1999 DODGE NEON radiator cap

COOLING
CONTENTS
page page
GENERAL INFORMATION
ACCESSORY DRIVE BELTS................ 2
AUTOMATIC TRANSMISSION OIL COOLER.... 3
COOLANT RECOVERY SYSTEM (CRS)....... 2
COOLANT.............................. 3
COOLING SYSTEM PRESSURE CAP......... 3
COOLING SYSTEM....................... 1
ENGINE BLOCK HEATER.................. 3
ENGINE THERMOSTAT.................... 3
RADIATOR............................. 3
WATER PUMP.......................... 3
DESCRIPTION AND OPERATION
COOLANT PERFORMANCE................. 4
COOLING SYSTEM PRESSURE CAP......... 5
ENGINE BLOCK HEATER.................. 5
ENGINE THERMOSTAT.................... 4
RADIATOR HOSES AND CLAMPS........... 5
WATER PUMP.......................... 6
DIAGNOSIS AND TESTING
ACCESSORY DRIVEBELT DIAGNOSIS....... 13
COOLING SYSTEM DIAGNOSIS............. 7
COOLING SYSTEM FLOW CHECK.......... 14
DEAERATION.......................... 15
ELECTRIC FAN MOTOR TEST.............. 14
ENGINE THERMOSTAT TESTING........... 13
LOW COOLANT LEVEL AERATION.......... 15
PRESSURE CAP TO FILLER NECK SEAL
PRESSURE RELIEF CHECK.............. 15
PRESSURE TESTING COOLING SYSTEM
PRESSURE CAP...................... 15
RADIATOR FAN CONTROL................ 14
TEMPERATURE GAUGE INDICATION........ 16
TESTING COOLING SYSTEM FOR LEAKS.... 14WATER PUMP DIAGNOSIS............... 14
SERVICE PROCEDURES
COOLANT LEVEL CHECKÐROUTINE........ 16
COOLANT LEVELÐSERVICING............ 16
COOLANTÐADDING ADDITIONAL......... 16
COOLING SYSTEMÐDRAINING............ 16
COOLING SYSTEMÐREFILLING........... 17
REMOVAL AND INSTALLATION
ACCESSORY DRIVE BELTS............... 21
ENGINE BLOCK HEATER................. 21
ENGINE THERMOSTAT................... 18
RADIATOR DRAINCOCK.................. 20
RADIATOR FANS AND MOTOR............ 20
RADIATOR............................ 19
WATER PUMP INLET TUBE............... 18
WATER PUMP......................... 17
CLEANING AND INSPECTION
ACCESSORY DRIVE BELT INSPECTION...... 22
CHEMICAL CLEANING................... 23
CLEANING COOLING SYSTEM............. 22
COOLING SYSTEM CAP.................. 22
RADIATOR FLUSHING................... 23
REVERSE FLUSHING.................... 23
WATER PUMP......................... 21
ADJUSTMENTS
BELT TENSION GAUGE METHOD........... 24
PROPER BELT TENSION................. 23
SPECIFICATIONS
COOLING SYSTEM CAPACITY............. 24
TORQUE.............................. 24
SPECIAL TOOLS
COOLING............................. 24
GENERAL INFORMATION
COOLING SYSTEM
The cooling system consists of an engine cooling
module, thermostat, coolant, and a water pump to
circulate the coolant. The engine cooling module may
consist of a radiator, electric fan motor, fan, shroud,
coolant reserve system, transmission oil cooler, hoses,
clamps, air condition condenser and transmission oil lines.
²When the Engine is cold: The thermostat is
closed; the cooling system has no flow through the
radiator. The coolant flows through the engine,
heater system and bypass.
²When the Engine is warm: Thermostat is open;
the cooling system has flow through radiator, engine,
heater system and bypass.
Coolant flow circuit for the 2.0L engine is shown in
(Fig. 1).
PLCOOLING 7 - 1

During any reassembly procedures all pipe fittings
in water jacket, and waterbox require cleaning and
application of thread sealant for entire length of
threads.
