolant in the recovery/reserve container (Fig. 6). The
coolant level should be between the MIN and MAX
marks.
SPECIFICATIONS
ACCESSORY DRIVE BELT TENSION
ACCESSORY DRIVE BELT TENSION
2.4L ENGINE
Air Conditioning
Compressor/GeneratorDynamic Tensioner
Power
SteeringNew Belt534 - 756 N
(120 - 170 lbs.)
Used Belt*356 - 534 N
(80 - 120 lbs)
*Belt is considered used after 15 minutes of run-in
time
3.3/3.8L ENGINES
Air Conditioning Compressor
Dynamic Tensioner
Generator/Water Pump/
Power Steering
TORQUE
DESCRIPTION N´mFt.
Lbs.In.
Lbs.
Accessory Drive Belt Tensioner
Assembly (3.3/3.8L)ÐBolt28 Ð 250
Engine Coolant Temperature
Sensor
(2.4 & 3.3/3.8L) 7 Ð 60
Generator & A/C Compressor
Drive Belt Tensioner Assembly
(2.4L)ÐBolt54 40 Ð
Coolant Outlet Connector/
Thermostat Housing
(2.4 & 3.3/3.8L)ÐBolts 28 Ð 250
Water Pump
(2.4 & 3.3/3.8L)ÐBolts 12 Ð 105
Water Pump Inlet Tube
(2.4L)ÐBolts12 Ð 105
Water Pump Inlet Tube
(3.3/3.8L)ÐBolts28 Ð 250
Water Pump Pulley (3.3/3.8L)Ð
Bolts28 Ð 250
Radiator to A/C CondenserÐ
Screws5Ð45
Radiator FanÐScrews 5 Ð 45
Radiator Mounting (Upper
Bracket)ÐNuts12 Ð 105
RSCOOLING7-5
COOLING (Continued)
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ENGINE
DIAGNOSIS AND TESTING - ENGINE COOLING
SYSTEM
Establish what driving condition caused the cooling
system complaint. The problem may be caused by an
abnormal load on the system such as the following:
prolonged idle, very high ambient temperature, slight
tail wind at idle, slow traffic speed, traffic jam, high
speed, steep grade.
DRIVING TECHNIQUES
To avoid overheating the cooling system:
(1) Idle with A/C off when temperature gauge is at
end of normal range.
(2) Do not increase engine speed for more air flow
and coolant flow because the electric motor fan sys-
tems are not responsive to engine RPM. The added
cooling from higher coolant flow rate is more than
offset by increased heat rejection (engine heat added
to coolant).
TRAILER TOWING
Consult the owner's manual under Trailer Towing
and do not exceed specified limits.
VISUAL INSPECTION
If the cooling system problem is not caused by a
driving condition, perform a visual inspection to
determine if there was a recent service or accident
repair, including the following:
²Loose/damaged water pump drive belt
²Incorrect cooling system refilling (trapped air or
low level)
²Brakes possibly dragging
²Damaged hoses
²Loose/damaged hose clamps
²Damaged/incorrect engine thermostat
²Damaged cooling fan motor, fan blade and fan
shroud
²Damaged head gasket
²Damaged water pump
²Damaged radiator
²Damaged coolant recovery system
²Damaged heater core
²Open/shorted electrical circuits
If the visual inspection reveals none of the above
as cause for a cooling system complaint, refer to the
following diagnostic charts.
COOLING SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT
NOT HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT RESERVE/
OVERFLOW TANK.1. Pressure relief valve in radiator
cap is defective, or was not
properly seated.1. Check condition of radiator cap
and cap seal. (Refer to 7 -
COOLING/ENGINE/RADIATOR
PRESSURE CAP - DIAGNOSIS
AND TESTING) Replace cap as
necessary.
2. Incorrect cap was installed. 2. Replace cap as necessary.
3. Incorrect coolant mixture. 3. Check concentration level of the
coolant. (Refer to 7 - COOLING/
ENGINE/COOLANT - DIAGNOSIS
AND TESTING) Adjust the ethylene
glycol-to-water ratio as required.
COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE IS
READING HIGH OR HOT.1. Coolant leaks in radiator, cooling
system hoses, water pump or
engine.1. Pressure test and repair as
necessary. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING)
7 - 14 ENGINERS
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CONDITION POSSIBLE CAUSES CORRECTION
DETONATION OR PRE-IGNITION
(NOT CAUSED BY IGNITION
SYSTEM). GAUGE MAY NOT BE
READING HIGH.1. Engine overheating. 1. Check reason for overheating
and repair as necessary.
