Hummer H3. Manual — part 1098

Water pump

Are any of the listed components leaking?

Go to Step 20

Go to Step 13

13

1. Pressure test the cooling system. Refer to

Cooling System Leak Testing.

2. With the cooling system pressurized,

visually inspect the components listed in
steps 11 and 12.

Are any leaks present?

Go to Step 20

Go to Step 14

14

Pressure test the coolant pressure cap. Refer
to Pressure Cap Testing.
Does the coolant pressure cap hold pressure?

Go to Step 16

Go to Step 21

15

Pressure test the coolant pressure cap. Refer
to Pressure Cap Testing.
Does the coolant pressure cap hold pressure?

Go to Step 32

Go to Step 21

16

Inspect for the following conditions:

A coolant smell inside of the vehicle

Coolant in the HVAC module drain tube

Coolant on the vehicle floor covering
near the HVAC module

Is coolant present?

Go to Step 22

Go to Step 17

17

Inspect the underside of the engine oil fill cap
for a gray/white milky substance.
Is there a milky substance under the oil fill
cap?

Go to Step 18

Go to Step 19

18

Inspect the engine oil fluid level indicator for
a gray/white milky substance.
Is there a milky substance on the engine oil
fluid level indicator?

Go to Step 23

Go to Step 19

19

Inspect the automatic transmission oil fluid
level indicator, if equipped, for a gray/white
milky substance.
Is there a milky substance on the automatic

2007 Hummer H3

2007 ENGINE Engine Cooling - H3

transmission fluid level indicator?

Go to Step 25

Go to Step 33

20

Repair or replace the leaking component.
Refer to the appropriate repair.
Is the repair complete?

Go to Step 33

-

21

Replace the coolant pressure cap.
Is the repair complete?

Go to Step 33

-

22

Replace the heater core. Refer to Heater
Core Replacement (Left Hand Drive) or
Heater Core Replacement (Right Hand
Drive) .
Is the repair complete?

Go to Step 33

-

23

1. Remove the engine oil cooler lines from

the radiator.

2. Pressure test the cooling system. Refer to

Cooling System Leak Testing.

3. Inspect the engine oil cooler for coolant.

Is coolant present?

Go to Step 24

Go to Step 27

24

1. Replace the radiator. Refer to Radiator

Replacement.

2. Service the engine oil and filter. Refer

to Engine Oil and Oil Filter
Replacement .

Is the repair complete?

Go to Step 33

-

25

1. Remove the transmission oil cooler lines

from the radiator.

2. Pressure test the cooling system. Refer to

Cooling System Leak Testing.

3. Inspect the transmission oil cooler for

coolant.

Is coolant present?

Go to Step 26

Go to Step 27

26

1. Replace the radiator. Refer to Radiator

Replacement.

2. Service the automatic transmission.

2007 Hummer H3

2007 ENGINE Engine Cooling - H3

THERMOSTAT DIAGNOSIS

Thermostat Test Procedure Using Tempilsticks

Refer to Engine Coolant/Water in
Transmission .

Is the repair complete?

Go to Step 33

-

27

Install the cooler lines to the radiator.
Is the action complete?

Go to Step 33

-

28

Repair the engine no crank condition. Refer
to Engine Will Not Crank - Crankshaft
Will Not Rotate .
Is the repair complete?

Go to Step 33

-

29

Repair the engine overheating condition.
Refer to Engine Overheating.
Is the repair complete?

Go to Step 33

-

30

Repair the engine internal coolant leak. Refer
to Coolant in Engine Oil .
Is the repair complete?

Go to Step 33

-

31

Repair the engine knock. Refer to Lower
Engine Noise, Regardless of Engine
Speed .
Is the repair complete?

Go to Step 33

-

32

Repair the combustion pressure in the cooling
system problem. Refer to Cylinder Leakage
Test .
Is the repair complete?

Go to Step 33

-

33

Operate the system in order to verify the
repair.
Did you find and correct the condition?

System OK

Go to Step 2

2007 Hummer H3

2007 ENGINE Engine Cooling - H3

Fig. 1: View Of Radiator Inlet Hose & Thermostat Housing
Courtesy of GENERAL MOTORS CORP.

The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a
pencil like device. It has a wax material containing certain chemicals which melt at a given
temperature. Temperature sticks can be used to determine a thermostat's operating range, by
rubbing 87°C (188°F) and 97°C (206°F) sticks on the thermostat housing (4).

Tools Required

J 24731 Tempilstick. See Special Tools.

2007 Hummer H3

2007 ENGINE Engine Cooling - H3