Step
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Action
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Yes
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No
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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 radiator cap onto the ground while the
engine is running. |
|
1
|
|
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
Diagnostic System Check - Vehicle
|
3
|
|
1. |
Verify that the cooling fans are operating
properly. |
|
2. |
Repair the cooling fan system, as necessary. |
Does the engine still overheat?
|
Go to Step 4
|
System OK
|
4
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Perform the following inspections:
• |
Inspect the radiator and the A/C condenser cooling
fins for debris or any other obstruction. |
• |
Inspect the drive belt system and the drive belt
tensioner for proper operation in order to ensure that the coolant
pump is rotating properly. |
• |
Inspect for loose, damaged and/or missing air
deflector(s). |
• |
Check for a pinched or kinked cooling system
hose. |
• |
Repair the systems as necessary. |
Does the engine still overheat?
|
Go to Step 5
|
System OK
|
5
|
Inspect the thermostat for proper operation. Refer to
Thermostat Diagnosis .
Is the thermostat operating properly?
|
Go to Step 7
|
Go to Step 6
|
6
|
Replace the thermostat. Refer to
Engine Coolant Thermostat Replacement .
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 proper coolant concentration
(mixture). Correct the coolant concentration as necessary. |
|
2. |
Remove the radiator 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 |
• |
A 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. Refer to
Coolant System Flushing
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
coolant pump. Refer to
Water Pump Replacement
Does the engine still overheat?
|
Go to Step 1
|
System OK
|