2. Freeze point of coolant not
correct. Mixture too concentrated or
too diluted.2. Check concentration level of the
coolant. (Refer to 7 - COOLING/
ENGINE/COOLANT - DIAGNOSIS
AND TESTING) Adjust the ethylene
glycol-to-water ratio as required.
3. Incorrect cooling system
pressure cap.3. Install correct pressure cap.
HOSE(S) COLLAPSE AS ENGINE
COOLS DOWN.1. Vacuum created in cooling
system on engine cool-down is not
being relieved through coolant
recovery system.1. (a) Pressure cap relief valve
stuck. (Refer to 7 - COOLING/
ENGINE/RADIATOR PRESSURE
CAP - DIAGNOSIS AND TESTING)
Replace as necessary.
(b) Hose between the radiator and
overflow container is plugged or
pinched. Clean and repair as
necessary.
(c) Vent at coolant reserve/overflow
container is plugged. Clean vent
and repair as necessary.
(d) Reserve/overflow container is
internally blocked. Clean and repair
as necessary.
INADEQUATE AIR CONDITIONER
PERFORMANCE (COOLING
SYSTEM SUSPECTED).1. Radiator and/or A/C condenser is
restricted, obstructed, or dirty
(insects, leaves, etc.).1. Remove restriction and/or clean
as necessary.
2. Electrical radiator fan not
operating when A/C is operated.2. For test procedure (Refer to
appropriate Diagnostic Information).
Repair as necessary.
3. Engine is overheating (heat may
be transferred from radiator to A/C
condenser). High underhood
temperatures due to engine
overheating may also transfer heat
to A/C components.3. Correct overheating condition.
4. All models are equipped with air
seals at the radiator and/or A/C
condenser. If these seals are
missing or damaged, not enough
air flow will be pulled through the
radiator and A/C condenser.4. Check for missing or damaged air
seals and repair as necessary.
INADEQUATE HEATER
PERFORMANCE.1. Check for a Diagnostic trouble
code (DTC).1. For procedures, (Refer to
appropriate Diagnostic Information).
Repair as necessary.
2. Coolant level low. 2. (Refer to 7 - COOLING -
STANDARD PROCEDURE) Repair
as necessary.
RSENGINE7-15
ENGINE (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
COOLANT COLOR 1. Coolant color is not necessarily
an indication of adequate corrosion
or temperature protection. Do not
rely on coolant color for determining
condition of coolant.1. Check the freeze point of the
coolant. (Refer to 7 - COOLING/
ENGINE/COOLANT - DIAGNOSIS
AND TESTING) Adjust the ethylene
glycol-to-water ratio as necessary.
COOLANT LEVEL CHANGES IN
COOLANT BOTTLE.
TEMPERATURE GAUGE IS IN
NORMAL RANGE.1. Level changes are to be
expected as coolant volume
fluctuates with engine temperature.
The coolant level will also drop as
the system removes air from a
recent filling.1. A normal condition. No repair is
necessary.
Refer to (Fig. 1) when using the TEMPERATURE
GAUGE INDICATION DIAGNOSIS CHART.
TEMPERATURE GAUGE INDICATION DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC).1. Normal reaction to fan and/or
thermostat cycle (Fig. 1 ),
Examples B and C. During cold
weather operation with the heater
blower in the high position, the
gauge reading may drop slightly
(Fig. 1 ), Example D. Fluctuation is
also influenced by outside
temperature and heavy loads (Fig.
1 ), Example E.1. A normal condition. No correction
is necessary.
2. Gauge reading rises when
vehicle is brought to a stop after
heavy use (engine still running)
(Fig. 1 ), Example F.2. A normal condition. No correction
is necessary. Gauge reading should
return to normal range (Fig. 1 ),
Example A, after vehicle is driven.
3. Gauge reading high after
restarting a warmed-up (hot)
engine.3. A normal condition. No correction
is necessary. The gauge should
return to normal range (Fig. 1 ),
Example A, after a few minutes of
engine operation.
4. Temperature gauge or engine
coolant temperature sensor
defective or shorted. Also, corroded
or loose wiring in the electrical
circuit.4. Check operation of gauge or
engine coolant temperature sensor
and repair, if necessary.
RSENGINE7-17
ENGINE (Continued)
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for checking coolant level and adjusting level at
atmospheric pressure without removing the radiator
pressure cap. It also provides some reserve coolant to
cover deaeration, evaporation, or boiling losses.
