GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Inspect for a leaking radiator. Refer to Cooling System Leak Testing .

Is the radiator leaking?

Go to Step 2

Go to Step 3

2

Repair or install new parts as necessary.

Is the repair complete?

System OK

--

3

Inspect for a leaking heater core. Refer to Cooling System Leak Testing .

Is the heater core leaking?

Go to Step 2

Go to Step 4

4

Inspect for a faulty surge tank pressure cap.

Is the cap operating properly?

Go to Step 5

Go to Step 2

5

Inspect for a leaking coolant recovery hose or a cracked surge tank. Refer to Surge Tank Replacement .

Is the reservoir or the hose leaking?

Go to Step 2

Go to Step 6

6

Inspect for any loose or damaged hoses or connections.

Are any hoses damaged or are any hose connections leaking?

Go to Step 2

Go to Step 7

7

Inspect for a cracked thermostat housing or a leaking thermostat seal. Refer to Engine Coolant Thermostat Replacement .

Is the thermostat housing cracked or is there a seal leak?

Go to Step 2

Go to Step 8

8

Inspect for a cracked water pump or a leaking water pump gasket.

Is the water pump cracked or is there a leaking gasket?

Go to Step 2

Go to Step 9

9

Inspect for a leaking water pump driveshaft seal.

Is the water pump shaft seal leaking?

Go to Step 10

Go to Step 11

10

Replace the water pump. Refer to Water Pump Replacement .

Is the repair complete?

System OK

Go to Step 11

11

Inspect for a leaking engine block coolant drain hole plug.

Are any drain hole plugs leaking?

Go to Step 2

Go to Step 12

12

Inspect for any leaking cylinder head core plugs.

Are the cylinder head core plugs leaking?

Go to Step 2

Go to Step 13

13

Inspect for a leaking cylinder head gaskets, vents or a cracked cylinder heads. Refer to Cylinder Head Replacement in Engine Mechanical.

Is the cylinder head gasket leaking or is the cylinder head cracked?

Go to Step 2

Go to Step 14

14

Inspect for a cracked throttle body or a gasket leak.

Is the throttle body cracked or is there a gasket leak?

Go to Step 2

Go to Step 15

15

Inspect for a cracked cylinder block.

Is the cylinder block cracked?

Go to Step 2

Go to Step 16

16

Inspect for any porous castings.

Are the castings OK?

System OK