GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Inspect the radiator for stains and wetness.

Are there any stains or is there any wetness on the radiator?

--

Go to Step 2

Go to Step 3

2

Repair as necessary.

Is there still a coolant loss?

--

Go to Step 3

Go to Step 16

3

Inspect the coolant hoses for stains and wetness.

Are there any stains or is there any wetness on the coolant hoses?

--

Go to Step 4

Go to Step 5

4

Repair as necessary.

Is there still a loss of coolant?

--

Go to Step 5

Go to Step 16

5

Inspect the water pump for stains and wetness.

Are there any stains or is there any wetness on the water pump?

--

Go to Step 6

Go to Step 7

6

Repair as necessary.

Is there still a loss of coolant?

--

Go to Step 9

Go to Step 16

7

Inspect the heater core for stains and wetness.

Are there any stains or wetness on the heater core?

--

Go to Step 8

Go to Step 9

8

Repair as necessary.

Is there still a loss of coolant?

--

Go to Step 9

System OK

9

Inspect the coolant recovery reservoir or surge tank for leakage.

Does the coolant overflow from the reservoir with the engine off?

--

Go to Step 10

Go to Step 15

10

Inspect the radiator cap for proper pressure retention.

Does the radiator cap maintain the correct pressure?

103 kPa (15 psi)

Go to Step 11

Go to Step 12

11

Inspect the temperature reading of the thermostat. Refer to Thermostat Diagnosis .

Is the temperature too high?

--

Go to Engine Overheating

Go to Step 13

12

Replace the radiator cap.

Is there still a coolant loss?

--

Go to Step 13

--

13

Inspect the coolant concentration.

Is the coolant concentration too low?

--

Go to Step 14

Go to Step 16

14

Notice: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

Replace the coolant with the proper mixture of DEX-COOL™.

Is there still a coolant loss?

--

Go to Step 1

Go to Step 16

15

Test for a coolant leak inside the engine.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 1

16

Retest the cooling system for leaks.

Is there a coolant loss?

--

Go to Step 1

System OK