DIAGNOSIS AND TESTING - COOLANT
RECOVERY SYSTEM
The cooling system is closed and designed to main-
tain coolant level to the top of the radiator.
(1) With the engineoffand cooling systemnot
under pressure, drain several ounces of coolant from
the radiator draincock while observing the coolant
recovery container. Coolant level in the container
should drop.
(2) Remove the radiator pressure cap. The coolant
level should be full to the top radiator neck. If not,
and the coolant level in the container is at or above
the MIN mark, there is an air leak in the coolant
recovery system.
(3) Check hose and hose connections to the con-
tainer, radiator filler neck or the pressure cap seal to
the radiator filler neck for leaks.
REMOVAL
(1) Raise the vehicle on hoist.
(2) Remove the lower attaching screws (Fig. 2).
(3) Lower the vehicle.
(4) Remove the upper attaching screw (Fig. 2).
(5) Disconnect recovery hose from container (Fig.
2).
(6) Remove the recovery container.
INSTALLATION
(1) Connect the recovery hose to container (Fig. 2).
(2) Position the recovery container on the frame
rail (Fig. 2).
(3) Install the upper attaching screw and tighten
to 7 N´m (60 in. lbs.) (Fig. 2).
(4) Raise the vehicle on hoist.
(5) Install the lower attaching screws and tighten
to 8.5 N´m (75 in. lbs.) (Fig. 2).
(6) Lower the vehicle.
(7) Add coolant to container as necessary. (Refer to
7 - COOLING - STANDARD PROCEDURE)
ENGINE BLOCK HEATER
DESCRIPTION
The engine block heater is available as an optional
accessory on all models. The heater is operated by
ordinary house current (110 Volt A.C.) through a
power cord located behind the radiator grille. This
provides easier engine starting and faster warm-up
when vehicle is operated in areas having extremely
low temperatures. The heater is mounted in a core
hole (in place of a core hole plug) in the engine block,
with the heating element immersed in coolant.
OPERATION
The block heater element is submerged in the cool-
ing system's coolant. When electrical power (110 volt
A.C.) is applied to the element, it creates heat. This
heat is transferred to the engine coolant. This pro-
vides easier engine starting and faster warm-up
when vehicle is operated in areas having extremely
low temperatures.
DIAGNOSIS AND TESTING - ENGINE BLOCK
HEATER TESTING
If unit does not operate, trouble can be in either
the power cord or the heater element. Test power
cord for continuity with a 110-volt voltmeter or 110-
volt test light; test heater element continuity with an
ohmmeter or 12-volt test light.
REMOVAL
(1) Drain coolant from radiator and cylinder block.
(Refer to 7 - COOLING - STANDARD PROCEDURE)
(2) Disconnect the power cord plug from heater.
(3) Loosen screw in center of heater. Remove the
heater assembly.
INSTALLATION
(1) Clean block core hole and heater seat.
(2) Insert heater assembly with element loop posi-
tionedupward.
Fig. 2 Coolant Recovery Container
1 - UPPER BOLT ATTACHING TO BATTERY TRAY
2 - COOLANT RECOVERY CONTAINER
3 - UPPER BOLT
4 - HOSE
5 - LOWER BOLT (QTY. 2)
6 - LEFT SIDE FRAME RAIL
7 - 20 ENGINERS
COOLANT RECOVERY CONTAINER (Continued)
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(3) With heater seated, tighten center screw
securely to assure a positive seal.
(4) Install power cord plug to heater.
(5) Fill cooling system with coolant to the proper
level. (Refer to 7 - COOLING - STANDARD PROCE-
DURE)
ENGINE COOLANT
TEMPERATURE SENSOR - 2.4L
DESCRIPTION
The engine coolant temperature sensor threads
into the top of the thermostat housing (Fig. 3). New
sensors have sealant applied to the threads.
REMOVAL
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Drain the cooling system below thermostat
level. (Refer to 7 - COOLING - STANDARD PROCE-
DURE)
(2) Disconnect coolant temperature sensor electri-
cal connector.
(3) Remove coolant temperature sensor (Fig. 3).
INSTALLATION
(1) Install coolant temperature sensor (Fig. 3).
Tighten sensor to 7 N´m (60 in. lbs.).
(2) Connect electrical connector to sensor.
(3) Fill cooling system. (Refer to 7 - COOLING -
STANDARD PROCEDURE)
ENGINE COOLANT
TEMPERATURE SENSOR -
3.3/3.8L
DESCRIPTION
The engine coolant temperature sensor threads
into a coolant passage on lower intake manifold near
the thermostat (Fig. 6). New sensors have sealant
applied to the threads.
