To determine whether coolant is flowing through the cooling system, use one of the following procedures:

PREFERRED METHOD

WARNING: Do not remove the cooling system pressure cap or any hose with the system hot and under pressure because serious burns from coolant can occur.

• 2.4L: Remove pressure cap when engine is cold. Remove small amount of coolant. Idle engine until thermostat opens. You should observe coolant flow while looking down the filler neck. Once flow is detected install the pressure cap. Replace removed coolant into coolant recovery container.
• 2.7L/3.5L/2.0L Diesel: Start engine, coolant flow should be observable in coolant pressure container when revving the engine.

ALTERNATIVE METHOD

• If engine is cold, idle engine until normal operating temperature is reached. Feel the upper radiator hose.

If it is hot, coolant is circulating.

LEAK TESTING

WARNING: If vehicle has been run recently, wait 15 minutes before removing pressure cap. Place a shop towel over the cap, and without pushing down, rotate it counterclockwise to the first stop. Allow fluids to escape through the overflow tube. When the system stops pushing coolant and steam into the coolant recovery bottle and pressure drops, push down on the cap and remove it completely. Squeezing the radiator inlet hose with a shop towel (to check pressure) before and after turning to the first stop is recommended.

Coolant level should be full. Add coolant if necessary. With engine not running, remove pressure cap and wipe the coolant filler neck sealing seat clean.

Attach a cooling system pressure tester Tool 7700 (or equivalent) to the coolant filler neck, apply 104 kPa (15 psi) pressure. If the pressure drops more than 13.7 kPa (2 psi) in 2 minutes inspect all points for external leaks.

All hoses, radiator and heater, should be moved while at 104 kPa (15 psi) since some leaks occur while driving due to engine rock, etc.

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 temperature in order to open the thermostat and allow the coolant to expand.

Reattach the tester. If the needle on the dial fluctuates, it indicates a combustion leak and is usually a head gasket leak.

WARNING: With tool in place pressure builds up fast. Any excessive amount of pressure built up by continuous engine operation must be released to a safe pressure point. never permit pressure to exceed 138 kPa (20 psi).

If the needle on the dial does not fluctuate, race the engine a few times. If an abnormal amount of coolant or steam is emitted from the tailpipe, it may indicate a faulty head gasket, cracked engine block or cylinder head.

There may be internal leaks which can be determined by removing the oil dipstick. If water globules appear intermixed with the oil, it will indicate a internal leak in the engine. If there is an internal leak, the engine must be disassembled for repair.

AERATION

Low coolant level in a cross flow radiator will equalize in both tanks with engine off. With engine at 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 the above problems.

DEAERATION

2.4L

Removal of air from the engine cooling system only occurs when the engine is first warming up. Air in the cooling system will collect under the cooling system pressure cap while the engine is run and will be pushed into the coolant recovery container. When the engine cools down, coolant will be drawn from the coolant recovery container back into the active cooling system. Once the thermostat opens, deaeration no longer occurs.

Multiple warm up and cool down cycles may be required to remove all the air in the cooling system. If the system is very low on coolant, deaeration will not occur. Following the proper cooling system fill procedure is essential for proper operation. This system will not function if the wrong cooling system pressure cap is installed. Ensure proper cooling system pressure cap is used. Verify proper pressure cap part number.

2.7L/3.5L/2.0L DIESEL

This engine has a pressure system to remove air from the engine cooling system. Removal of air from the engine cooling system occurs continuously when the engine is run at speeds above idle. Thirty minutes of normal driving after a properly completed service fill will deaerate the engine cooling system. This system will not function if the wrong cooling system pressure cap is installed. Ensure proper cooling system pressure cap is used. Verify proper pressure cap part number.