DEFINITION: The engine temperature lamp comes on and stays on, or temperature gage shows hot, or coolant overflows from the surge tank onto the ground while the engine is running.

Check for a loss of coolant. Refer to Loss of Coolant.

Is there a loss of coolant?

Go to Step 2

Go to Step 3

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

Does the engine still overheat?

Go to Step 3

System OK

Check for kinked or pinched surge tank hoses, especially at the radiator.

Are any surge tank hoses kinked or pinched?

Go to Step 4

Go to Step 5

1. Relieve any kinks by rerouting the hoses.
2. Replace the hoses, if necessary.

Does the engine still overheat?

Go to Step 5

System OK

Check for loose, missing, or damaged radiator air seals or deflectors.

Are there any loose, missing, or damaged radiator air seals or deflectors?

Go to Step 6

Go to Step 7

Repair or replace any loose, missing, or damaged radiator air seals or deflectors.

Does the engine still overheat?

Go to Step 7

System OK

Check the coolant concentration.

Does the coolant concentration test correctly?

Go to Step 9

Go to Step 8

Replace the coolant, if necessary. Refer to Cooling System Draining and Filling.

Does the engine still overheat?

Go to Step 9

System OK

Important: Use the correct pressure cap.

Check the system for loss of pressure.

Is there a loss of pressure?

Go to Step 10

Go to Step 11

Repair any leaks, as necessary.

Does the engine still overheat?

Go to Step 11

System OK

Check for a faulty engine coolant temperature (ECT) sensor.

Is the engine coolant temperature sensor faulty?

Go to Step 12

Go to Step 13

Replace the ECT. Refer to Engine Coolant Temperature Sensor Replacement, Engine Coolant Temperature Sensor Replacement or Engine Coolant Temperature Sensor Replacement.

Does the engine still overheat?

Go to Step 13

System OK

Check the radiator for any air flow obstructions or bent fins.

Is there any airflow obstruction or bent fins?

Go to Step 14

Go to Step 15

1. Remove or relocate add-on parts that block air flow to the radiator.
2. Clean any debris from the radiator core.

Does the engine still overheat?

Go to Step 15

System OK

Check for any blocked cooling system passages.

Are there any blocked cooling system passages?

Go to Step 16

Go to Step 17

1. Remove any obstruction.
2. Flush the cooling system, as required. Refer to Flushing.
3. Refill the coolant. Refer to Cooling System Draining and Filling.

Does the engine still overheat?

Go to Step 17

System OK

Check for an inoperative cooling fan.

Is the cooling fan inoperative?

Go to Step 18

Go to Step 19

Replace the cooling fan. Refer to Cooling Fan and Shroud Replacement.

Does the engine still overheat?

Go to Step 19

System OK

Check for a thermostat that is stuck closed.

Is the thermostat stuck closed?

Go to Step 20

Go to Step 21

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement.

Does the engine still overheat?

Go to Step 21

System OK

Check for a faulty water pump. The impeller blades may be eroded or broken.

Is the water pump faulty?

Go to Step 22

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Replace the water pump. Refer to Water Pump Replacement.

Does the engine still overheat?

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System OK