ACCESSORY DRIVE BELTS
If the engine is equipped with power steering or air
conditioning, it will have 2 drive belts. One belt
drives the generator, the other drives the Power
Steering and Air Conditioning. (Fig. 2)
COOLANT RECOVERY SYSTEM (CRS)
This system works in conjunction with the radiator
pressure cap to utilize thermal expansion and con-
traction of the coolant to keep the coolant free of
trapped air. The system provides space for expansionand contraction, and a convenient safe method for
checking and adjusting the coolant level at atmo-
spheric pressure without removing the pressure cap.
It also provides some reserve coolant to compensate
for minor leaks and evaporation or boiling losses. All
vehicles are equipped with this system (Fig. 3).
See Coolant Level Check, Service Procedures.
Deaeration and Pressure Cap sections for operation
and service.
Fig. 1 Cooling System Operation
Fig. 2 Drive Belts
Fig. 3 Coolant Recovery System
7 - 2 COOLINGPL
GENERAL INFORMATION (Continued)

ENGINE THERMOSTAT
The engine thermostat is located on the front of
the engine (radiator side) in the thermostat housing/
engine outlet connector. The thermostat has an air
bleed (vent) located in the flange and a O-ring for
sealing incorporate on it. There is a relief in the ther-
mostat housing/outlet connector for the O-ring.
WATER PUMP
The water pump has a diecast aluminum body and
housing with a stamped steel impeller. The water
pump bolts directly to the block (Fig. 4). Cylinder
block to water pump sealing is provided by a rubber
O-ring. The water pump is driven by the timing belt.
Refer to Group 9, Engine section for component
removal to access the water pump.
NOTE: The water pump on all models can be
replaced without discharging the air conditioning
system.
COOLANT
The cooling system is designed around the coolant.
The coolant must accept heat from engine block
metal and in the cylinder head area near the exhaust
valves. Then coolant carries this heat to the radiator
where the tube/fin assemblies of these components
can give off the heat to the air.
MopartAntifreeze or the equivalent is recom-
mended for optimum cooling performance and corro-
sion protection when mixed to a freeze point of -37É C
(-35É F).
COOLANT REPLACEMENT
Refer to Group 0, Lubrication and Maintenance for
schedule.
COOLING SYSTEM PRESSURE CAP
The cooling system is equipped with a pressure cap
that releases pressure at some point within a range
of 97-124 kPa (14-18 psi) (Fig. 5).
The system will operate at higher than atmo-
spheric pressure, which raises the coolant boiling
point, allowing increased radiator cooling capacity.
AUTOMATIC TRANSMISSION OIL COOLER
Oil coolers are internal oil to coolant type, mounted
in the radiator lower tank (Fig. 6). Rubber oil lines
feed the oil cooler and the automatic transmission.
Use only approved transmission oil cooler hose. Since
these are molded to fit space available, molded hoses
are recommended. Tighten Oil Cooler Hose Clamps
to 2 N´m (18 in. lbs.).
RADIATOR
The radiator is a down-flow type (vertical tubes)
with design features that provide greater strength,
as well as sufficient heat transfer capabilities to keep
the engine satisfactorily cooled (Fig. 6).
ENGINE BLOCK HEATER
The engine block heater is available as an optional
accessory. The heater, operated by ordinary house
current (110 Volt A.C.) through a power cord and con-
nector behind the radiator grille, provides easier
engine starting and faster warm-up when vehicle is
operated in areas having extremely low tempera-
tures.
Fig. 4 Water Pump
Fig. 5 Cooling System Pressure Cap
PLCOOLING 7 - 3
GENERAL INFORMATION (Continued)

DESCRIPTION AND OPERATION
ENGINE THERMOSTAT
The engine cooling thermostats are wax pellet
driven, reverse poppet choke type. They are designed
to provide the fastest warm up possible by prevent-
ing leakage through them and to guarantee a mini-
mum engine operating temperature of 88 to 93ÉC
(192 to 199ÉF). They also automatically reach wide
open so they do not restrict flow to the radiator as
temperature of the coolant rises in hot weather to
around 104ÉC (220ÉF). Above this temperature the
coolant temperature is controlled by the radiator, fan,
and ambient temperature, not the thermostat.
