Hummer H3. Manual — part 1100

Fig. 3: Pressure Testing Cooling System Using J 24460-01
Courtesy of GENERAL MOTORS CORP.

3. Use the J 24460-01 in order to apply pressure to the cooling system. See Special Tools.

Do not exceed the pressure cap rating.

4. The cooling system should hold the rated pressure for at least 2 minutes.

Observe the gage for any pressure loss.

5. Repair any leaks as required.

FAN CLUTCH DIAGNOSIS

Fan Clutch Diagnosis

Step

Action

Yes

No

2007 Hummer H3

2007 ENGINE Engine Cooling - H3

DEFINITION: Testing the engagement and disengagement of the fan clutch.

1

Were you sent here from Symptoms or
another diagnostic table?

Go to Step 2

Go to
Symptoms -
Engine Cooling

2

Is there excessive fan air noise?

Go to Step 3

Go to Step 4

3

Fan air noise is normal during cold engine
start up.
Does the fan noise go away at normal
engine operating temperature?

Go to Step 13

Go to Step 4

4

Rotate the fan clutch.Does the fan clutch
rotate?

IMPORTANT:

The engine must be turned off and the engine
temperature should be cold.

Go to Step 5

Go to Step 14

5

Visually inspect the fan blades for cracks,
looseness or damage.
Are the fan blades in good condition?

Go to Step 6

Go to Step 15

6

Visually inspect the fan clutch for signs of
silicone leakage.

Slight silicone leakage may not effect
the fan clutch engagement.

Excessive leakage will prevent the
fan clutch from engaging.

Is the silicone fluid leakage excessive?

Go to Step 14

Go to Step 7

7

Inspect the fan clutch for proper
installation.

1. Move the fan blade back and forth in

a lateral motion.

2. Inspect for fan blade to fan clutch

movement.

Is the fan blade loose at the fan clutch?

Go to Step 10

Go to Step 8

Inspect the fan clutch for wear.

2007 Hummer H3

2007 ENGINE Engine Cooling - H3

8

1. Move the fan blade back and forth in

a lateral motion.

2. Inspect for fan clutch lateral

movement.

Is the fan clutch lateral movement
excessive?

IMPORTANT:

Approximately 6.5 mm (1/4 in)
movement at the tip of the fan blade is
normal.

Go to Step 14

Go to Step 9

9

The fan clutch should have more turning
resistance when the engine is at or above
normal operating temperature.
Does the fan clutch have more resistance
when the engine temperature is raised?

Go to Step 11

Go to Step 14

10

Tighten the fan. Refer to Fastener
Tightening Specifications.
Is the repair complete?

Go to Step 16

-

Perform a fan clutch engagement test.

1. Ensure the engine coolant level is

full.

2. Ensure the cooling fan drive belt

tension is correct and not slipping.

3. Position and secure a thermometer

between the fan clutch and the
radiator.

4. Ensure the cooling fan is disengaged

before starting this test.

5. Sufficiently cover the radiator grille

to restrict the air flow.

IMPORTANT:

Do not allow engine temperature to
exceed 121°C (250°F).

2007 Hummer H3

2007 ENGINE Engine Cooling - H3

11

6. Start the engine.

7. Turn the A/C ON, if equipped.

8. Operate the engine at approximately

2,000 RPM.

9. Note the thermometer reading when

the fan clutch engages.

10. Do not continue this test if the fan

clutch does not engage between 85-
96°C (185-205°F).

Fan clutch engagement will be indicated
by an increase in fan air noise, fan speed
and a temperature drop of about 3-10°C
(5-15°F) on the thermometer.
Did the fan clutch engage between 85-96°
C (185-205°F)?

Go to Step 12

Go to Step 14

12

Once the fan clutch engages, perform the
following steps:

1. Uncover the radiator grille.

2. Turn the A/C OFF, if equipped.

3. Operate the engine at approximately

2,500 RPM to reduce the engine
operating temperature.

4. Remove the thermometer.

Did the engine return to normal operating
temperature?

Go to Step 13

-

13

As the engine temperature returns to
normal, the fan clutch will disengage,
indicated by a reduction in fan air noise
and fan speed.
Did the fan clutch disengage?

Go to Step 16

Go to Step 14

14

Replace the fan clutch. Refer to Fan
Clutch Replacement.

2007 Hummer H3

2007 ENGINE Engine Cooling - H3