pressure DODGE NEON 2000 Service Service Manual

cover and flywheel. Heat buildup caused by slippage
can bake the oil residue onto the components. This
glaze-like residue ranges in color from amber to
black.
GREASE CONTAMINATION
Grease contamination is usually a product of over-
lubrication. During clutch service, apply only a small
amount of grease to the input shaft splines. Excess
grease may be thrown off during operation, contami-
nating the disc.
ROAD SPLASH/WATER CONTAMINATION
Road splash contamination is usually caused by
driving the vehicle through deep water puddles.
Water can be forced into the clutch housing, causing
clutch components to become contaminated. Facing of
disc will absorb moisture and bond to the flywheel
and/or, pressure plate, if vehicle is allowed to stand
for some time before use. If this condition occurs,
replacement of clutch assembly may be required.
Drive the vehicle until normal clutch operating tem-
perature has been obtained. This will dry off disc
assembly, pressure plate, and flywheel.
CLEANING PRECAUTIONS
Condensation from steam vapors tend to accumu-
late on the internal clutch mechanism when the vehi-
cle is steam cleaned. Facing of disc will absorb
moisture and will bond to flywheel and/or pressure
plate, if vehicle is allowed to stand for some time
before use. If this condition occurs, it may require
replacement of clutch assembly. After cleaning, drive
the vehicle to its normal clutch operating tempera-
ture. This will dry off disc assembly, pressure plate,
and flywheel.
SPECIFICATIONS
TORQUE
DESCRIPTION TORQUE
Modular Clutch-to-Drive Plate Bolts..... 88N´m
(65 ft. lbs.)
Transaxle-to-Engine Mounting Bolts...... 95N´m
(70 ft. lbs.)
PLCLUTCH 6 - 13
CLEANING AND INSPECTION (Continued)

COOLING SYSTEM
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
COOLING SYSTEM........................1
COOLANT...............................2
COOLANT PERFORMANCE..................2
COOLANT RECOVERY SYSTEM..............3
ENGINE THERMOSTAT.....................3
RADIATOR..............................3
RADIATOR COOLING FAN MODULE...........3
COOLING SYSTEM PRESSURE CAP..........4
RADIATOR HOSES AND CLAMPS............5
WATER PUMP...........................5
AUTOMATIC TRANSMISSION OIL COOLER.....6
ACCESSORY DRIVE BELTS.................6
ENGINE BLOCK HEATER...................6
DIAGNOSIS AND TESTING
COOLING SYSTEM DIAGNOSIS..............7
ENGINE THERMOSTAT TESTING............14
ACCESSORY DRIVE BELT DIAGNOSIS........14
WATER PUMP DIAGNOSIS................15
COOLING SYSTEM FLOW CHECK...........15
ELECTRIC FAN MOTOR TEST...............15
COOLANT CONCENTRATION TESTING........15
TESTING COOLING SYSTEM FOR LEAKS.....15
PRESSURE CAP TO FILLER NECK SEAL
PRESSURE RELIEF CHECK...............16
PRESSURE TESTING COOLING SYSTEM
PRESSURE CAP.......................16
LOW COOLANT LEVEL AERATION...........17
DEAERATION...........................17
TEMPERATURE GAUGE INDICATION.........17
ENGINE BLOCK HEATER..................17
SERVICE PROCEDURES
COOLANT LEVEL CHECKÐROUTINE.........17COOLANTÐADDING ADDITIONAL...........18
COOLANT LEVELÐSERVICING.............18
COOLING SYSTEMÐDRAINING.............19
COOLING SYSTEMÐREFILLING............19
REMOVAL AND INSTALLATION
WATER PUMP..........................19
WATER PUMP INLET TUBE................20
ENGINE THERMOSTAT....................20
RADIATOR.............................21
RADIATOR DRAINCOCK...................22
COOLING FAN MODULE...................22
COOLANT RECOVERY CONTAINER..........23
ENGINE BLOCK HEATER..................24
ACCESSORY DRIVE BELTS................24
AUTOMATIC BELT TENSIONER & PULLEY....26
DISASSEMBLY AND ASSEMBLY
COOLING FAN MODULE...................26
CLEANING AND INSPECTION
WATER PUMP..........................28
ACCESSORY DRIVE BELT INSPECTION.......28
COOLING SYSTEM CAP...................28
COOLING SYSTEM CLEANING..............28
RADIATOR FLUSHING....................28
REVERSE FLUSHING.....................29
CHEMICAL CLEANING....................29
ADJUSTMENTS
BELT TENSION..........................29
SPECIFICATIONS
COOLING SYSTEM CAPACITY..............30
TORQUE SPECIFICATIONS.................30
SPECIAL TOOLS
COOLING..............................30
DESCRIPTION AND OPERATION
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 conditioning condenser and transmission
oil lines.
²When the Engine is cold: The thermostat is
closed and 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
and the cooling system has flow through the radiator,
engine, heater system, and bypass.
PLCOOLING SYSTEM 7 - 1

