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Engine Overheating

Step

Action

Yes

No

DEFINITION: Either of the following conditions indicate a probable engine overheat condition.

    • The engine temperature gauge is in the red (overheat) zone and/or the engine temperature indicator is ON.
    • Hot engine coolant overflows from the coolant recovery reservoir and/or coolant pressure cap onto the ground while the engine is running.

1
  1. Inspect and fill the cooling system, as necessary.
  2. Inspect the cooling system for leaks, as necessary.
  3. Repair the cooling system leaks, as necessary.

Has the inspection/repair been performed?

Go to Step 2

-

2
  1. Start the engine and allow the engine to run at approximately 1 200 RPM.
  2. Use the Scan Tool in order to verify the overheat condition.

Does the Scan Tool verify the engine overheat condition?

Go to Step 3

Go to Engine Cooling Schematics

3
  1. Verify that the cooling fans are operating correctly.
  2. Repair the cooling fan system, as necessary.

Does the engine still overheat?

Go to Step 4

System OK

4

Perform the following inspections:

    •  Inspect the radiator and the A/C condenser cooling fans for debris or any other obstruction
    • Inspect the drive belt system and the drive belt tensioner for correct operation in order to ensure that the water pump is rotating correctly.
    •  Inspect for loose, damaged and/or missing air deflector(s).
    •  Check for a pinched or kinked cooling system hose.
    • Repair the system if necessary.

Does the engine still overheat?

Go to Step 5

System OK

5

Inspect the thermostat for correct operation.

Does the thermostat operate correctly?

Go to Step 7

Go to Step 6

6

Replace the thermostat.

Does the engine still overheat?

Go to Step 7

System OK

7

Note: Excessive coolant freeze point protection MAY cause the coolant to boil at low temperatures.

  1. Inspect for the correct coolant concentration (mixture). Correct the coolant concentration as necessary.
  2. Remove the coolant pressure cap.
  3. Start the engine and inspect for a constant flow of air bubbles in the engine coolant.

Is there a constant flow of air bubbles in the engine coolant?

Go to Step 8

Go to Step 9

8

The probable cause of the engine overheat is combustion chamber gasses leaking into the cooling system. This condition is usually caused by the following:

    • A worn or damaged cylinder head gasket.
    • Worn or damaged cylinder head.
    • A worn and/or damaged engine block.

Verify this condition by inspecting the spark plug electrodes and porcelain surrounding the spark plug electrode for signs of coolant. Replace and/or repair the engine internal component(s), as necessary, in order to repair the engine internal coolant leak.

Does the engine still overheat?

Go to Step 1

System OK

9

The engine overheat may be caused by a cooling system blockage. Flush the cooling system.

Does the engine still overheat?

Go to Step 10

System OK

10

Note: It is unlikely that the water pump is the cause of the overheat condition.

If NONE of the cooling system passages are restricted, replace the water pump.

Does the engine still overheat?

Go to Step 1

System OK

   


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