REMOVAL
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Drain cooling system below engine coolant tem-
perature sensor level. (Refer to 7 - COOLING -
STANDARD PROCEDURE)
(2) Remove power steering reservoir and relocate
(Fig. 4). Do not disconnect hoses.
Fig. 3 Engine Coolant Temperature Sensor - 2.4L
1 - MAP SENSOR
2 - COOLANT TEMPERATURE SENSORFig. 4 Power Steering Fluid Reservoir
1 - POWER STEERING RESERVOIR
2 - BOLT - RESERVOIR TO MANIFOLD
3 - NUT - RESERVOIR TO COIL BRACKET
RSENGINE7-21
ENGINE BLOCK HEATER (Continued)
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DIAGNOSIS AND TESTING - ENGINE COOLANT
THERMOSTAT
The thermostat is operated by a wax filled cham-
ber (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.
Thermostat diagnostics is included in powertrain
control module's (PCM) programing for on-board
diagnosis. The malfunction indicator light (MIL) will
illuminate and a diagnostic trouble code (DTC) will
be set when an ªopen too soonº condition occurs. Do
not change a thermostat for lack of heater perfor-
mance or temperature gauge position, unless a DTC
is present. For other probable causes, (Refer to 7 -
COOLING/ENGINE - DIAGNOSIS 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).
ENGINE COOLANT
THERMOSTAT - 2.4L
REMOVAL
(1) Drain cooling system below the thermostat
level. (Refer to 7 - COOLING - STANDARD PROCE-
DURE)
(2) Remove radiator upper hose from the coolant
outlet housing (Fig. 7).
(3) Remove coolant outlet housing bolts and hous-
ing (Fig. 8).
(4) Remove thermostat. Discard gasket and clean
both gasket sealing surfaces.
INSTALLATION
(1) Place a new gasket (dipped in clean water) on
the coolant outlet connector surface. Position thermo-
stat with air bleed at the 12 o'clock position in ther-
mostat housing (Fig. 8).
(2) Position the coolant outlet connector and gas-
ket over the thermostat, making sure thermostat is
seated in the thermostat housing.
(3) Position outlet connector to thermostat housing
and install bolts (Fig. 8). Tighten bolts to 28 N´m
(250 in. lbs.).
(4) Install the radiator upper hose to coolant outlet
housing (Fig. 7).
(5) Refill the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
ENGINE COOLANT
THERMOSTAT - 3.3/3.8L
REMOVAL
(1) Drain cooling system down below the thermo-
stat level. (Refer to 7 - COOLING - STANDARD
PROCEDURE)
(2) Remove radiator upper hose from coolant outlet
connector (Fig. 9).
Fig. 7 RADIATOR HOSES TO ENGINE - 2.4L
1 - UPPER HOSE
2 - LOWER HOSE
Fig. 8 Thermostat and Outlet Connector - 2.4L
Engine
1 - THERMOSTAT
2 - GASKET
3 - COOLANT OUTLET CONNECTOR
4 - BOLT
RSENGINE7-23
ENGINE COOLANT THERMOSTAT (Continued)
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(3) Position a new gasket over the thermostat and
connector making sure thermostat is in proper posi-
tion and in the recess provided.
(4) Install thermostat and connector assembly to
the intake manifold (Fig. 10). Tighten bolts to 28
N´m (250 in. lbs.).
(5) Install the radiator upper hose to coolant outlet
connector (Fig. 9).
(6) Refill the cooling system to the proper level.
(Refer to 7 - COOLING - STANDARD PROCEDURE)
RADIATOR
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove radiator upper crossmember support.
(Refer to 23 - BODY/EXTERIOR/GRILLE OPENING
REINFORCEMENT - REMOVAL)
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK PLUG OR THE RADIATOR DRAINCOCK
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
(3) Drain the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
(4) Remove the radiator fans. (Refer to 7 - COOL-
ING/ENGINE/RADIATOR FAN - REMOVAL)
(5) Disconnect coolant reserve/recovery hose.
(6) Remove vapor purge solenoid from mounting
bracket.
(7) Disconnect upper and lower hoses from the
radiator (Fig. 13) or (Fig. 14).(8) Remove the A/C condenser side brackets to
radiator attaching screws (Fig. 15). Separate the con-
denser from the radiator by lifting upward to disen-
gage from lower mounts (Fig. 15). Allow the
condenser to rest in front of radiator.
