EXHAUST SYSTEM
TABLE OF CONTENTS
page page
EXHAUST SYSTEM
DESCRIPTION............................1
OPERATION.............................1
DIAGNOSIS AND TESTING..................2
EXHAUST SYSTEM......................2
EXHAUST SYSTEM RESTRICTION CHECK....2
INSPECTION.............................3
ADJUSTMENTS...........................3
SPECIFICATIONS.........................3
CATALYTIC CONVERTER
DESCRIPTION............................4
OPERATION.............................4
REMOVAL...............................4
INSPECTION.............................5
INSTALLATION............................5CROSS-OVER PIPE
REMOVAL...............................6
INSTALLATION............................6
HEAT SHIELDS
DESCRIPTION............................6
OPERATION.............................6
REMOVAL...............................7
INSTALLATION............................7
MUFFLER
REMOVAL...............................7
INSTALLATION............................7
RESONATOR
REMOVAL...............................8
INSTALLATION............................8
EXHAUST SYSTEM
DESCRIPTION
The exhaust system consist of a catalytic converter,
muffler, and a resonator with connecting pipes in-be-
tween (Fig. 1). The system is serviced in two sections;
the catalytic converter and pipe, and the muffler and
resonator with connecting pipe. A band clamp is used
to connect the joint between the two components.
Three support hanger rods with rubber isolators areused to support and isolate the exhaust system. A
flexible joint, integral to the catalytic converter,
allows for engine movement. On vehicles equipped
with AWD, an additional heat shield is mounted to
the catalytic converter. The exhaust system is tuned
for each vehicle/powertrain combination.
OPERATION
The exhaust system contains, quiets, and cleans
the exhaust gases generated by the engine.
Fig. 1 Exhaust System - Typical (All Vehicles)
1 - CATALYTIC CONVERTER
2 - BAND CLAMP
3 - SUPPORTS - MUFFLER
4 - SUPPORT - RESONATOR5 - RESONATOR
6 - MUFFLER
RSEXHAUST SYSTEM11-1
DIAGNOSIS AND TESTING - EXHAUST SYSTEM
CONDITION POSSIBLE CAUSES CORRECTION
EXCESSIVE EXHAUST NOISE
(UNDER HOOD)1. Exhaust manifold cracked or
broken.1. Replace manifold.
2. Manifold to cylinder head leak. 2. Tighten manifold and/or replace
gasket.
3. EGR Valve to manifold gasket
leakage.3. Tighten fasteners or replace
gasket.
4. EGR Valve to EGR tube gasket
leakage.4. Tighten fasteners or replace
gasket.
5. EGR tube to manifold tube
leakage.5. Tighten tube nut.
6. Exhaust flex-joint to manifold
leak.6. Tighten joint fasteners and/or
replace gasket.
7. Exhaust flex-joint. 7. Replace catalytic converter
assembly.
8. Pipe and shell noise from front
exhaust pipe.8. Characteristic of single wall pipe.
EXCESSIVE EXHAUST NOISE 1. Leak at exhaust pipe joints. 1. Tighten clamps at leaking joints.
2. Burned or rusted out muffler
assembly or exhaust pipe.2. Replace muffler resonator tailpipe
assembly or exhaust pipe with
catalytic converter assembly.
3. Burned or rusted out resonator. 3. Replace muffler resonator tailpipe
assembly.
4. Restriction in exhaust system. 4. Perform exhaust restriction test.
replace component as necessary.
5. Converter material in muffler. 5. Replace muffler and converter
assemblies. Check fuel injection and
ignition systems for proper
operation.
DIAGNOSIS AND TESTING - EXHAUST SYSTEM
RESTRICTION
Exhaust system restriction can be checked by mea-
suring back pressure using the DRB IIItand PEP
module pressure tester.
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER WORK AROUND OR ATTEMPT
TO SERVICE ANY PART OF THE EXHAUST SYSTEM
UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE
TAKEN WHEN WORKING NEAR THE CATALYTIC
CONVERTER. THE TEMPERATURE OF THE CON-
VERTER RISES TO A HIGH LEVEL AFTER A SHORT
PERIOD OF ENGINE OPERATION TIME.
