SsangYong Rexton. Manual - part 56

DI04-37

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

EXHAUST SYSTEM

DI ENG SM - 2004.4

SYSTEM OVERVIEW

Exhaust System

Check the complete exhaust system and the nearby body
areas and trunk lid for broken, damaged, missing or
mispositioned parts, open seams, holes, loose
connections, or other deterioration which could permit
exhaust fumes to seep into the trunk may be an indication
of a problem in one of these areas. Any defects should be
corrected immediately.

Muffler

Aside from the exhaust manifold connection, the exhaust
system uses a flange and seal joint design rather than a
slip joint coupling design with clamp and U-bolts. If hole,
open seams, or any deterioration is discovered upon in-
spection of the front muffler and pipe assembly, the com-
plete assembly should be replace, the complete assem-
bly should be replaced. The same procedure is applicable
to the rear muffler assembly. Heat shields for the front and
rear muffler assembly and catalytic converter protect the
vehicle and the environment from the high temperatures
that the exhaust system develops.

Heat Shield

The heat shield protects the vehicle and components from
the high heat generated from the exhaust system.

In this vehicle, the heat shield to block the heat from DOC
is installed to the underbody, and the heat shield to block
the heat from the rear muffler is installed to the underbody
between the fuel tank and the rear muffler.

Hanger

The hanger is to support the components.

If the ganger is not properly installed, it may cause the
vibration that is very difficult to diagnose. Therefore, install
the hanger to the correct location so that the exhaust sys-
tem cannot contact to the underbody and other
components.

Notice

When you are inspecting or replacing exhaust system
components, make sure there is adequate clearance
from all points on the underbody to avoid possible
overheating of the floor panel and possible damage to
the passenger compartment insulation and trim
materials.

DOC (Diesel Oxidation Catalyst)

DOC (Diesel Oxidation Catalyst) is the purification device
to reduce the toxic emissions from the exhaust gas from
the engine. By using the chemical reaction, the amount of
toxic gas such as NOx can be reduced.

Notice

To prevent damage of DOC, never contact the lift pad
when lifting up the vehicle.

DI04-38

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

EXHAUST SYSTEM

DI ENG SM - 2004.4

Mat

Insulation

Cover

Upper part of

converter

Plate

Monolith catalyst

Lower part of

converter

Inlet gas

Outlet gas

Y220_04040

System and principle

Oxidation catalytic technology for diesel engine is basi-
cally the same with it of gasoline engine used before de-
velopment of 3 primary catalyst (2 primary catalyst), and
its effect and performance were already proved.

DOC (Diesel Oxidation Catalyst) reduces HO and CO con-
tained exhaust gas over 80 %, and removes SOF (Soluble
Organic Fraction) over 50 ~ 80 %, but because its portion
in total PM is low, it reduces approx, 20 ~ 40 % of TPM
(Total Particulate Material).

Because of low reducing rate for PM of DOC, in order to
guarantee safety rate of PM regulation, this technology is
being used mainly. And it should keep over 80% of PM
reducing rate, and at present it plays a role as a transition
stage.

And also it reduces diesel odor and black smoke, plati-
num or palladium are being used as a catalyst.

On the other hand, it is a problem that it makes the reac-
tion of oxidation, which SO

2

 produce SO

3

 and H

2

 SO

4

 by

reacting to oxygen in exhaust gas, if temperature of ex-
haust gas becomes over 300°C, and this produced gas is
very harmful to human body. To prevent is, previously it is
requested that the sulfur content rate of fuel should be
below 0.05 %, and in the future it is being expected to
keep it below 0.01 %.

Catalytic converter structure

The Catalytic converter of monolith type consists of 2 walled
metal bodies which is made of Cordierite.

The principal element of converter consists of the materi-
als like Alumina or oxidized Serume in order to apply to
Ceramic Monolith. Washer coat operates first, and cata-
lytic metal elements (Pt, Pd, Ph) operates to washer coat
next.

Monolith type is lighter than other types, easy to manu-
facture and quickly approaches to proper temperature.

Washer coat is used to make a contact surface with ex-
haust gas bigger by adhering closely to small holes of
inner layer.

If a lead compound or phosphorus adheres to the surface
and the temperature rises, its surface is decreased.

The total area of general monolith converter is about
45,000 ~ 500,000 ft

3

. (10 times of a football field)

Generally Alumina (AL

2

O

3

) is used as a raw material and

its 7 phases of gamma, delta, theta have big areas and
high stability for the temperature, and nowadays gamma
Alumina is used usually.

DOC (Diesel Oxidation Catalyst)

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CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

EXHAUST SYSTEM

DI ENG SM - 2004.4

Purification of catalytic converter

• Adhesion of soluble organic fraction (SOF) below 180°C

• Purification of soluble organic fraction (SOF) over 180°C

Chemical reaction formula

• SOF(HC) + O2 ............... O2 + H2O

• 2CO + O2 ...................... 2CO2

• 2C2H6 + 7O2 ................. 4CO2 + 6H2O

Y220_04043

Y220_04042

Y220_04041

Catalytic converter and temperature

Catalytic converter has the normal function of purification at a
range of the temperature. Because it has a weak point of de-
creasing of the purification rate in the condition of continuous
high temperature, it should keep the temperature range of 400
to 500°C for normal condition. HC purification rate becomes
better according to the increase of temperature in the normal
range of temperature. CO purification rate becomes the best
near the temperature of 450°C, and NOx does so near the
temperature of 400 to 500°C.

• Oxygen adheres to catalytic material : below 180°C

Aldehide

Aromatic HC

Catalytic Material

Catalytic Material

DI04-40

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

EXHAUST SYSTEM

DI ENG SM - 2004.4

Y220_04045

Y220_04044

• Catalytic material supplies each CO and HC with O2 for

their oxidation : above 180°C

Catalytic Material

Catalytic Material

PAH (Aromatic HC)

Catalyzer

• Catalytic material conversion process by DOC

Method for reduction of NOx

NOx is generated a great deal in case that combustion tem-
perature and excess air factor are high. EGR valve can de-
crease NOx (30 to 35 % decrease) by making temperature of
combustion chamber fall by means of exhaust gas re-
circulation.