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 the temperature gage shows hot, or coolant overflows from the surge tank onto the ground while the engine is running.

1

Check for low coolant.

Is the coolant low?

--

Go to Step 2

Go to Step 3

2

Fill the system to the specified level.

Does the engine still overheat?

--

Go to Step 3

System OK

3

Check for a missing or damaged radiator upper air deflector, baffle, or center air deflector.

Are there any missing or damaged deflectors or baffles?

--

Go to Step 4

Go to Step 5

4

Repair or replace any deflectors or baffles as necessary.

Does the engine still overheat?

--

Go to Step 5

System OK

5

Check the coolant concentration.

Is the coolant concentration adequate?

--

Go to Step 7

Go to Step 6

6

Correct the coolant concentration as necessary.

Does the engine still overheat?

--

Go to Step 7

System OK

7

Pressure test the cooling system.

Does the cooling system maintain the correct pressure?

103 kPa (15 psi)

Go to Step 9

Go to Step 8

8

Refer to Loss of Coolant .

Does the engine still overheat?

--

Go to Step 9

System OK

9

Check for a pinched or kinked radiator surge tank hose.

Is the surge tank hose kinked or damaged?

--

Go to Step 10

Go to Step 11

10

Reroute or replace the hose as necessary.

Does the engine still overheat?

--

Go to Step 11

System OK

11

Check the water pump belt tension.

Is the tensioner working properly?

--

Go to Step 13

Go to Step 12

12

Replace the tensioner as necessary.

Does the engine still overheat?

--

Go to Step 13

System OK

13

Check for an obstructed radiator air flow or bent fins.

Are any radiator fins bent or is air flow to the radiator being obstructed?

--

Go to Step 14

Go to Step 15

14

Remove or relocate add on parts that block air flow to the radiator.

Does the engine still overheat?

--

Go to Step 15

System OK

15

Check for a blockage in the cooling system passages.

Are the cooling system passages blocked?

--

Go to Step 16

Go to Step 17

16

  1. Drain the coolant. Refer to Cooling System Draining and Filling .
  2. Flush the cooling system. Refer to Flushing .

Does the engine still overheat?

--

Go to Step 17

System OK

17

Check for an inoperative cooling fan.

Are the cooling fans inoperative?

--

Go to Step 18

Go to Step 19

18

Repair or replace the cooling fan as necessary. Refer to Engine Coolant Fan Motor Replacement .

Does the engine still overheat?

--

Go to Step 19

System OK

19

Check if the thermostat is stuck in the closed position.

Is the thermostat sticking or stuck in the closed position?

--

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.

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