DEFINITION: The cooling system is losing coolant either internally or externally.

Were you sent here from Symptoms or another diagnostic table?

Go to Step 2

Go to Symptoms - Engine Cooling

Repair any present DTCs. Refer to Diagnostic System Check - Vehicle .

Is the action complete?

Go to Step 3

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Inspect the coolant level.

Is the coolant at the proper level?

Go to Step 5

Go to Step 4

Fill the cooling system to the proper level. Refer to Cooling System Draining and Filling .

Is the action complete?

Go to Step 5

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If the engine is suspected to have a coolant leak into a cylinder, the coolant can hydraulically lock the engine.

Does the engine crankshaft rotate?

Go to Step 6

Go to Step 28

Engine overheating can cause a loss of coolant.

Is the engine overheating?

Go to Step 29

Go to Step 7

Extended operation with a low coolant level can cause engine internal component failure.

Is the engine knocking?

Go to Step 31

Go to Step 8

1. Idle the engine at normal operating temperature.
2. Inspect for heavy white smoke coming out of the exhaust pipe.

Is a heavy white smoke present from the exhaust pipe?

Go to Step 9

Go to Step 10

Coolant in the exhaust system creates a distinctive, burning coolant odor in the exhaust.

Condensation in the exhaust system can cause an odorless white smoke during engine warm up.

Does the white smoke have a burning coolant type odor?

Go to Step 30

Go to Step 10

Caution: Refer to Moving Parts and Hot Surfaces Caution in the Preface section.

With the engine idling, inspect the coolant recovery system.

Does the coolant recovery system discharge coolant while the engine is idling?

Go to Step 15

Go to Step 11

Visually inspect the hoses, pipes and hose clamps at the following locations:

Are any of the hoses, clamps or pipes leaking?

Go to Step 22

Go to Step 12

Visually inspect the following components:

Are any of the listed components leaking?

Go to Step 22

Go to Step 13

1. Pressure test the cooling system. Refer to Cooling System Leak Testing .
2. With the cooling system pressurized, visually inspect the components listed in steps 11 and 12.

Are any leaks present?

Go to Step 22

Go to Step 14

Pressure test the coolant pressure cap. Refer to Pressure Cap Testing .

Does the coolant pressure cap hold pressure?

Go to Step 16

Go to Step 23

Pressure test the coolant pressure cap. Refer to Pressure Cap Testing .

Does the coolant pressure cap hold pressure?

Go to Step 32

Go to Step 23

Inspect for the following conditions:

Is coolant present?

Go to Step 24

Go to Step 17

1. Add 30 ml (1 oz) of GM P/N 89022219 (Canadian P/N 89022220) coolant leak detection dye to the cooling system for each 15 L (4 gal) of coolant. Refer to Approximate Fluid Capacities .
2. Start the vehicle and allow the engine to reach normal operating temperature.
3. Shut the engine off.
4. Use the J 42220 Universal 12V Leak Detection Lamp to visually inspect the components listed in steps 11 and 12.

Are any leaks present?

Go to Step 22

Go to Step 18

Use the J 42220 to inspect for the following conditions:

Is coolant dye present?

Go to Step 24

Go to Step 19

Inspect the underside of the engine oil fill cap for a gray/white milky substance.

Is a milky substance under the oil fill cap?

Go to Step 20

Go to Step 21

Inspect the engine oil fluid level indicator for a gray/white milky substance.

Is a milky substance on the engine oil fluid level indicator?

Go to Step 30

Go to Step 21

Inspect the automatic transmission oil fluid level indicator, if equipped, for a gray/white milky substance.

Is there a milky substance on the automatic transmission fluid level indicator?

Go to Step 25

Go to Step 33

Repair or replace the leaking component. Refer to the appropriate repair.

Is the repair complete?

Go to Step 33

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Replace the coolant pressure cap.

Is the repair complete?

Go to Step 33

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Replace the heater core. Refer to Heater Core Replacement .

Is the repair complete?

Go to Step 33

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1. Remove the transmission oil cooler lines from the radiator.
2. Pressure test the cooling system. Refer to Cooling System Leak Testing .
3. Inspect the transmission oil cooler for coolant.

Is coolant present?

Go to Step 26

Go to Step 27

1. Replace the radiator. Refer to Radiator Replacement .
2. Service the automatic transmission. Refer to Engine Coolant/Water in Transmission .

Is the repair complete?

Go to Step 33

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Install the cooler lines to the radiator.

Is the action complete?

Go to Step 33

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Repair the engine no crank condition. Refer to the appropriate procedure:

Is the repair complete?

Go to Step 33

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Repair the engine overheating condition. Refer to Engine Overheating .

Is the repair complete?

Go to Step 33

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Repair the engine internal coolant leak. Refer to the appropriate procedure:

Is the repair complete?

Go to Step 33

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Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed .

Is the repair complete?

Go to Step 33

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Repair the combustion pressure in the cooling system problem. Refer to the appropriate procedure:

Is the repair complete?

Go to Step 33

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Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2