Its primary purpose is to maintain engine temper-
ature in a range that will provide satisfactory engine
performance and emission levels under all expected
driving conditions. It also provides hot water (cool-
ant) for heater performance. It does this by transfer-
ring heat from engine metal and automatic
transmission oil cooler (if equipped) to coolant, mov-
ing this heated coolant to the heater core and radia-
tor, and then transferring this heat to the ambient
air.
COOLANT 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:
²Pure Water (1 btu) boils at 100ÉC (212ÉF) and
freezes at 0ÉC (32ÉF).
²100 Percent Glycol (.7 btu) can cause a hot
engine and detonation and will raise the freeze point
to 22ÉC (-8ÉF).
²50/50 Glycol and Water (.82 btu) is the recom-
mended combination that provides a freeze point of
-37ÉC(-35ÉF). The radiator, water pump, engine water
jacket, radiator pressure cap, thermostat, tempera-
ture 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 -59ÉC
(-50ÉF).
CAUTION: Richer mixtures cannot be measured
with field equipment which can lead to problems
associated with 100 percent glycol.
Fig. 6 Cooling Modules
7 - 4 COOLINGPL
GENERAL INFORMATION (Continued)

SELECTION AND ADDITIVES
The use of aluminum cylinder heads, intake mani-
folds DOHC, and water pumps requires special corro-
sion protection. MopartAntifreeze or the equivalent
is recommended for best engine cooling without cor-
rosion. When mixed only to a freeze point of -37ÉC
(-35ÉF) to -59ÉC (-50ÉF). If it looses color or becomes
contaminated, drain, flush, and replace with fresh
properly mixed solution.
COOLING SYSTEM PRESSURE CAP
The cooling system is equipped with a pressure cap
that releases built up 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 a vent valve in the center of the cap that
allows a small coolant flow from the coolant reserve
system (CRS) tank. This valve is spring loaded in the
closed position. However it must be free to open dur-
ing system cool-down.If the valve is stuck shut,
the radiator hoses will collapse on cool-down.
Clean the vent valve (Fig. 7) to ensure proper
sealing function.
There is a gasket in the cap that seals to the top of
the filler neck so that vacuum is maintained to draw
coolant back into the system from the coolant reserve
system (CRS) tank.
RADIATOR HOSES AND CLAMPS
WARNING: IF VEHICLE HAS BEEN RUN
RECENTLY, WAIT 15 MINUTES BEFORE WORKING
ON VEHICLE. RELIEVE PRESSURE BY PLACING A
SHOP TOWEL OVER THE CAP AND WITHOUT
PUSHING DOWN ROTATE IT COUNTERCLOCKWISE
TO THE FIRST STOP. ALLOW FLUIDS TO ESCAPE
THROUGH THE OVERFLOW TUBE AND WHEN THE
SYSTEM STOPS PUSHING OUT COOLANT AND
STEAM AND THE PRESSURE DROPS CONTINUE
SERVICE.
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
CLAM. ALWAYS WEAR SAFETY GLASSES WHEN
SERVICING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only a original equipment clamp
with matching number or letter.The hose clamps are removed by using Special Tool
6094 or equivalent constant tension clamp pliers
(Fig. 8) to compress hose clamp.
A hardened, cracked, swollen or restricted hose
should be replaced. Do not damage radiator inlet and
outlet when loosening hoses.
Radiator hoses should be routed without any kinks
and indexed as designed. The use of molded hoses is
recommended.
Spring type hose clamps are used in all applica-
tions. If replacement is necessary replace with the
original Mopartequipment spring type clamp.
ENGINE BLOCK HEATER
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.The power cord
must be secured in its retainer clips, and not
positioned so it could contact linkages or
exhaust manifolds and become damaged.
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.
Fig. 7 Cooling System Pressure Cap
PLCOOLING 7 - 5
DESCRIPTION AND OPERATION (Continued)

DIAGNOSIS AND TESTING
COOLING SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSE CORRECTION
TEMPERATURE GAUGE READS
LOW1. Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open engine thermostat?1. Refer to On Board Diagnostic in
Group 25. Replace thermostat if
necessary. If a (DTC) has not been
set, the problem may be with the
temperature gauge.