Coolant flow circuit for the 2.0L engine is shown in
(Fig. 1).
During any reassembly procedures all pipe fittings
in water jacket, and water box require cleaning and
application of thread sealant for entire length of
threads.
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 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.
COOLANT PERFORMANCE
Performance is measurable. For heat transfer pure
water excels (Formula = 1 btu per minute for eachdegree 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 (0.82 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, tem-
perature 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.SELECTION AND ADDITIVES
The use of aluminum cylinder heads, intake mani-
folds, and water pumps requires special corrosion
Fig. 1 Cooling System Operation
1 ± HEATER
2 ± HEAT UP
3 ± COOL DOWN
4 ± PRESSURE CAP
5 ± THERMOSTAT HOUSING6 ± WATER PUMP
7 ± ENGINE
8 ± COOLANT RECOVERY SYSTEM TANK
9 ± RADIATOR
7 - 2 COOLING SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

protection. MopartAntifreeze or the equivalent is
recommended for best engine cooling without corro-
sion. 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.
COOLANT RECOVERY SYSTEM
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 expansion
and contraction. Also, the system provides a conve-
nient and safe method for checking and adjusting the
coolant level at atmospheric pressure without remov-
ing the pressure cap. It also provides some reserve
coolant to compensate for minor leaks and evapora-
tion or boiling losses. All vehicles are equipped with
this system (Fig. 2).
Refer to Coolant Level Check, Deaeration, and
Pressure Cap sections for operation and service.
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.
The engine thermostat is a wax pellet driven,
reverse poppet choke type. It is designed to provide
the fastest warm up possible by preventing leakage
through it and to guarantee a minimum engine oper-
ating temperature of 88 to 93ÉC (192 to 199ÉF). Also,
the thermostat will automatically reach wide open, to
accommodate unrestricted flow to the radiator astemperature 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 temperatureÐnot the thermostat.
A thermostats primary purpose is to maintain
engine temperature in a range that will provide sat-
isfactory engine performance and emission levels
under all expected driving conditions. It also provides
hot water (coolant) for heater performance. It does
this by transferring heat from engine metal and
automatic transmission oil cooler (if equipped) to
coolant, moving this heated coolant to the heater core
and radiator, and then transferring this heat to the
ambient air.
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 coolant within operating temperatures.
The radiator functions as a heat exchanger, using
air flow across the exterior of the radiator tubes. This
heat is then transferred from the coolant and into
the passing air.
The radiator has an aluminum core with plastic
tanks. Although stronger than brass, plastic tanks
are subject to damage by impact. Always handle radi-
ator with care.
RADIATOR COOLING FAN MODULE
The radiator cooling fan is a single speed electric
motor driven fan. The fan module includes an electric
motor, fan blade, and a support shroud that is
attached to the radiator (Fig. 3).
Fig. 2 Coolant Recovery System
1 ± RECOVERY HOSE
2 ± ENGINE COOLANT RECOVERY CONTAINER
3 ± PRESSURE CAP
Fig. 3 Radiator Fan
1 ± SCREWS
2 ± LOWER MOUNTS
3 ± FAN MOTOR ELECTRICAL CONNECTOR
PLCOOLING SYSTEM 7 - 3
DESCRIPTION AND OPERATION (Continued)

Radiator cooling fan control operation is accomplished
two ways. The fan always runs when the air condition-
ing 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 sen-
sor which sends the message to the Powertrain Control
Module (PCM). The PCM turns on the fan through a
fan relay by grounding the relay's coil. The fan relay is
located in the Power Distribution Center (PDC) (Fig. 4).
Refer to the label beneath the PDC cover for location of
fan relay.
The PCM will actuate the fan relay whenever the A/C
clutch is engaged regardless of coolant temperature and
vehicle speed. If the A/C clutch is not engaged, the PCM
will actuate the fan relay when the coolant temperature
reaches approximately (97É C) 207É F and turns off the
fan relay when the coolant temperature drops to
approximately (94ÉC) 201É F. The fan relay is also
turned off when the vehicle speed is above approxi-
mately 100 Km/h (62 MPH). Refer to Group 8W, Wiring
Diagrams for circuity provided.
If the cooling fan is inoperative or a Diagnostic
Trouble Code (DTC) related to fan control has been
set, refer to the appropriate Powertrain Diagnostic
Manual for complete diagnostic procedures.
COOLING SYSTEM PRESSURE CAP
The cooling system pressure cap is located on the cool-
ant outlet housing near the front of the cylinder head.
The cooling system will operate at higher than atmo-
spheric pressure. The higher pressure raises the coolant
boiling point, allowing increased radiator cooling capac-
ity. The pressure cap will release cooling system pres-
sure in a range of 97±124 kPa (14±18 psi).
A vent valve located in the center of the cap allows
a small amount of 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 during system cool-down.If the valve is
stuck shut, the radiator hoses will collapse on
cool-down. Clean the vent valve (Fig. 5) 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.
Fig. 4 Power Distribution Center (PDC)
RADIATOR COOLING FAN OPERATION CHART
Cooling Fan Control
A/C Off
Fan On: 97É C (207É F)
Fan Off: 94É C (201É F)Vehicle Speed >
100 Km/h (62
MPH)
A/C On
Fan OnÐregardless of coolant temperature or vehicle
speed.
Fig. 5 Cooling System Pressure Cap
1 ± PRESSURE RATING
2 ± FILLER NECK SEAL
3 ± PRESSURE VALVE
4 ± VACUUM VENT VALVE (SHOWN IN SEALING POSITION)
7 - 4 COOLING SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

