DEFINITION: Engine temperature lamp comes on and stays on, or temperature gauge 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?

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Go to Step 2

Go to Step 3

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

Does the engine still overheat?

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Go to Step 3

System OK

1. Check to see if any of the surge tank hoses are kinked or pinched, especially at the radiator.
2. Relieve any kinks by re-routing the hoses. Replace the hoses if necessary.

Does the engine still overheat?

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Go to Step 4

System OK

1. Check for loose, missing or damaged radiator air seals or deflectors.
2. Repair or replace the part(s) as necessary. Refer to Radiator Air Baffle Assemblies and Deflectors .

Does the engine still overheat?

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Go to Step 5

System OK

Check the coolant concentration. Refer to Coolant Concentration Testing .

Does the engine still overheat?

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Go to Step 6

System OK

1. Check the system for loss of pressure.
2. Do a system pressure test. Refer to Cooling System Leak Testing .
3. Make sure the correct pressure cap is being used.

Does the engine still overheat?

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Go to Step 7

System OK

Check for a faulty Engine Coolant Temperature (ECT) sensor. Refer to Electrical Diagnosis.

Does the engine still overheat?

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Go to Step 8

System OK

1. Check the radiator for any air flow obstruction.
2. Check the radiator for bent fins.
3. Remove or relocate add-on parts that block air flow to the radiator.
4. Clean any bugs, leaves, or snow from the radiator core. Refer to Cooling System Maintenance Recommendations .

Does the engine still overheat?

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Go to Step 9

System OK

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

Does the engine still overheat?

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Go to Step 10

System OK

1. Check for an inoperative cooling fan. Refer to Electrical Diagnosis.
2. Repair as necessary.

Does the engine still overheat?

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Go to Step 11

System OK

1. Check for a stuck closed thermostat. Refer to Thermostat Diagnosis .
2. Replace the thermostat as necessary. Refer to Engine Coolant Thermostat Replacement .

Does the engine still overheat?

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Go to Step 12

System OK

1. Check for a faulty coolant pump. The impeller blades may be eroded or broken.
2. Replace the coolant pump as necessary. Refer to Water Pump Replacement .

Is the repair complete?

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System OK

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