2. Is the temperature gauge (if
equipped) connected to the
temperature gauge coolant sensor
on the engine?2. Check the connector at the
engine coolant sensor. Refer to
Group 8E. Repair as necessary.
3. Is the temperature gauge (if
equipped) operating OK?3. Check Gauge operation. Refer to
Group 8E. Repair as necessary.
4. Coolant level low during cold
ambient temperature, accompanied
by poor heater performance.4. Check coolant level in the coolant
overflow/reserve tank and the
radiator. Inspect the system for
leaks. Repair as necessary. Refer to
WARNINGS outlined in this section
before removing pressure cap.
TEMPERATURE GAUGE READS
HIGH OR ENGINE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST FROM SYSTEM.1. Trailer being towed, a steep hill
being climbed, vehicle being
operated in slow moving traffic, or
engine idling during high ambient
(outside) temperatures with air
conditioning on. High altitudes
Could aggravate these conditions.1. This may be a temporary
condition and repair is not
necessary. Turn off the air
conditioning and drive the vehicle
without any of the previous
conditions. Observe the temperature
gauge the gauge should return to
the normal range. If the gauge does
not return to the normal range,
determine the cause of the
overheating and repair. Refer to
POSSIBLE CAUSES in this section.
2. Is temperature gauge (if
equipped) reading correctly?2. Check gauge. Refer to Group 8E.
Repair as necessary.
3. Is temperature warning lamp (if
equipped) illuminating
unnecessarily?3. Check warning lamp operation.
Refer to Group 8E. Repair as
necessary.
4. Coolant low in overflow/reserve
tank and radiator?4. Check for coolant leaks and
repair as necessary. Refer to
checking cooling system for leaks in
this group.
5. Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following step 6.5. Tighten cap.
6. Poor seals at radiator cap. 6. (a) Check condition of cap and
cap seals. Refer to Radiator cap
Inspection. Replace cap if
necessary.
6. (b) Check condition of filler neck.
If neck is bent or damaged, replace
neck.
PLCOOLING 7 - 7

COOLING SYSTEM DIAGNOSIS CONT.
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READS
HIGH OR ENGINE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST FROM SYSTEM.7. Coolant level low in radiator but
not in coolant overflow/reserve
tank. This means the radiator is not
drawing coolant from the coolant
overflow/reserve tank as the engine
cools.
As the engine cools, a vacuum is
formed inside the cooling system. If
the radiator cap seals are defective,
or the cooling system has a leak, a
vacuum can not be formed.7. (a) Check condition of radiator
cap and cap seals. Replace cap if
necessary.
(b) Check condition of filler neck. If
neck is damaged, replace filler
neck.
(c) Check condition of hoses from
filler neck to coolant tank. It should
be tight at both ends without any
kinks or tears. Replace hose if
necessary.
(d) Check coolant overflow/reserve
tank and tank hoses for blockage.
Repair as necessary.
8. Freeze point of coolant not
correct. Mixture may be to rich.8. Check coolant. Refer to coolant
section in this group. Adjust glycol
to water ratio as required.
9. Coolant not flowing through
system.9. Check for coolant flow at filler
neck with some coolant removed,
engine warm and thermostat open.
Coolant should be observed flowing
through filler neck. If flow is not
observed determine reason for lack
of flow and repair as necessary.
10. Radiator or A/C condenser fins
are dirty or clogged.10. Clean insects or debris.
11. Radiator core is plugged or
corroded.11. Replace or re-core radiator.
12. Fuel or ignition system
problems.12. Refer to Fuel and Ignition
System group for diagnosis. Also
refer to the appropriate Powertrain
Diagnosis Procedures manual for
operation of the DRB scan tool.
13. Dragging brakes. 13. Inspect brake system and repair
as necessary. Refer to Group 5,
Brakes for diagnosis.
14. Bug screen is being used
causing reduced air flow.14. Remove bug screen.
15. Thermostat partially or
completely shut. This is more
prevalent on high mileage vehicles.15. Check thermostat operation and
replace as necessary. Refer to
thermostats in this group.
16. Electric cooling fan not
operating properly.16. Check electric fan operation and
repair as necessary.
