Chrysler 300M, Dodge Interpid. Manual — part 47

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - COOLING SYSTEM

CONDITION

POSSIBLE CAUSES

CORRECTION

TEMPERATURE GAUGE
READING IS INCONSISTENT
(FLUCTUATES, CYCLES OR IS
ERRATIC).

1. During cold weather operation
with the heater blower in the high
position, the gauge reading may
drop slightly. Fluctuation is also
influenced by loads, outside
temperature, and cycling of the air
conditioning system.

1. A normal condition. No correction is
necessary.

2. Temperature gauge or engine
sending unit sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.

2. Check operation of gauge and repair
if necessary. Refer to INSTRUMENT
PANEL AND SYSTEMS.

3. Gauge reading rises when
vehicle is brought to a stop after
heavy use (engine still running).

3. A normal condition. No correction is
necessary. Gauge reading should return
to normal range after vehicle is driven.

4. Gauge reading high after
restarting a warmed-up (hot)
engine.

4. A normal condition. No correction is
necessary. The gauge should return to
normal range after a few minutes of
engine operation.

5. Coolant level low (air will build
up in the cooling system causing
the thermostat to open late).

5. Check and correct coolant leaks.
Refer to Testing Cooling System for
Leaks in this section.

6. Cylinder head gasket leaking
allowing exhaust gas to enter
cooling system causing thermostat
to open late.

6. (a) Check for cylinder head gasket
leaks with a commercially available
block leak tester. Repair as necessary.

(b) Check for coolant in engine oil.
Inspect for white steam emitting from
exhaust system. Repair as necessary.

7. Water pump impeller loose on
shaft.

7. Check water pump and replace as
necessary. Refer to Water Pump
Removal in this section.

8. Air leak on the suction side of
water pump allows air to build up in
cooling system causing thermostat
to open late.

8. Locate leak and repair as necessary.

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 Pressure Cap in this
group. Replace cap as necessary.

2. Incorrect cap was installed.

2. Replace cap as necessary.

3. Incorrect coolant mixture.

3. Make sure a 50% by volume mixture
of coolant is used.

4. System overfilled.

4. Ensure cold coolant level is between
MIN and MAX marks on coolant bottle.

LH

COOLING

7 - 3

COOLING (Continued)

CONDITION

POSSIBLE CAUSES

CORRECTION

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 -
COOLING SYSTEM LEAK TESTING)

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 freeze point of the coolant.
(Refer to 7 - COOLING/ENGINE/
COOLANT - DIAGNOSIS AND
TESTING) Adjust the ethylene glycol to
water ratio as required.

3. Wrong 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
bottle system.

1. (a) Pressure cap relief valve stuck.
(Refer to 7 - COOLING/ENGINE/
RADIATOR PRESSURE CAP -
INSPECTION) Replace as necessary.

(b) Hose between the pressure and
overflow container is plugged. Clean
vent 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

ELECTRIC RADIATOR FAN
RUNS ALL THE TIME.

1. Fan relay, Powertrain Control
Module (PCM) or engine coolant
temperature sensor possibly
defective.

1. (Refer to Appropriate Diagnostic
Information) Repair as necessary.

2. Check for low coolant level.

2. Repair as necessary.

3. A/C pressure transducer
defective.

3. (Refer to Appropriate Diagnostic
Information) Repair as necessary.

NOISY RADIATOR FAN.

1. Fan blade loose.

1. Replace radiator fan assembly.
(Refer to 7 - COOLING/ENGINE/
RADIATOR FAN - REMOVAL)

2. Fan blade striking a surrounding
object.

2. Locate point of fan blade contact and
repair/replace as necessary.

3. Air obstructions at radiator or A/C
condenser.

3. Remove obstructions and/or clean
debris.

4. Electric fan motor defective.

4. Replace radiator fan assembly.
(Refer to 7 - COOLING/ENGINE/
RADIATOR FAN - REMOVAL)

7 - 4

COOLING

LH

COOLING (Continued)

CONDITION

POSSIBLE CAUSES

CORRECTION

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. (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. Has a diagnostic trouble code
(DTC) been set?

