Chrysler Town & Country/Voyager, Dodge Caravan, Plymouth Voyager. Manual — part 183
on high mileage vehicles. The temperature gauge will
show this, Refer to diagnosis in this section.
REMOVAL
(1) Drain cooling system down below the thermostat
level . Refer to Draining Cooling System in this group.
(2) Remove thermostat housing bolts and housing
(Figs. 8, 9 and 10).
(3) Remove thermostat, discard gasket and clean
both gasket sealing surfaces.
INSTALLATION—2.5L ENGINE
Place a new gasket (dipped in clean water) on water
box surface, center thermostat in water box on gasket.
Place housing over gasket and thermostat, making
sure thermostat is in the thermostat housing. Bolt
housing to water box (Fig. 8 ). Tighten bolts to 28 N
Im
(250 in. lbs.). Refill cooling system (see Refilling
System).
INSTALLATION—3.0L ENGINE
Center thermostat in water box pocket. Check that
the flange is seated correctly in the countersunk por-
tion of the intake manifold water box (Figs. 9 and 10).
Install new gasket on water box. Install housing over
gasket and thermostat and tighten bolts to 12 N
Im
(133 in. lbs.).
INSTALLATION—3.3L
Place a new gasket (dipped in water) on the water
box surface, center thermostat into opening in the in-
Fig. 8 Thermostat, Housing, and Water Box—2.5L
Engine
Fig. 9 Thermostat, Housing, and Water Box—3.0L
Engine
Fig. 10 Thermostat Installed—3.0L Engine
Fig. 11 Thermostat, Housing and Waterbox—3.3L
Engine
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COOLING SYSTEM
7 - 13
take manifold. Place housing over gasket and thermo-
stat, making sure thermostat is in recess provided (Fig.
11). Bolt housing to intake manifold, tighten bolts to 28
N
Im (250 in. lbs.). Refill cooling system (see Refilling
System).
COOLANT
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. Then carry
this heat to the radiator where the tube/fin assemblies
of these components can give it up to the air.
PERFORMANCE
Performance is measurable. For heat transfer pure
water excels (Formula = 1 btu per minute for each
degree of temperature rise for each pound of water).
This formula is altered when necessary additives to
control boiling, freezing, and corrosion are added as
follows:
• Pure Water (1 btu) boils at 100°C (212°F) and
freezes at 0°C (32°F).
• 100 percent Glycol (.7 btu) can cause a hot engine
and detonation and will lower the freeze point to -22°C
(-8°F).
• 50/50 Glycol and Water (.82 btu) is the recommended
combination that provides a freeze point of -37°C(-
35°F). The radiator, water pump, engine water jacket,
radiator pressure cap, thermostat, temperature gauge,
sending unit and heater are all designed for 50/50
glycol.
Where required, a 56 percent glycol and 44 percent
water mixture will provide a freeze point of-59°C
(-50°F).
CAUTION: Richer mixtures cannot be measured with
field equipment that can lead to problems associated
with 100 percent glycol.
SELECTION AND ADDITIVES
The use of aluminum cylinder heads, intake mani-
folds, and water pumps requires special corrosion pro-
tection. Mopar Antifreeze, Prestone II, Peak or anti-
freeze containing Alugard 340-2, or their equivalent is
recommended for best engine cooling without corro-
sion. When mixed only to a freeze point of-37°C (-35°F)
to -59°C (-50°F). If it looses color or becomes contami-
nated, drain, flush, and replace with fresh properly
mixed solution.
SERVICE
Coolant should be changed at 52,500 miles or three
years, whichever occurs first, then every two years or
30,000 miles.
ROUTINE LEVEL CHECK
Do not remove radiator cap for routine coolant
level inspections.
The coolant reserve system provides a quick visual
method for determining the coolant level without re-
moving the radiator cap. Simply observe, with the
engine idling and warmed up to normal operating
temperature, that the level of the coolant in the reserve
tank (Fig. 15) is between the minimum and maximum
marks.