17. Cylinder head gasket leaking. 17. Check cylinder head gasket for
leaks. Refer to testing cooling
system for leaks. For repairs, refer
to group 9, Engines.
18. Heater core leaking. 18. Check heater core for leaks.
Refer to Group 24, Heating and Air
Conditioning. Repair as necessary.
7 - 8 COOLINGPL
DIAGNOSIS AND TESTING (Continued)

WATER PUMP DIAGNOSIS
A quick flow test to tell whether or not the pump is
working is to see if the heater warms properly. A
defective pump will not be able to circulate heated
coolant through the long heater hose.
Another flow test to help determine pump opera-
tion.
WARNING: DO NOT remove radiator cap if the cool-
ing system is hot or under pressure.
(1) Remove radiator cap.
(2) Remove a small amount of coolant from the
system, start the engine and warm up until thermo-
stat opens. With the thermostat open and coolant
level low you will see if the water pump is pumping
coolant through the system.
COOLING SYSTEM FLOW CHECK
To determine whether coolant is flowing through
the cooling system, use the following procedures:
(1) If engine is cold, idle engine until normal oper-
ating temperature is reached. Then feel the upper
radiator hose. If it is hot, coolant is circulating.
WARNING: DO NOT REMOVE THE COOLING SYS-
TEM PRESSURE CAP WITH THE SYSTEM HOT AND
UNDER PRESSURE BECAUSE SERIOUS BURNS
FROM COOLANT CAN OCCUR.
(2) Remove pressure cap when engine is cold,
remove small amount of coolant Idle engine until
thermostat opens, you should observe coolant flow
while looking down the filler neck. Once flow is
detected install the pressure cap.
RADIATOR FAN CONTROL
Fan control is accomplished two ways. The fan
always runs when the air conditioning compressor
clutch is engaged. In addition to this control, the fan
is turned on by the temperature of the coolant which
is sensed by the coolant temperature sensor which
sends the message to the Powertrain Control Module
(PCM). The (PCM) turns on the fan through the
Solid State Fan Relay. The Solid State Fan Relay is
located on the left front inner frame just behind the
radiator. See Wiring Diagrams Manual for circuity
and diagnostics provided.
Switching through the (PCM) provides fan control
for the following conditions.
²The fan will not run during cranking until the
engine starts no matter what the coolant tempera-
ture is.
²Fan will run when the air conditioning clutch is
engaged and low pressure cutout switch is closed.
²Fan will run at vehicle speeds above about 40
mph only if coolant temperature reaches 110ÉC(230ÉF). It will turn off when the temperature drops
to 104ÉC (220ÉF). At speeds below 40 mph the fan
switches on at 102ÉC (215ÉF) and off at 93ÉC (200ÉF).
Refer to Radiator Fan Control Module Group 14,
Fuel Injection for more information.
ELECTRIC FAN MOTOR TEST
Refer to Powertrain Diagnostic Manual for procedure.
TESTING COOLING SYSTEM FOR LEAKS
The system should be full. With the engine not
running, wipe the filler neck sealing seat clean.
Attach a radiator pressure tester to the filler neck,
as shown in (Fig. 9) and apply 104 kPa (15 psi) pres-
sure. If the pressure drops more than 2 psi in 2 min-
utes, inspect the system for external leaks.
Move all hoses at the radiator and heater while
system is pressurize at 15 psi, since some leaks occur
due to engine rock while driving.
If there are no external leaks after the gauge dial
shows a drop in pressure, detach the tester. Start the
engine, and run the engine to normal operating tem-
perature in order to open the thermostat and allow
the coolant to expand. Reattach the tester. If the nee-
dle on the dial fluctuates it indicates a combustion
leak, usually a head gasket leak.
WARNING: WITH THE PRESSURE TESTER IN
PLACE PRESSURE BUILDS UP QUICKLY. ANY
EXCESSIVE PRESSURE BUILD-UP DUE TO CON-
TINUOUS 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 is emitted from the tail pipe, it may
indicate a faulty head gasket, cracked engine block,
or cracked cylinder head.
Fig. 9 Pressure Testing Cooling SystemÐTypical
7 - 14 COOLINGPL
DIAGNOSIS AND TESTING (Continued)