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