(1) Disconnect and remove the upstream (before
catalytic converter) oxygen sensor. (Refer to 14 -FUEL SYSTEM/FUEL INJECTION/O2 SENSOR -
REMOVAL)
(2) Install the Exhaust Back Pressure Fitting
Adaptor CH8519.
(3) Connect the Low Pressure Sensor (15 psi)
CH7063 to the back pressure fitting.
(4) Following the PEP module instruction manual,
connect all required cables to the DRB IIItand PEP
module. Select the available menu options on the
DRBIIItdisplay screen for using the digital pressure
gauge function.
(5) Apply the park brake and start the engine.
(6) With transmission in Park or Neutral, raise
engine speed to 2000 RPM. Monitor the pressure
readings on the DRBIIIt. Back pressure should not
exceed specified limit. Refer to specification in table
below EXHAUST BACK PRESSURE LIMITS .
11 - 2 EXHAUST SYSTEMRS
EXHAUST SYSTEM (Continued)
CATALYTIC CONVERTER
DESCRIPTION
The toe board three-way catalytic converter is con-
nected to the exhaust manifold by the use of flex
joint and a gasket. The outlet connects to the muffler
inlet pipe and is secured with a band type clamp
(Fig. 1).
The exhaust flex-joint coupling (Fig. 3) is used to
secure the catalytic converter to the exhaust mani-
fold. The flex-joint has four bolts, four flag nuts and
a gasket that are separate parts from the exhaust
flex-joint. The flex-joint is welded to the catalytic
converter.
CAUTION: When servicing, care must be exercised
not to dent or bend the bellows or bellows cover of
the flex-joint. Should this occur, the flex-joint will
eventually fail and require the catalytic converter be
replaced.
OPERATION
The three-way catalytic converter simultaneously
converts three exhaust emissions into harmless
gases. Specifically, HC and CO emissions are con-
verted into water (H2O) and carbon dioxide (CO2).
Oxides of Nitrogen (NOx) are converted into elemen-
tal Nitrogen (N) and water. The three-way catalyst is
most efficient in converting HC, CO and NOx at the
stoichiometric air fuel ratio of 14.7:1.
The oxygen content in a catalyst is important for
efficient conversion of exhaust gases. When a high
oxygen content (lean) air/fuel ratio is present for an
extended period, oxygen content in a catalyst canreach a maximum. When a rich air/fuel ratio is
present for an extended period, the oxygen content in
the catalyst can become totally depleted. When this
occurs, the catalyst fails to convert the gases. This is
known as catalyst9punch through.9
Catalyst operation is dependent on its ability to
store and release the oxygen needed to complete the
emissions-reducing chemical reactions. As a catalyst
deteriorates, its ability to store oxygen is reduced.
Since the catalyst's ability to store oxygen is some-
what related to proper operation, oxygen storage can
be used as an indicator of catalyst performance.
Refer to the appropriate Powertrain Diagnostic Pro-
cedure for diagnosis of a catalyst related Diagnostic
Trouble Code (DTC).
The combustion reaction caused by the catalyst
releases additional heat in the exhaust system, caus-
ing temperature increases in the area of the reactor
under severe operating conditions. Such conditions
can exist when the engine misfires or otherwise does
not operate at peak efficiency.Do notremove spark
plug wires from plugs or by any other means short
out cylinders, if exhaust system is equipped with a
catalytic converter. Failure of the catalytic converter
can occur due to temperature increases caused by
unburned fuel passing through the converter. This
deterioration of the catalyst core can result in exces-
sively high emission levels, noise complaints, and
exhaust restrictions.
The use of catalysts also involves some non-auto-
motive problems. Unleaded gasoline must be used to
avoid poisoning the catalyst core. Do not allow engine
to operate above 1200 RPM in neutral for extended
periods over 5 minutes. This condition may result in
excessive exhaust system/floor pan temperatures
because of no air movement under the vehicle.
The flex joint allows flexing as the engine moves,
preventing breakage that could occur from the back-
and-forth motion of a transverse mounted engine.
