Dodge Nitro. Manual - part 506

Fig. 3: Pressure Testing Cooling System 
Courtesy of CHRYSLER LLC 

The engine should be at normal operating temperature. Recheck the system cold if cause of coolant loss is not 
located during the warm engine examination. 

Carefully remove radiator pressure cap from pressure bottle and check coolant level. Push down on cap to 
disengage it from stop tabs. Wipe inside of filler neck and examine lower inside sealing seat for nicks, cracks, 
paint, and dirt. Inspect radiator-to- reserve/overflow tank hose for internal obstructions. Insert a wire through 
the hose to be sure it is not obstructed. 

Inspect cams on outside of filler neck. If cams are damaged, seating of pressure cap valve and tester seal will be 
affected. 

Attach pressure tester (7700 or an equivalent) to radiator filler neck. 

Operate tester pump (1) to apply 110 kPa (16 psi) pressure to system. If hoses enlarge excessively or bulges 

1 - TYPICAL COOLING SYSTEM PRESSURE TESTER

WARNING:

Hot, pressurized coolant can cause injury by scalding.

 

2007 Dodge Nitro R/T 

2007 ENGINE Cooling - Nitro

  

while testing, replace as necessary. Observe gauge pointer and determine condition of cooling system according 
to following criteria: 

Holds Steady: If pointer remains steady for two minutes, serious coolant leaks are not present in system. 
However, there could be an internal leak that does not appear with normal system test pressure. If it is certain 
that coolant is being lost and leaks cannot be detected, inspect for interior leakage or perform Internal Leakage 
Test. 

Drops Slowly: Indicates a small leak or seepage is occurring. Examine all connections for seepage or slight 
leakage with a flashlight. Inspect radiator, hoses, gasket edges and heater. Seal small leak holes with a Sealer 
Lubricant (or equivalent). Repair leak holes and inspect system again with pressure applied. 

Drops Quickly: Indicates that serious leakage is occurring. Examine system for external leakage. If leaks are 
not visible, inspect for internal leakage. Large radiator leak holes should be repaired by a reputable radiator 
repair shop. 

INTERNAL LEAKAGE INSPECTION 

Remove engine oil pan drain plug and drain a small amount of engine oil. If coolant is present in the pan, it will 
drain first because it is heavier than oil. An alternative method is to operate engine for a short period to churn 
the oil. After this is done, remove engine dipstick and inspect for water globules. Also inspect transmission 
dipstick for water globules and transmission fluid cooler for leakage. 

Operate engine without pressure cap on radiator until thermostat opens. Attach a Pressure Tester to filler neck. 
If pressure builds up quickly it indicates a combustion leak exists. This is usually the result of a cylinder head 
gasket leak or crack in engine. Repair as necessary. 

If there is not an immediate pressure increase, pump the Pressure Tester. Do this until indicated pressure is 
within system range of 110 kPa (16 psi). Fluctuation of gauge pointer indicates compression or combustion 
leakage into cooling system. 

Because the vehicle is equipped with a catalytic converter, do not remove spark plug cables or short out 
cylinders to isolate compression leak. 

If the needle on dial of pressure tester does not fluctuate, race engine a few times to check for an abnormal 
amount of coolant or steam. This would be emitting from exhaust pipe. Coolant or steam from exhaust pipe may 
indicate a faulty cylinder head gasket, cracked engine cylinder block or cylinder head. 

A convenient check for exhaust gas leakage into cooling system is provided by a commercially available Block 
Leak Check tool. Follow manufacturers instructions when using this product.

WARNING:

With radiator pressure tester tool installed on radiator, do not allow 
pressure to exceed 124 kpa (18 psi). Pressure will build up quickly if a 
combustion leak is present. To release pressure, rock tester from side to 
side. When removing tester, do not turn tester more than 1/2 turn if 
system is under pressure.

 

2007 Dodge Nitro R/T 

2007 ENGINE Cooling - Nitro

  

COMBUSTION LEAKAGE TEST - WITHOUT PRESSURE TESTER

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

Drain sufficient coolant to allow thermostat removal. See REMOVAL. Remove accessory drive belt . See 
REMOVAL.  

Add coolant to radiator to bring level to within 6.3 mm (1/4 in) of top of thermostat housing. 

Start engine and accelerate rapidly three times, to approximately 3000 RPM while observing coolant. If internal 
engine combustion gases are leaking into cooling system, bubbles will appear in coolant. If bubbles do not 
appear, internal combustion gas leakage is not present. 

STANDARD PROCEDURE 

DRAINING 

WARNING:

Do not remove cylinder block drain plugs or loosen radiator draincock 
with system hot and under pressure. Serious burns from coolant can 
occur.

CAUTION: Avoid overheating. Do not operate engine for an excessive period of time. 

Open draincock immediately after test to eliminate boil over.

 

2007 Dodge Nitro R/T 

2007 ENGINE Cooling - Nitro

  

Fig. 4: Identifying Cylinder Block Drain Plug & Exhaust Mainfold And Heat Shield 
Courtesy of CHRYSLER LLC 

1. DO NOT remove radiator cap first. With engine cold, raise vehicle on a hoist and locate radiator 

draincock. 

1 - CYLINDER BLOCK DRAIN PLUG
2 - EXHAUST MANIFOLD AND HEAT SHIELD

WARNING:

Do not remove the cylinder block drain plugs (1) or loosen the radiator 
draincock with system hot and under pressure. Serious burns from 
coolant can occur.

NOTE:

Radiator draincock is located on the left/lower side of radiator facing to 
rear of vehicle.

 

2007 Dodge Nitro R/T 

2007 ENGINE Cooling - Nitro