(9) Radiator can now be lifted free from engine
compartment.Care should be taken not to dam-
age radiator cooling fins or water tubes during
removal.
INSTALLATION
(1)Be sure the air seal is in position before
radiator is installed.Slide radiator down into posi-
tion. Seat the radiator with the rubber isolators into
the mounting holes provided, with a 10 lbs. force.
(2) Position air conditioning condenser onto the
radiator lower mounts and install upper screws (Fig.
15). Tighten fasteners to 5 N´m (45 in. lbs.).
(3) Install the radiator upper and lower hoses (Fig.
13) or (Fig. 14).
(4) Connect the coolant reserve/recovery hose.
(5) Connect the vapor purge solenoid to the mount-
ing bracket.
(6) Install the radiator fans. (Refer to 7 - COOL-
ING/ENGINE/RADIATOR FAN - INSTALLATION)
(7) Install the radiator upper crossmember sup-
port. (Refer to 23 - BODY/EXTERIOR/GRILLE
OPENING REINFORCEMENT - INSTALLATION)
(8) Fill the cooling system. (Refer to 7 - COOLING
- STANDARD PROCEDURE)
(9) Connect negative cable to battery.
Fig. 13 Radiator Hoses to Radiator - 2.4L
1 - UPPER HOSE
2 - LOWER HOSE
3 - HOSE SUPPORT CLIP
Fig. 14 Radiator Hoses to Radiator - 3.3/3.8L
1 - UPPER HOSE
2 - LOWER HOSE
RSENGINE7-25
ENGINE COOLANT THERMOSTAT - 3.3/3.8L (Continued)
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OPERATION
The cooling system is equipped with a pressure cap
that releases excessive pressure; maintaining a range
of 97-124 kPa (14-18 psi).
The cooling system will operate at higher than
atmospheric pressure. The higher pressure raises the
coolant boiling point thus, allowing increased radia-
tor cooling capacity.
There is also a vent valve in the center of the cap.
This valve also opens when coolant is cooling and
contracting, allowing the coolant to return to cooling
system from coolant reserve system tank by vacuum
through a connecting hose.If valve is stuck shut,
or the coolant recovery hose is pinched, the
radiator hoses will be collapsed on cool down.
Clean the vent valve (Fig. 17) and inspect cool-
ant recovery hose routing, to ensure proper
sealing when boiling point is reached.
The gasket in the cap seals the filler neck, so that
vacuum can be maintained, allowing coolant to be
drawn back into the radiator from the reserve tank.
If the gasket is dirty or damaged, a vacuum
may not be achieved, resulting is loss of coolant
and eventual overheating due to low coolant
level in radiator and engine.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - COOLING SYSTEM
PRESSURE CAP TESTING
Dip the pressure cap in water. Clean any deposits
off the vent valve or its seat and apply cap to end of
the Pressure Cap Test Adaptor that is included with
the Cooling System Tester 7700 (Fig. 18). Working
the plunger, bring the pressure to 104 kPa (15 psi) on
the gauge. If the pressure cap fails to hold pressure
of at least 97 kPa (14 psi), replace the pressure cap.
CAUTION: The Cooling System Tester Tool is very
sensitive to small air leaks that will not cause cool-
ing 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 the tool. Turn tool
upside down and recheck pressure cap to confirm
that cap is bad.
If the pressure cap tests properly while positioned
on Cooling System Tester (Fig. 18), but will not hold
pressure or vacuum when positioned on the filler
neck. Inspect the filler neck and cap top gasket for
irregularities that may prevent the cap from sealing
properly.
DIAGNOSIS AND TESTING - RADIATOR CAP
TO FILLER NECK SEAL
The pressure cap upper gasket (seal) pressure
relief can be checked by removing the overflow hose
at the radiator filler neck nipple (Fig. 19). Attach the
Radiator Pressure Tool to the filler neck nipple and
pump air into the radiator. Pressure cap upper gas-
ket should relieve at 69-124 kPa (10-18 psi) and hold
pressure at 55 kPa (8 psi) minimum.
Fig. 18 Testing Cooling System Pressure Cap
1 - PRESSURE CAP
2 - PRESSURE TESTER
Fig. 19 Radiator Pressure Cap Filler Neck
1 - OVERFLOW NIPPLE
2 - MAIN SPRING
3 - GASKET RETAINER
4 - STAINLESS-STEEL SWIVEL TOP
5 - RUBBER SEALS
6 - VENT VALVE
7 - RADIATOR
8 - FILLER NECK
RSENGINE7-27
RADIATOR PRESSURE CAP (Continued)
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