For 1990-2009 cars

### Diagnostic Aids

The engine may overheat due to an intermittent operation of one of the following components:

• | Coolant Bypass Solenoid

• | Coolant Bypass Valve

• | Electric Cooling Fans

• | Thermostat

Concerning the cooling fan circuit check, refer to Testing for Intermittent Conditions and Poor Connections .

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
DEFINITION: Engine temperature lamp comes ON and stays ON, or the temperature gage shows hot, or coolant overflows from the surge tank onto the ground while the engine is running.
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Inspect the surge tank for low coolant. Is there a loss of coolant? | -- | Go to Loss of Coolant | Go to Step 3
3 | Important: Do not allow the engine temperature to exceed the specified value. Start the engine and allow to reach normal operating temperature. Does the engine begin to exceed the specified value? | 107°C (225°F) | Go to Step 4 | Go to Diagnostic Aids
4 |

1. Inspect for loose, damaged, and/or missing of the following:

• | A/C Condenser Seals

• | Front Air Deflector

• | Side Seals

2. Repair the system as necessary.

Does the engine still overheat?

--

Go to Step 5

Go to Step 18

5 | Using the J 23688 coolant and battery fluid tester, test for insufficient coolant concentration. Is the coolant protection greater than the specified value? | -37°C (-34°F) | Go to Step 6 | Go to Step 7
6 | Correct the coolant concentration as necessary. Does the engine still overheat? | -- | Go to Step 7 | Go to Step 18
7 | Inspect for obstructed radiator air flow or bent radiator fins. Is the radiator air flow obstructed? | -- | Go to Step 8 | Go to Step 9
8 | Clean the radiator. Refer to Radiator Cleaning . Does the engine still overheat? | -- | Go to Step 9 | Go to Step 18
9 | Inspect the drive belt tensioner. Refer to Drive Belt Tensioner Diagnosis for the 3.6L engine or Drive Belt Tensioner Diagnosis for the 4.6L engine. Is the drive belt tensioner working properly and is the tension correct? | -- | Go to Step 11 | Go to Step 10
10 | Replace the drive belt tensioner. Refer to Water Pump and Generator Belt Tensioner Replacement or Air Conditioning Compressor and Power Steering Pump Belt Tensioner Replacement for the 3.6L engine or Drive Belt Tensioner Replacement - Generator or Drive Belt Tensioner Replacement - Air Conditioning, Power Steering, and Water Pump for the 4.6L engine.

Does the engine still overheat?

--

Go to Step 11

Go to Step 18

11 | Inspect the thermostat for proper operation. Refer to Thermostat Diagnosis . Does the thermostat operate properly? | -- | Go to Step 13 | Go to Step 12
12 | Replace the thermostat. Refer to Engine Coolant Thermostat Replacement . Does the engine still overheat? | -- | Go to Step 13 | Go to Step 18
13 | Inspect the afterboil coolant pump for an inoperative if equipped. Does the engine still overheat? | -- | Go to Step 14 | Go to Step 18
14 | Inspect for an inoperative cooling fan. Refer to Cooling Fan Inoperative . Does the engine still overheat? | -- | Go to Step 15 | Go to Step 18
15 | Inspect for blocked cooling system passages. Are the cooling system passages blocked? | -- | Go to Step 16 | Go to Step 17
16 | Replace the radiator. Refer to Radiator Replacement . Does the engine still overheat? | -- | Go to Step 17 | Go to Step 18
17 | Replace the engine water pump. Refer to Water Pump Replacement . Did you complete the repairs? | -- | Go to Step 18 | --
18 | Operate the system in order to verify the repairs. Did you correct the problem? | -- | System OK | Go to Step 2