Dodge Nitro. Manual — part 505

shorted. Also, corroded or loose
wiring in this circuit.

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 cooling
system (air build up in the cooling
system causing the thermostat to
open late).

5. Check and correct coolant leaks.
See 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
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.

8. Loose accessory drive belt.

8. See DIAGNOSIS AND
TESTING. Check and correct as
necessary.

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 OR COOLANT TO
COOLANT RECOVERY
CONTAINER. TEMPERATURE
GAUGE READING MAY BE
ABOVE NORMAL BUT NOT
HIGH. COOLANT LEVEL MAY
BE HIGH IN COOLANT
RECOVERY CONTAINER.

1. Pressure relief valve in radiator
pressure cap is defective.

1. Check condition of radiator cap
and cap seals. See DIAGNOSIS
AND TESTING. Replace cap as
necessary.

2. Overfilled cooling system or
extremely low coolant level.

2. Wait for engine to cool and
adjust coolant level.

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. See DIAGNOSIS
AND TESTING.

DETONATION OR PRE-
IGNITION (NOT CAUSED BY

1. Engine overheating.

1. Check reason for overheating
and repair as necessary.

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro

IGNITION SYSTEM). GAUGE
MAY OR MAY NOT BE
READING HIGH

2. Freeze point of coolant not
correct. Mixture is too rich or too
lean.

2. Check coolant concentration.
See DESCRIPTION, and adjust
ratio as required.

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. See DIAGNOSIS AND
TESTING. Replace if necessary.
(b) Hose between coolant
reserve/overflow tank and radiator
is kinked. Repair as necessary.
(c) Vent at coolant
reserve/overflow tank is plugged.
Clean vent and repair as
necessary.
(d) Reserve/overflow tank is
internally blocked or plugged.
Check for blockage and repair as
necessary.

INADEQUATE HEATER
PERFORMANCE.

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

1. Refer to EMISSIONS
CONTROL

2. Coolant level low.

2. See DIAGNOSIS AND
TESTING.

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. If a slipping belt is detected, see
REMOVAL. If heater core
obstruction is detected, . See
STANDARD PROCEDURE for
cooling system reverse flushing.

STEAM IS COMING FROM
THE FRONT OF VEHICLE
NEAR THE GRILLE 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 or condenser will
evaporate when the thermostat
opens. This opening allows heated
water into the radiator. When the
moisture contacts the hot radiator
or condenser, steam may be
emitted. This usually occurs in
cold weather with no fan or

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

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro

AERATION

Low coolant level in a cross flow radiator will equalize in both tanks with engine off. With engine running and
at operating temperature, the high pressure inlet tank runs full and the low pressure outlet tank drops, resulting
in cooling system aeration. Aeration will draw air into the water pump resulting in the following:

High reading shown on the temperature gauge.

Loss of coolant flow through the heater core.

Corrosion in the cooling system.

Water pump seal may run dry, increasing the risk of premature seal failure.

Combustion gas leaks into the coolant can also cause aeration.

airflow to blow it away.

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. See DESCRIPTION for
coolant concentration information.
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.

FAN RUNS ALL THE TIME

1. Fan control sensors inoperative. 1. Check for DTCs. Verify sensor

readings.

2. Transmission temperature too
high.

2. Check for transmission over
temp DTC.

3. Engine coolant temperature too
high.

3. (a) Check coolant level. Correct
level as required.
(b) Thermostat stuck. Replace
thermostat.
(c) Water pump failed. Replace
water pump.
(d) Coolant flow restricted. Clean
radiator.
(e) Air flow over radiator
obstructed. Remove obstruction.

4. ECM or TIPM defective.

4. Replace ECM or TIPM

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro

LEAK TESTING

ULTRAVIOLET LIGHT METHOD

Fig. 2: Identifying Black Light Tool
Courtesy of CHRYSLER LLC

A leak detection additive is available through the parts department that can be added to cooling system. The
additive is highly visible under ultraviolet light (black light). Pour one ounce of additive into cooling system.
Place heater control unit in HEAT position. Start and operate engine until radiator upper hose is warm to touch.
Aim the commercially available black light tool at components to be checked. If leaks are present, black light
will cause additive to glow a bright green color.

The black light (1) can be used in conjunction with a pressure tester to determine if any external leaks exist.

PRESSURE TESTER METHOD

1 - TYPICAL BLACK LIGHT TOOL

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro