GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Check for an incorrect or faulty surge tank cap.

Is the surge tank cap incorrect or faulty?

--

Go to Step 2

Go to Step 3

2

Replace the surge tank cap.

Is there still a coolant loss?

103 kPa (15 psi)

Go to Step 3

System OK

3

  1. Check for any loose or damaged coolant hoses.
  2. Check the hose connections.

Are any hoses loose or damaged?

--

Go to Step 4

Go to Step 5

4

  1. Reseat or retighten the clamps properly on the hoses and the connections.
  2. Replace the clamp and the hose if necessary.

Is there still a coolant loss?

--

Go to Step 5

System OK

5

Check the surge tank and tank hose for any leaks.

Is the surge tank hose or tank leaking?

--

Go to Step 6

Go to Step 7

6

Replace the surge tank hose or the surge tank.

Is there still a coolant loss?

--

Go to Step 7

System OK

7

Check the cylinder head bolts for the proper torque.

Are the bolts tightened to the proper specification?

--

Go to Step 8

Go to Step 9

8

Check for a seal leak at the water pump.

Is there a seal leak at the water pump?

--

Go to Step 10

Go to Step 11

9

Tighten the cylinder head bolts to the proper specification.

Is there still a coolant leak?

--

Go to Step 10

System OK

10

Replace the coolant pump.

Is there still a coolant loss?

--

Go to Step 11

System OK

11

Check for a coolant pump gasket leak.

Is the coolant pump gasket leaking?

--

Go to Step 12

Go to Step 13

12

Replace the coolant pump gasket.

Is there still a coolant loss?

--

Go to Step 13

System OK

13

Check for a leak at the cylinder head gasket.

Is there coolant leakage at the cylinder head gasket?

--

Go to Step 14

Go to Step 15

14

Replace the cylinder head gasket. Refer to Cylinder Head Replacement in Engine Mechanical.

Is there still a coolant loss?

--

Go to Step 15

System OK

15

Check for coolant leakage at the radiator. Pressure test the cooling system.

Is there coolant leakage at the radiator?

--

Go to Step 16

Go to Step 17

16

Replace the radiator.

Is there still a coolant loss?

--

Go to Step 17

System OK

17

Check the heater core for leakage.

Is the heater core leaking?

--

Go to Step 18

Go to Step 19

18

Replace the heater core.

Is there still a loss of coolant?

--

Go to Step 19

System OK

19

Check for cracked cylinder head or block. Perform a cylinder leak test.

Is the cylinder head or block cracked?

--

Go to Step 20

System OK

20

Replace the cylinder head or block.

Is there still a coolant loss?

--

Go to Step 1

System OK