GM Service Manual Online
For 1990-2009 cars only

Hot Light On, Hissing, Rumble, Steam, Power Loss

Step

Action

Value(s)

Yes

No

1

Check the coolant level.

Is the coolant level low?

--

Go to Step 2

Go to Step 4

2

  1. Add coolant to the system.
  2. Check for visual leaks.

Are there leaks in the system?

--

Go to Loss of Coolant .

Go to Step 3

3

Pressure test the system.

Are there leaks in the system?

--

Go to Loss of Coolant .

Go to Step 4

4

Check the condition of the drive belt.

Is the drive belt loose?

--

Go to Drive Belt Diagnosis in Engine Mechanical.

Go to Step 5

5

Check the hoses.

Have the hoses collapsed?

--

Go to Step 6

Go to Step 7

6

Replace the hoses.

Refer to Radiator Hose Replacement .

Does the engine still overheat?

--

Go to Step 7

System OK

7

Check the temperature level of the thermostat.

Is the temperature level high?

--

Go to Step 8

Go to Step 9

8

Replace the thermostat. Use any of the following procedures:

Does the engine still overheat?

--

Go to Step 9

System OK

9

Check the radiator.

Is the radiator clogged?

--

Go to Inspection Maintenance Recommendations.

Go to Step 10

10

Check the engine block.

Is the engine block clogged?

--

Go to Inspection Maintenance Recommendations.

Go to Step 9

11

Check for gas leaks into the system.

Is there a gas leak into the engine block?

--

Go to Step 10

Go to Step 11 or Go to step 12

12

Check for bubbles in the coolant.

Are there bubbles in the coolant?

--

Go to System Checks.

--

13

Check the water pump.

Are there bubbles in the coolant?

--

Go to Step 14

System OK

14

Replace the water pump. Use any of the following procedures:

    • Refer to Water Pump Replacement .
    • Refer to Water Pump Replacement .
    • Refer to Water Pump Replacement .
    • Refer to Water Pump Replacement .

Does the engine still overheat?

--

Go to Step 15

System OK

15

Check the radiator fan clutch.

Is the radiator fan clutch operating normally?

--

Go to Step 16

Go to Step 17

16

Check for any of the following conditions that may contribute to the engine overheating:

    • An overloaded vehicle
    • The A/C system
    • Excess engine oil
    • Blocked air flow through the radiator
    • Extreme air temperatures

Does the engine still overheat?

--

--

System OK

17

Replace the radiator fan clutch.

    • Refer to Fan Replacement .
    • Refer to Fan Replacement .
    • Refer to Fan Replacement .

Does the engine still overheat?

--

--

System OK