For 1990-2009 cars

### Preliminary Diagnosis

Verify that overheating is not caused by the following conditions:

1. While pulling a trailer that is within the recommended towing weight
2. After prolonged idle in gear, with the A/C system operating
3. After prolonged driving in slow city traffic, traffic jams, parades, etc.

If these conditions can be eliminated as the cause of overheating, refer to the table below.

#### Engine Overheats

Possible Cause | Correction
--- | ---
Coolant level or mixture incorrect | Check the coolant mixture and add coolant as necessary.
Air trapped in cooling system | Refill the cooling system. Refer to Cooling System Draining and Filling .
Surge tank outlet hose pinched or kinked, especially at radiator | Relieve kinks by re-routing. Replace the hose if necessary.
Radiator fins obstructed | Remove or relocate add-on parts that block air to the radiator. Clean away bugs, leaves, etc. In cold climates, clear away snow, etc. from the radiator core.
Loose, damaged and or missing air seals, deflector or fan shroud | Repair or replace as required.
Thermostat malfunction - stuck in closed position | Inspect and replace the thermostat. Refer to Engine Coolant Thermostat Replacement .
Cooling fan malfunction | Check the cooling fan for missing fan blades or loose fan belt. Replace the fan if necessary. Refer to Fan Replacement or Condenser Fan Inoperative if equipped with air conditioning.
Cooling system passages restricted |

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

Incorrect temperature gage reading | Check the temperature gauge for proper operation. Connect a Scan Tool to the vehicle and read the system temperature. Compare this reading to the temperature gauge. Replace the gage if necessary. Refer to Fuel/Temperature Gage Replacement
Loss of system pressure Check the following areas for possible leakage:

• | Hoses

• | Coolant pump

• | Heater core

• | Thermostat housing

• | Radiator

• | Core plugs

• | Head gaskets

• | Intake manifold gaskets

Pressure check the system and cap. Ensure the correct cap is being used.

Malfunctioning coolant pump, eroded or broken impeller blades | Replace the coolant pump. Refer to Water Pump Replacement .
Incorrect radiator | Check the radiator usage chart in a parts catalog. If needed, replace with the correct radiator.