Hummer H3. Manual — part 1157

4

Sensor 1 Replacement .

2. Install the J 35314-A Exhaust

Back Pressure Gage in place of
the HO2S sensor. See Special
Tools.

3. Start the engine.

4. Increase and monitor the

engine speed at 2,500 RPM.

5. Observe the exhaust system

back pressure reading on the
gage.

Does the reading exceed the
specified value?

9 kPa (1.25

psi)

Go to Step 5 Go to Step 8

5

1. Turn the engine off and place

the ignition in the lock
position.

2. Remove the J 35314-A . See

Special Tools.

3. Re-install the HO2S sensor.

Refer to Heated Oxygen
Sensor 1 Replacement .

4. Remove the post-catalyst

HO2S sensor. Refer to Heated
Oxygen Sensor 2
Replacement .

5. Install the J 35314-A in place

of the post HO2S sensor. See
Special Tools.

6. Start the engine.

7. Increase and monitor the

engine speed at 2,500 RPM.

8. Observe the exhaust system

back pressure reading on the
gage.

Does the reading exceed the

9 kPa (1.25

psi)

2007 Hummer H3

2007 ENGINE Engine Exhaust - H3

EXHAUST LEAKAGE

Exhaust Leakage

specified value?

Go to Step 6 Go to Step 7

6

Inspect the exhaust system for the
following conditions:

Damage in the exhaust pipe

Debris in the exhaust pipe

Muffler or resonator internal
failure

Two-layer exhaust pipe
separation

Did you find and correct the
condition?

-

Go to Step 8

-

7

Replace the catalytic converter.
Refer to Catalytic Converter
Replacement.
Did you find and correct the
condition?

-

Go to Step 8

-

8

1. Remove the J 35314-A . See

Special Tools.

2. Reinstall the applicable HO2S

sensor. Refer to the following:

Heated Oxygen Sensor
1 Replacement

Heated Oxygen Sensor
2 Replacement

3. Clear any codes.

4. Road test the vehicle in order

to verify the repair.

Did you correct the condition?

-

System OK Go to Step 2

Condition

Action

2007 Hummer H3

2007 ENGINE Engine Exhaust - H3

DEFINITION: An exhaust leak may show stains at the area of the leak. The leak may be
felt by holding a hand close to the suspected areas or using a smoke pencil. The leak may
make a popping or hissing noise.Refer to Symptoms - Engine Exhaust prior to beginning
this table.

CAUTION:

Refer to Hot Exhaust System Caution .

Misaligned or improperly
installed exhaust system
components

Align and tighten the exhaust system components to the
specifications. Refer to Fastener Tightening
Specifications.

Ensure the exhaust hangers are in the proper locations
and not loose. Refer to Exhaust System Insulator,
Hanger, Bracket Replacement.

Exhaust leaks at the
following connections:

Exhaust manifold to
pipe

Flanges

Pipe clamps

Tighten the components to the specifications. Refer to
Fastener Tightening Specifications.

Seals or gaskets leaking:

Exhaust manifold to
cylinder head

Catalytic converter to
exhaust manifold

Catalytic converter to
muffler

Replace the leaking seal or gasket. Refer to the following:

Exhaust Manifold Replacement

Exhaust Seal Replacement

Irregularities at the mating
surfaces on the flange
connections

Repair as required or replace the affected component. Refer
to the affected components procedure for service.

Exhaust manifold cracked or
broken

Replace the exhaust manifold. Refer to Exhaust Manifold
Replacement.

Exhaust system component
connection welds leaking

Replace the leaking component. Refer to the affected
component's procedure for service.

Muffler or resonator, if
equipped, damaged or

Replace the affected muffler or resonator, if equipped. Refer
to Muffler Replacement.

2007 Hummer H3

2007 ENGINE Engine Exhaust - H3

EXHAUST NOISE

Exhaust Noise

REPAIR INSTRUCTIONS

EXHAUST MANIFOLD REPLACEMENT

Removal Procedure

leaking at the seams

Condition

Action

DEFINITION: An audible or physical noise due to a faulty component or damaged
components causing a loose or misaligned exhaust system resulting in a rattle or vibration
noise.

CAUTION:

Refer to Hot Exhaust System Caution .

IMPORTANT:

Refer to Symptoms - Engine Exhaust prior to beginning this table.

Popping or hissing noise

Exhaust leak. Refer to Exhaust Leakage.

Loud exhaust

1. Compare to a known good vehicle.

2. Inspect for a damaged or failed muffler.

3. Replace the faulty muffler. Refer to Muffler

Replacement.

External rattle or vibration noise

1. Inspect for a bent or loose hanger, loose heat shield

or loose clamp.

2. Inspect for a exhaust pipe causing interference.

3. Repair or replace the affected component. Refer to

the affected component's service procedure.

Internal rattle

1. Test the components by tapping with a rubber mallet

to confirm a rattle.

2. Replace the faulty catalytic converter, resonator or

muffler. Refer to one of the following procedures:

Catalytic Converter Replacement

Muffler Replacement

2007 Hummer H3

2007 ENGINE Engine Exhaust - H3