Dodge Durango (HB). Manual - part 129

CONDITION

POSSIBLE CAUSES

CORRECTION

TEMPERATURE GAUGE READING
IS INCONSISTANT (FLUCTUATES,
CYCLES, OR IS ERRATIC

1. During cold weather operation,
with the heater in the high position,
the gauge reading may drop
slightly.

1. During cold weather operation,
with the heater in the high position,
the gauge reading may drop slightly.

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

2. Check operation of gauge and
repair if necessary. (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING).

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 should return
to normal range after vehicle is
driven.

4. Gauge reading high after
re-starting 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 in radiator (air
will build up in the cooling system
causing the thermostat to open
late).

5. Check and correct coolant leaks.
(Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).

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

6. (a) Check for cylinder head
gasket leaks. (Refer to 7 -
COOLING - DIAGNOSIS AND
TESTING).

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

7. Water pump impeller loose on
shaft.

7. Check water pump and replace
as necessary. (Refer to 7 -
COOLING/ENGINE/WATER PUMP -
REMOVAL).

8. Loose accessory drive belt.
(water pump slipping)

8.. Check and correct as necessary.
(Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS
- DIAGNOSIS AND TESTING)

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

9. Locate leak and repair as
necessary.

PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
TO COOLANT TANK.
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.

1. Check condition of radiator cap
and cap seals. (Refer to 7 -
COOLING/ENGINE/RADIATOR
PRESSURE CAP - DIAGNOSIS
AND TESTING). Replace cap as
necessary.

COOLING

7 - 11

CONDITION

POSSIBLE CAUSES

CORRECTION

COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE 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).

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. Mixture is too rich or too
lean.

2. Check coolant concentration.
(Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
DESCRIPTION).

HOSE OR HOSES COLLAPSE
WHILE ENGINE IS RUNNING

1. Vacuum created in cooling
system on engine cool-down is not
being relieved through coolant
reserve/overflow system.

1. (a) Radiator cap relief valve
stuck. (Refer to 7 - COOLING/
ENGINE/RADIATOR PRESSURE
CAP - DIAGNOSIS AND TESTING)
. Replace if necessary

(b) Hose between coolant
reserve/overflow tank and radiator is
kinked. Repair as necessary.

(d) Reserve/overflow tank is
internally blocked or plugged. Check
for blockage and repair as
necessary.

NOISY VISCOUS FAN/DRIVE

1. Fan blades loose.

1. Replace fan blade assembly.
(Refer to 7 - COOLING/ENGINE/
FAN DRIVE VISCOUS CLUTCH -
REMOVAL).

2. Fan blades striking a surrounding
object.

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

3. Air obstructions at radiator or air
conditioning condenser.

3. Remove obstructions and/or
clean debris or insects from radiator
or A/C condenser.

4. Thermal viscous fan drive has
defective bearing.

4. Replace fan drive. Bearing is not
serviceable. (Refer to 7 - COOLING/
ENGINE/FAN DRIVE VISCOUS
CLUTCH - REMOVAL).

5. A certain amount of fan noise
may be evident on models
equipped with a thermal viscous fan
drive. Some of this noise is normal.

5. (Refer to 7 - COOLING/ENGINE/
FAN DRIVE VISCOUS CLUTCH -
DESCRIPTION) for an explanation
of normal fan noise.

7 - 12

COOLING

CONDITION

POSSIBLE CAUSES

CORRECTION

INADEQUATE HEATER
PERFORMANCE. THERMOSTAT
FAILED IN OPEN POSITION

1. Has a Diagnostic trouble Code
(DTC) been set?

1. (Refer to 25 - EMISSIONS
CONTROL - DESCRIPTION) for
correct procedures and replace
thermostat if necessary

2. Coolant level low

2. (Refer to 7 - COOLING -
STANDARD PROCEDURE)

3. Obstructions in heater hose/
fittings

3. Remove heater hoses at both
ends and check for obstructions

4. Heater hose kinked

4. Locate kinked area and repair as
necessary

5. Water pump is not pumping
water to/through the 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 or the
heater core may be plugged.
Accessory drive belt may be
slipping causing poor water pump
operation.

5. (Refer to 7 - COOLING/ENGINE/
WATER PUMP - REMOVAL) If a
slipping belt is detected, (Refer to 7
- COOLING/ACCESSORY
DRIVE/DRIVE BELTS - DIAGNOSIS
AND TESTING). If heater core
obstruction is detected, (Refer to 24
- HEATING & AIR CONDITIONING -
DIAGNOSIS AND TESTING).

STEAM IS COMING FROM THE
FRONT OF VEHICLE NEAR THE
GRILL AREA WHEN WEATHER IS
WET, ENGINE IS WARMED UP
AND RUNNING, AND VEHICLE IS
STATIONARY. TEMPERATURE
GAUGE IS IN NORMAL RANGE

1. During wet weather, moisture
(snow, ice or rain condensation) on
the radiator will evaporate when the
thermostat opens. This opening
allows heated water into the
radiator. When the moisture
contacts the hot radiator, steam
may be emitted. This usually occurs
in cold weather with no fan or
airflow 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. (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
DESCRIPTION) Adjust coolant
mixture as necessary.

COOLANT LEVEL CHANGES IN
COOLANT RESERVE/OVERFLOW
TANK. TEMPERATURE GAUGE IS
IN NORMAL RANGE

1. Level changes are to be
expected as coolant volume
fluctuates with engine temperature.
If the level in the tank was between
the FULL and ADD marks at normal
operating temperature, the level
should return to within that range
after operation at elevated
temperatures.

1. A normal condition. No repair is
necessary.

COOLING

7 - 13

STANDARD PROCEDURE

DRAINING COOLING SYSTEM - ALL ENGINES

WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRES-
SURE. SERIOUS BURNS FROM COOLANT CAN
OCCUR.

DO NOT WASTE reusable coolant. If solution is clean,
drain coolant into a clean container for reuse.

1. Remove radiator pressure cap.

2. Loosen radiator petcock.

3. Remove cylinder block drain plugs (1).

REFILLING COOLING SYSTEM

WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRES-
SURE. SERIOUS BURNS FROM COOLANT CAN
OCCUR.

DO NOT WASTE reusable coolant. If solution is clean,
drain coolant into a clean container for reuse.

Clean cooling system prior to refilling. (Refer to 7 -
COOLING - STANDARD PROCEDURE).

1. Install cylinder block drain plugs. Coat the threads

with Mopar

Thread Sealant with Teflon.

2. Close radiator petcock.

3. Fill cooling system with a 50/50 mixture of water and antifreeze.

4. Fill coolant reserve/overflow tank to MAX mark on indicator stick.

5. Start and operate engine until thermostat opens (upper radiator hose warm to touch).

6. If necessary, add a 50/50 water and antifreeze mixture to the coolant reserve/overflow tank. This is done to

maintain coolant level between the MAX and MIN marks. The level in the reserve/overflow tank may drop below
the MIN mark after three or four warm-up and cool-down cycles.

ADDING ADDITIONAL COOLANT

The use of aluminum cylinder blocks, cylinder heads and water pumps requires special corrosion protection. Only
Mopar

Antifreeze/Coolant, 5 Year/100,000 Mile Formula (glycol base coolant with corrosion inhibitors called HOAT,

for Hybrid Organic Additive Technology) is recommended. This coolant offers the best engine cooling without cor-
rosion when mixed with 50% distilled water to obtain to obtain a freeze point of -37°C (-35°F). If it loses color or
becomes contaminated, drain, flush, and replace with fresh properly mixed coolant solution.

7 - 14

COOLING

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