GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Cooling

2

  1. Ensure that the cooling system is full. Refer to Cooling System Draining and Filling .
  2. Start the engine and inspect.

Is there excessive white smoke from the exhaust and/or does the engine run rough?

Go to Step 7

Go to Step 3

3

Allow the engine to reach operating temperature.

Does the engine overheat?

Go to Engine Overheating

Go to Step 4

4

Remove the oil level indicator stick and inspect.

Is there engine coolant or a creamy/milky substance on the engine oil level indicator?

Go to Step 5

Go to Step 6

5

Important: Ensure that the creamy or milky substance is not caused by short drive cycles or a faulty thermostat. Either of these conditions will cause creamy or milky deposits to form in the engine oil because the engine cannot reach full operating temperature in order to dissipate the condensation/moisture.

Does the engine reach full operating temperature during all of the vehicle drive cycles and does the thermostat operate properly?

Go to Step 7

Go to Step 6

6

  1. Pressure test the cooling system.
  2. While the cooling system is pressurized, inspect for a coolant leak.
  3. Repair or replace the leaking component(s) as necessary.

Did you complete the repair?

Go to Step 8

--

7

The probable cause of the coolant loss is an engine internal coolant leak.

If the spark plug electrodes or the porcelain surrounding the spark plug electrodes exhibit signs of coolant, replace the intake manifold/gasket or the applicable cylinder head/gasket(s) as necessary.

Did you complete the repair?

Go to Step 8

--

8

  1. Ensure that the cooling system is full. Refer to Cooling System Draining and Filling .
  2. Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2