Hummer H2. Manual — part 1906

Fig. 44: Left Exhaust Heat Shield & Nuts (Dash Panel)
Courtesy of GENERAL MOTORS CORP.

1. Install the exhaust heat shield to the dash panel studs (1), (3).

2. Install the exhaust heat shield nuts.

Tighten: Tighten the nuts to 9 N.m (80 lb in).

3. Install the engine protection shield and bolts. Refer to Engine Protection Shield Replacement in Frame

and Underbody.

NOTE:

Refer to Fastener Notice in Cautions and Notices.

2004 Hummer H2

2004 ENGINE Engine Exhaust - Hummer H2

Tighten: Tighten the bolts to 20 N.m (15 lb ft).

4. Lower the vehicle.

DESCRIPTION AND OPERATION

EXHAUST SYSTEM DESCRIPTION

The exhaust system carries exhaust gases, treated by the catalytic converter, through a resonator, if applicable
and into the exhaust muffler where exhaust noise is lessened.

In order to secure the exhaust pipe to the exhaust manifold, a flange and seal-joint coupling is utilized. The
exhaust system may utilize a slip-joint coupling design with a clamp and a U-bolt or a flange connection with a
gasket.

Exhaust hangers and rubber insulators help to support the weight of the exhaust pipe along with insulating any
exhaust system vibration, rattle, or noise.

Exhaust hangers also space the exhaust system away from the underbody of the vehicle and allows the exhaust
system to expand as the exhaust system warms up.

Exhaust heat shields are used to protect the body and other components from damage due to the heat from the
exhaust system.

The exhaust system may be comprised of the following components:

z

Exhaust manifold

z

Exhaust pipes

z

Catalytic converters

z

Exhaust muffler

z

Exhaust resonator, if equipped

z

Exhaust tail pipe, if equipped

z

Exhaust hangers

z

Exhaust heat shields

Resonator

Some exhaust systems are equipped with a resonator. The resonator, located either before or after the muffler,
allows the use of mufflers with less back pressure. Resonators are used when vehicle characteristics require
specific exhaust tuning.

Catalytic Converter

IMPORTANT: Use of non-OEM parts may cause driveability concerns.

2004 Hummer H2

2004 ENGINE Engine Exhaust - Hummer H2

The catalytic converter is an emission control device added to the engine exhaust system in order to reduce
hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) pollutants from the exhaust gas.

The catalytic converter is comprised of a ceramic monolith substrate, supported in insulation and housed within
a sheet metal shell. The substrate may be washcoated with 3 noble metals:

z

Platinum (Pt)

z

Palladium (Pd)

z

Rhodium (Rh)

The catalyst in the converter is not serviceable.

Muffler

The exhaust muffler reduces the noise levels of the engine exhaust by the use of tuning tubes. The tuning tubes
create channels inside the exhaust muffler that lower the sound levels created by the combustion of the engine.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Special Tools

Illustration

Tool Number/Description

J 35314-A/BT-8515/BT-8515A

Exhaust Back Pressure Tester

J 38185

Hose Clamp Pliers

2004 Hummer H2

2004 ENGINE Engine Exhaust - Hummer H2

J 43181

Heater Line Quick Connect Release Tool

2004 Hummer H2

2004 ENGINE Engine Exhaust - Hummer H2