RADIATOR HOSES AND CLAMPS
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT 15 MINUTES BEFORE WORKING ON VEHI-
CLE. 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
CLAMP. 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 (Fig. 6).
The hose clamps are removed by using Special Tool
6094 or equivalent constant tension clamp pliers
(Fig. 7) to compress the hose clamp.
A hardened, cracked, swollen or restricted hose
should be replaced. Care should be taken not to dam-
age radiator inlet and outlet when removing hoses.
Radiator hoses should be routed without any kinks
and indexed as designed. The use of molded hoses is
recommended.Make sure hoses and connectors are clean and dry
before installation. Do not lubricate hoses when
installing.
Spring type hose clamps are used in all applica-
tions. If replacement is necessary, replace with the
original Mopartequipment spring type clamp.
WATER PUMP
The water pump has a diecast aluminum body and
housing with a stamped steel impeller. The water
pump bolts directly to the cylinder block and is
driven by the timing belt (Fig. 8). Cylinder block to
water pump sealing is provided by a rubber O-ring.
The water pump is the ªheartº of the cooling sys-
tem. It pumps the coolant through the engine block,
cylinder head, heater core, and radiator.
NOTE: The water pump on all models can be
replaced without discharging the air conditioning
system.
Fig. 6 Spring Clamp Size Location
1 ± SPRING CLAMP SIZE LOCATION
Fig. 7 Hose Clamp Tool
1 ± HOSE CLAMP TOOL 6094
2 ± HOSE CLAMP
Fig. 8 Water Pump
1 ± CYLINDER BLOCK
2 ± PUMP BODY
PLCOOLING SYSTEM 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
recovery/reserve container and the
radiator. Inspect the system for
leaks. Repair as necessary. Refer to
WARNINGS 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 recovery/reserve
container and radiator?4. Check for coolant leaks and
repair as necessary. Refer to
Checking Cooling System for Leaks
in this section.
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.
PLCOOLING SYSTEM 7 - 7

CONDITION POSSIBLE CAUSE CORRECTION
10. Air leak on the suction side of
water pump allows air to build up in
cooling system. This will cause the
thermostat to open late.10. Locate leak and repair as
necessary.
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
FLOWING INTO RECOVERY
CONTAINER. TEMPERATURE
GAUGE READING MAY BE ABOVE
NORMAL, BUT NOT HIGH.
COOLANT LEVEL MAY BE HIGH
IN RECOVERY CONTAINER.1. Pressure relief valve in radiator
cap is defective.1. Check condition of radiator cap
and seals. Refer to Radiator Cap in
this section. Replace as necessary.
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 Testing Cooling
System For Leaks in this section.
DETONATION OR PRE-IGNITION
(NOT CAUSED BY IGNITION
SYSTEM). GAUGE MAY OR MAY
NOT BE READING HIGH.1. Engine overheating. 1. Check reason for overheating
and repair as necessary.
2. Freeze point of coolant not
correct.2. Check the freeze point of the
coolant. Refer to Coolant
Concentration Testing in this
section. Adjust glycol-to-water ratio
as required.
HOSE OR HOSES COLLAPSE
WHEN ENGINE IS COOLING1. Vacuum created in cooling
system on engine cool-down is not
being relieved through coolant
recovery/reserve container system.1. (a) Radiator cap relief valve
stuck. Refer to Radiator Cap in this
section. Replace as necessary.
(b) Hose between coolant
recovery/reserve container and
radiator is kinked. Repair as
necessary.
(c) Vent at coolant recovery/reserve
container is plugged. Clean vent
and repair as necessary.
(d) Recovery/reserve container is
internally blocked or plugged. Check
for blockage and repair as
necessary.
ELECTRIC RADIATOR FAN
OPERATES ALL THE TIME.1. Fan relay, powertrain control
module (PCM) or engine coolant
temperature sensor defective.1. Refer to appropriate Powertrain
Diagnostic Procedures manual for
operation of the DRB scan tool.
Repair as necessary.
2. Check for low coolant level. 2. Repair as necessary.
7 - 10 COOLING SYSTEMPL
DIAGNOSIS AND TESTING (Continued)

