Hummer H3. Manual — part 490

5. Inspect for the following conditions:

Oil diluted by water or glycol antifreeze

Refer to Coolant in Engine Oil .

Foamy oil, which may be caused by a cut or damaged oil pump screen O-ring seal

6. Remove the oil filter and install the EN-47971 (1). See Special Tools.

7. Install the J 21867 (2), or equivalent to the EN-47971 (1). See Special Tools.

8. Run the engine and measure the engine oil pressure.

9. Compare the readings to Engine Mechanical Specifications.

10. If the engine oil pressure is below specifications, inspect the engine for 1 or more of the

following conditions:

Oil pump worn or dirty

Refer to Oil Pump Cleaning and Inspection .

Oil pump-to-engine block bolts loose

Refer to Oil Pump, Screen and Crankshaft Oil Deflector Installation .

Oil pump screen loose, plugged, or damaged

Oil pump screen O-ring seal missing or damaged

Malfunctioning oil pump pressure relief valve

Excessive bearing clearance

Cracked, porous, or restricted oil galleries

Oil gallery plugs missing or incorrectly installed

Refer to Engine Block Plug Installation .

OIL LEAK DIAGNOSIS

Step

Action

Yes

No

IMPORTANT:

You can repair most fluid leaks by first visually locating the leak, repairing or replacing the
component, or by resealing the gasket surface. Once the leak is identified, determine the cause of
the leak. Repair the cause of the leak as well as the leak itself.

1. Operate the vehicle until it reaches normal

2008 Hummer H3

2008 ENGINE Engine Mechanical - 5.3L - H3

1

operating temperature.

2. Park the vehicle on a level surface, over a

large sheet of paper or other clean surface.

3. Wait 15 minutes.

4. Inspect for drippings.

Are drippings present?

Go to Step 2

System OK

2

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 3

3

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 4

4

1. Completely clean the entire engine and

surrounding components.

2. Operate the vehicle for several kilometers,

miles, at normal operating temperature and
at varying speeds.

3. Park the vehicle on a level surface, over a

large sheet of paper or other clean surface.

4. Wait 15 minutes.

5. Identify the type of fluid, and the

approximate location of the leak.

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 5

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

2008 Hummer H3

2008 ENGINE Engine Mechanical - 5.3L - H3

5

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 6

6

1. Completely clean the entire engine and

surrounding components.

2. Apply an aerosol-type powder, baby

powder, foot powder, etc., to the suspected
area.

3. Operate the vehicle for several kilometers,

miles, at normal operating temperature and
at varying speeds.

4. Identify the type of fluid, and the

approximate location of the leak, from the
discolorations in the powder surface.

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 7

7

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 8

8

Use the J 28428-E high-intensity black light kit
in order to identify the type of fluid, and the
approximate location of the leak. Refer to the
manufacturer's instructions when using the tool.
Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 9

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2008 ENGINE Engine Mechanical - 5.3L - H3

9

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

System OK

10

1. Inspect the engine for mechanical damage.

Special attention should be shown to the
following areas:

Higher than recommended fluid levels

Higher than recommended fluid
pressures

Plugged or malfunctioning fluid filters
or pressure bypass valves

Plugged or malfunctioning engine
ventilation system

Improperly tightened or damaged
fasteners

Cracked or porous components

Improper sealants or gaskets, where
required

Improper sealant or gasket installation

Damaged or worn gaskets or seals

Damaged or worn sealing surfaces

2. Inspect the engine for customer

modifications.

Is there mechanical damage, or customer
modifications to the engine?

Go to Step 11

System OK

11

Repair or replace all damaged or modified
components.
Does the engine still leak oil?

Go to Step 1

System OK

2008 Hummer H3

2008 ENGINE Engine Mechanical - 5.3L - H3