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 reserve tank. Use only
50/50 mix of ethylene glycol type antifreeze and water.
SERVICE COOLANT LEVEL
The cooling system is closed and designed to main-
tain coolant level to the top of the radiator.
When servicing requires a coolant level check in the
radiator, the engine must be off and not under pres-
sure. Drain several ounces of coolant from the radiator
drain cock while observing the Coolant Recovery Sys-
tem (CRS) Tank. Coolant level in the CRS tank should
drop slightly. Then remove the radiator cap. The radia-
tor should be full to the top. If not, and the coolant level
in the CRS tank is at the MIN mark there is an air leak
in the CRS system. Check hose or hose connections to
the CRS tank, radiator filler neck or the pressure cap
seal to the radiator filler neck for leaks.
LOW COOLANT LEVEL AERATION
Low coolant level in a cross flow radiator will equal-
ize in both tanks with engine off. With engine at
running operating temperature the high pressure inlet
tank runs full and the low pressure outlet tank drops.
If this level drops below the top of the transmission oil
cooler, air will be sucked into the water pump:
• Transmission oil will become hotter.
• High reading shown on the temperature gauge.
• Air in the coolant can cause loss of flow through the
heater.
• Exhaust gas leaks into the coolant also can cause the
same problems?
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 CRS tank by
thermal expansion of the coolant. It then escapes to the
atmosphere in the CRS tank and is replaced with solid
coolant on cool down.
7 - 14
COOLING SYSTEM
.
COOLING SYSTEM DRAIN, CLEAN FLUSH AND
REFILL
Drain, flush, and fill the cooling system at the
mileage or time intervals specified in the Maintenance
Schedule in this Group. If the solution is dirty or rusty
or contains a considerable amount of sediment, clean
and flush with a reliable cooling system cleaner. Care
should be taken in disposing of the used engine coolant
from your vehicle. Check governmental regulations for
disposal of used engine coolant.
DRAINING COOLING SYSTEM
To drain cooling system move temperature selector
for heater to full heat with engine running (to provide
vacuum for actuation). Without removing radiator
pressure cap and with system not under pres-
sure, Shut engine off and open draincock. The coolant
reserve tank (Fig. 15) should empty first, then remove
radiator pressure cap. (if not, see Testing Cooling
System for leaks). To vent 2.5L engine remove the plug
above thermostat housing (Fig. 12). To vent 3.3L en-
gine remove the engine temperature sending unit (Fig.
13).
Removal of a plug or other component is required
because these thermostats do not have an air vent and
prevents air flow through it. This allows the coolant to
drain from the engine block.
CLEANING
Drain cooling system (see: Draining Cooling Sys-
tem) and refill with clean water (see Refilling Cool-
ing System). Run engine with radiator cap installed
until upper radiator hose is hot. Stop engine and drain
water from system. If water is dirty, fill, run and drain
system again until water runs clear.
REVERSE FLUSHING
Reverse flushing of the cooling system, is the forcing
of water through the cooling system, using air pressure
in a direction opposite to that of the normal flow of
water. This is usually only necessary with very dirty
systems with some evidence of partial plugging.
RADIATOR
Drain cooling system and remove radiator hoses from
engine. Install suitable flushing gun in radiator lower
hose. Fill radiator with clean water and turn on air in
short blasts.
CAUTION: Internal radiator pressure must not exceed
138 kPa (20 psi) as damage to radiator may result.
Continue this procedure until water runs clear.
ENGINE
Drain radiator (see: Draining Cooling System)
and remove hoses from radiator. Remove engine ther-
mostat and reinstall thermostat housing. Install suit-
able flushing gun to thermostat housing hose. Turn on
water, and when engine is filled, turn on air, but no
higher than 138 kPa (20 psi) in short blasts. Allow
engine to fill between blasts of air. Continue this
procedure until water runs clean. Reinstall thermostat
using a new housing gasket. Fill cooling system (See
Refilling).