ENGINE THERMOSTAT TESTING
The thermostat is operated by a wax filled con-
tainer (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.
The thermostat that opens too soon type failure
mode is included in the on-board diagnosis. Thecheck engine light will not be lit by an open too soon
condition. If it has failed open, a diagnostic trouble
code (DTC) will be set. Do not change a thermostat
for lack of heater performance or temperature gauge
position, unless a DTC is present. See Diagnosis for
other probable causes. 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 Diagnosis in this section.
ACCESSORY DRIVE BELT DIAGNOSIS
CONDITION POSSIBLE CAUSE CORRECTION
BELT SLIPPAGE 1. Belt slipping because of
insufficient tension.1. Retension generator belt.
Replace the power steering belt's
automatic belt tensioner.
2. Belt excessively glazed or
hardened from heat and excessive
slippage.2. Replace belt.
3. Incorrect belt. 3. Replace belt.
4. Driven component bearing
failure.4. Replace faulty component.
5. Belt or pulley subjected to
substance (belt dressing, oil,
ethylene glycol) that has reduced
friction.5. Replace belt and clean pulleys.
BELT NOISE (OBJECTIONABLE
SQUEAL, SQUEAK, OR RUMBLE)1. Belt slippage. 1. Retension generator belt, replace
belt, or automatic belt tensioner.
2. Foreign material imbedded in
belt.2. Replace belt.
3. Non-uniform belt. 3. Replace belt.
4. Misaligned pulley(s). 4. Align accessories.
5. Non-uniform groove or eccentric
pulley.5. Replace pulley(s).
6. Bearing noise. 6. Locate and repair.
BELT ROLLED OVER IN GROOVE
OR BELT JUMPS OFF1. Broken cord in belt. 1. Replace belt.
2. Belt tension too loose, or too
tight.2. Retension generator belt.
Replace the power steering belt's
automatic belt tensioner.
3. Misaligned pulleys. 3. Align accessories.
4. Non-uniform grooves or eccentric
pulley.4. Replace pulley(s).
5. Foreign object(s) in grooves. 5. Remove foreign objects in
groove.
7 - 14 COOLING SYSTEMPL
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 cooling system pressure cap.
(2) Remove a small amount of coolant from the
system.
(3) Start the engine and warm up until thermostat
opens.
(4) With the thermostat open and coolant level low,
visually inspect for coolant flow. If flow is present,
the water pump is pumping coolant through the sys-
tem.
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.
ELECTRIC FAN MOTOR TEST
Refer to Powertrain Diagnostic Manual for proce-
dure.
COOLANT CONCENTRATION TESTING
Coolant concentration should be checked when any
additional coolant was added to system or after a
coolant drain, flush and refill. The coolant mixture
offers optimum engine cooling and protection against
corrosion when mixed to a freeze point of -37ÉC
(-34ÉF) to -59ÉC (-50ÉF). The use of a hydrometer or a
refractometer can be used to test coolant concentra-
tion.
A hydrometer will test the amount of glycol in a
mixture by measuring the specific gravity of the mix-
ture. The higher the concentration of ethylene glycol,
the larger the number of balls that will float, andhigher the freeze protection (up to a maximum of
70% by volume glycol).
A refractometer will test the amount of glycol in a
coolant mixture by measuring the amount a beam of
light bends as it passes through the fluid.
Some coolant manufactures use other types of gly-
cols into their coolant formulations. Propylene glycol
is the most common new coolant. However, propylene
glycol based coolants do not provide the same freez-
ing protection and corrosion protection and is only
recommended for limited usage. Refer to appropriate
Technical Service Bulletin(s) regarding use of propy-
lene glycol based coolants.
CAUTION: Do not mix types of coolantÐcorrosion
protection will be severely reduced.
Because ethylene glycol and propylene glycol do
not have the same specific gravities, the use of a
hydrometer will be inaccurate. Therefore, Special
Tool 8286 refractometer, is recommended when test-
ing either ethylene or propylene glycol coolants.
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. 12) and apply 104 kPa (15 psi)
pressure. If the pressure drops more than 2 psi in 2
minutes, 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
Fig. 12 Pressure Testing Cooling SystemÐTypical
1 ± PRESSURE TESTER
PLCOOLING SYSTEM 7 - 15
DIAGNOSIS AND TESTING (Continued)