1. (Refer to Appropriate Diagnostic
Information) Repair as necessary.

2. Low Coolant level.

2. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING) Repair as
necessary.

3. Air Trapped in heater core.

3. Improper coolant fill procedure.
(Refer to 7 - COOLING - STANDARD
PROCEDURE)

4. Obstructions in heater hose
fitting at engine or at heater core.

4. Remove heater hoses at both ends
and check for obstructions. Repair as
necessary.

5. Heater hose kinked or
obstructed.

5. Locate kinked or obstructed area.
Repair as necessary.

6. Thermostat possibly stuck open.

6. (Refer to 7 - COOLING/ENGINE/
ENGINE COOLANT THERMOSTAT -
DIAGNOSIS AND TESTING)

7. Water pump is not pumping
coolant to heater core. When the
engine is fully warmed up, both
heater hoses should be hot to the
touch. If only one of the hoses is
hot, the water pump may not be
operating correctly.

7. (Refer to 7 - COOLING/ENGINE/
WATER PUMP - DIAGNOSIS AND
TESTING)

HEAT ODOR

1. Various heat shields are used at
certain driveline components. One
or more of these shields may be
missing.

1. Locate missing shields and replace
or repair as necessary.

2. Is the temperature gauge reading
above the normal range?

2. Refer to Temperature Gauge Reads
High in these Diagnosis Charts.

LH

COOLING

7 - 5

COOLING (Continued)

CONDITION

POSSIBLE CAUSES

CORRECTION

3. Radiator fan operating
incorrectly.

3. (Refer to 7 - COOLING/ENGINE/
RADIATOR FAN - DIAGNOSIS AND
TESTING) Repair as necessary.

4. Has undercoating been applied
to any unnecessary component?

4. Clean undercoating as necessary.

5. Engine may be running rich,
causing the catalytic converter to
overheat

5. (Refer to Appropriate Diagnostic
Information)

POOR DRIVEABILITY
(THERMOSTAT POSSIBLY
STUCK OPEN). GAUGE MAY
BE READING LOW.

1. For proper driveability, clean
vehicle emissions and prevention of
buildup of engine oil sludge, the
thermostat must be operating
properly. Has a diagnostic trouble
code been set?

1. (Refer to Appropriate Diagnostic
Information) Replace thermostat if
necessary

STEAM IS COMING FROM
FRONT OF VEHICLE NEAR
GRILL AREA WHEN WEATHER
IS WET, ENGINE WARMED UP
AND RUNNING WITH VEHICLE
STATIONARY, OR JUST SHUT
OFF. TEMPERATURE GAUGE
IS NORMAL.

1. During wet weather, moisture
(snow, ice, rain, or condensation)
on the radiator will evaporate when
the thermostat opens. The
thermostat opening allows heated
coolant into the radiator. When the
moisture contacts the hot radiator,
steam may be emitted. this usually
occurs in cold weather with no fan
or air flow to blow it away.

1. Occasional steam emitting from this
area is normal. No repair is necessary.

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 and
service according to maintenance
schedule. (Refer to LUBRICATION &
MAINTENANCE/MAINTENANCE
SCHEDULES - DESCRIPTION)

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.

DIAGNOSIS AND TESTING - COOLING SYSTEM
LEAK

With engine not running, wipe the coolant bottle

neck sealing seat clean.

Attach a radiator pressure tester to the coolant

bottle, as shown in (Fig. 2) 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 moved

while at 15 psi since some leaks occur while driving
due to engine rock, etc.

If the cooling system will not pressurize easily and

there is no coolant leaks, the cooling system is only
partially filled. (Refer to 7 - COOLING - STANDARD
PROCEDURE - COOLING SYSTEM FILL)

If there are no external leaks after the gauge dial

shows a drop in pressure, detach the tester. Start
engine and run the engine to normal operating tem-

7 - 6

COOLING

LH

COOLING (Continued)