GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: The engine temperature lamp comes on and stays on, or temperature gage shows hot, or coolant overflows from the surge tank onto the ground while the engine is running.

1

Check for a loss of coolant. Refer to Loss of Coolant .

Is there a loss of coolant?

--

Go to Step 2

Go to Step 3

2

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

Does the engine still overheat?

--

Go to Step 3

System OK

3

Check for kinked or pinched surge tank hoses, especially at the radiator.

Are any surge tank hoses kinked or pinched?

--

Go to Step 4

Go to Step 5

4

  1. Relieve any kinks by rerouting the hoses.
  2. Replace the hoses if necessary.

Does the engine still overheat?

--

Go to Step 5

System OK

5

Check for loose, missing or damaged radiator air seals or deflectors.

Are there any loose, missing or damaged radiator air seals or deflectors?

--

Go to Step 6

Go to Step 7

6

Repair or replace any loose, missing or damaged radiator air seals or deflectors. Refer to Radiator Air Baffle Assemblies and Deflectors .

Does the engine still overheat?

--

Go to Step 7

System OK

7

Check the coolant concentration.

Does the coolant concentration test correctly?

--

Go to Step 9

Go to Step 8

8

Replace the coolant if necessary. Refer to Cooling System Draining and Filling .

Does the engine still overheat?

--

Go to Step 9

System OK

9

Important: Use the correct pressure cap.

Check the system for loss of pressure.

Is there a loss of pressure?

--

Go to Step 10

Go to Step 11

10

Repair any leaks as necessary.

Does the engine still overheat?

--

Go to Step 11

System OK

11

Check for a faulty engine coolant temperature sensor (ECT).

Is the engine coolant temperature sensor faulty?

--

Go to Step 12

Go to Step 13

12

Replace the ECT. Refer to Engine Coolant Temperature Sensor Replacement in Engine Controls - 2.2L or Engine Coolant Temperature Sensor Replacement in Engine Controls - 2.4L.

Does the engine still overheat?

--

Go to Step 13

System OK

13

Check the radiator for any air flow obstructions or bent fins.

Is there any airflow obstruction or bent fins?

--

Go to Step 14

Go to Step 15

14

  1. Remove or relocate add-on parts that block air flow to the radiator.
  2. Clean any debris from the radiator core.

Does the engine still overheat?

--

Go to Step 15

System OK

15

Check for any blocked cooling system passages.

Are there any blocked cooling system passages?

--

Go to Step 16

Go to Step 17

16

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

Does the engine still overheat?

--

Go to Step 17

System OK

17

Check for an inoperative cooling fan.

Is the cooling fan inoperative?

--

Go to Step 18

Go to Step 19

18

Replace the cooling fan. Refer to Engine Cooling Fan Replacement .

Does the engine still overheat?

--

Go to Step 19

System OK

19

Check for a thermostat that is stuck closed.

Is the thermostat stuck closed?

--

Go to Step 20

Go to Step 21

20

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Does the engine still overheat?

--

Go to Step 21

System OK

21

Check for a faulty water pump. The impeller blades may be eroded or broken.

Is the water pump faulty?

--

Go to Step 22

--

22

Replace the water pump. Refer to Water Pump Replacement .

Does the engine still overheat?

--

--

System OK