CHEMICAL CLEANING
One type of corrosion encountered with aluminum
cylinder heads is aluminum hydroxide deposits. Corro-
sion products are carried to the radiator and deposited
when cooled off. They appear as dark grey when wet
and white when dry. This corrosion can be removed
with a two part cleaner (oxalic acid and neutralizer)
available in auto parts outlets. Follow manufacturers
directions for use.
Fig. 12 Thermostat Housing Drain/Fill Plug—2.5L
Engine
Fig. 13 Engine Temperature Sending Unit 3.3L
Drain/Fill
.
COOLING SYSTEM
7 - 15
REFILLING
First clean system to remove old glycol, see Cooling
System Cleaning.
Fill system, using antifreeze described in Coolant.
Fill 50 of capacity with 100 glycol. Then complete
filling system with water. The 2.5L engine requires
venting by removal of the plug on top of the water box
(Fig. 12). The 3.3L Engine requires removal of the
Engine Temperature Sending Unit on the front of the
cylinder head (Fig. 13). When coolant reaches this hole;
• Install vent plug and tighten to 20 NIm (15 ft. lbs.)
for 2.5L Engines.
• Install Engine Temperature Sending Unit and
tighten to 7 N
Im (60 in. lbs.) for 3.3L Engines.
Continue filling system until full, this provides bet-
ter heater performance. Be careful not to spill cool-
ant on drive belts or the alternator.
Fill coolant reserve system to at least the MAX mark
with 50/50 solution. It may be necessary to add coolant
to the reserve tank 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.
TESTING SYSTEM FOR LEAKS
With engine not running, wipe the radiator filler
neck sealing seat clean. The radiator should be full.
Attach the Tester Radiator Pressure Tool to the
radiator, as shown in (Fig. 14) and apply 104 kPa (15
psi) pressure. If the pressure drops more than 2 psi in
2 minutes inspect all points for external leaks.
All hoses, radiator and heater, should be shaken
while at 104 kPa (15 psi) since some leaks occur only
while driving due to engine rock, etc.
If there are no external leaks, after the gauge dial
shows a drop in pressure, detach the tester. Start
engine and run the engine up to normal operating
temperature to open the thermostat and allow the
coolant to expand. Reattach the tester. If the needle on
the dial fluctuates it indicates a combustion leak,
usually a head gasket leak.
WARNING: WITH TOOL IN PLACE, PRESSURE WILL
BUILDS UP FAST. EXCESSIVE PRESSURE BUILT UP,
BY CONTINUOUS ENGINE OPERATION, MUST BE
RELEASED TO A SAFE PRESSURE POINT. NEVER
PERMIT PRESSURE TO EXCEED 138 kPa (20 PSI).
If the needle on the dial does not fluctuate, race the
engine a few times. If an abnormal amount of coolant
or steam emits from the tail pipe, it may indicate a
coolant leak caused by a faulty head gasket, cracked
engine block, or cracked cylinder head.
There may be internal leaks that can be determined
by removing the oil dip-stick. If water globules appear
intermixed with the oil it will indicate an internal leak
in the engine. If there is an internal leak, the engine
must be disassembled for repair.
COOLANT RECOVERY SYSTEM (CRS)
This system works with the radiator pressure cap to
use thermal expansion and contraction of the coolant to
keep the coolant free of trapped air. Provides a conve-
nient and safe method for checking coolant level and
adjusting level at atmospheric pressure without re-
moving the radiator pressure cap. It also provides some
reserve coolant to cover minor leaks and evaporation or
boiling losses. All vehicles are equipped with this
system and take various shapes and forms. (Fig. 15)
shows a typical system in the typical location.
Fig. 14 Pressure Testing Cooling System
Fig. 15 Typical Coolant Recovery System
7 - 16
COOLING SYSTEM
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