CAUTION: Due to exterior physical similarities of
some catalytic converters with pipe assemblies,
extreme care should be taken with replacement
parts. There are internal converter differences
required in some parts of the country (particularly
vehicles built for States with strict emission
requirements) and between model years.
REMOVAL
(1) Loosen clamp and disconnect the muffler/reso-
nator assembly from catalytic converter pipe.
(2) Disconnect downstream oxygen sensor electri-
cal connector (Fig. 4). For removal of downstream
oxygen sensor, (Refer to 14 - FUEL SYSTEM/FUEL
INJECTION/O2 SENSOR - REMOVAL).
Fig. 3 Flex-joint
1 - FLANGE
2 - END CAPS
3 - CATALYTIC CONVERTER
4 - FLEXIBLE BELLOWS
11 - 4 EXHAUST SYSTEMRS
(3) Remove catalytic converter to exhaust manifold
attaching fasteners (Fig. 5).
(4) Remove catalytic converter and gasket (Fig. 5).
INSPECTION
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER ATTEMPT TO SERVICE ANY
PART OF THE EXHAUST SYSTEM UNTIL IT IS
COOLED. SPECIAL CARE SHOULD BE TAKEN
WHEN WORKING NEAR THE CATALYTIC CON-
VERTER. THE TEMPERATURE OF THE CONVERTER
RISES TO A HIGH LEVEL AFTER A SHORT PERIOD
OF ENGINE OPERATION TIME.
Check catalytic converter for a flow restriction.
(Refer to 11 - EXHAUST SYSTEM - DIAGNOSIS
AND TESTING) Exhaust System Restriction Check
for procedure.
Visually inspect the catalytic converter element by
using a borescope or equivalent. Remove both oxygen
sensors and insert borescope. If borescope is not
available, remove converter and inspect element
using a flashlight. Inspect element for cracked or
melted substrate.
NOTE: Before replacing a catalytic converter, deter-
mine the root cause of failure. Most catalytic con-
verter failures are caused by air, fuel or ignition
problems. (Refer to Appropriate Diagnostic Informa-
tion) for test procedures.
INSTALLATION
(1) Position new gasket onto the manifold flange
and install catalytic converter (Fig. 5). Tighten fas-
teners to 37 N´m (325 in. lbs.).
NOTE: Be careful not to twist or kink the oxygen
sensor wires.
(2) Install (if removed) and connect the down-
stream oxygen sensor (Fig. 4).
(3) Install the muffler/resonator assembly. (Refer
to 11 - EXHAUST SYSTEM/MUFFLER - INSTALLA-
TION)
Fig. 4 Downstream Oxygen Sensor
1 - OXYGEN SENSOR CONNECTOR
2 - CATALYTIC CONVERTER
3 - DOWNSTREAM OXYGEN SENSOR
4 - ENGINE HARNESS CONNECTOR
Fig. 5 Catalytic Converter to Exhaust Manifold
1 - FLAG NUT
2 - GASKET
3 - BOLT
4 - CATALYTIC CONVERTER
RSEXHAUST SYSTEM11-5
CATALYTIC CONVERTER (Continued)
EXHAUST SYSTEM AND TURBOCHARGER
TABLE OF CONTENTS
page page
EXHAUST SYSTEM AND TURBOCHARGER
DESCRIPTION............................1
SPECIFICATIONS.........................1
TURBOCHARGER SYSTEM
DESCRIPTION............................2
OPERATION.............................2
TURBOCHARGER
REMOVAL...............................4CLEANING...............................5
INSTALLATION............................5
HEAT SHIELDS
REMOVAL...............................5
INSTALLATION............................6
EXHAUST SYSTEM AND
TURBOCHARGER
DESCRIPTION
The basic exhaust system consists of an engine
exhaust manifold, turbocharger, exhaust down pipe,
exhaust pipe, exhaust heat shield(s), muffler and
exhaust tailpipe
The exhaust system uses a single muffler.
The exhaust system must be properly aligned to
prevent stress, leakage and body contact. If the sys-
tem contacts any body panel, it will transfer objec-
tionable noises originating from the engine to the
body.
When inspecting an exhaust system, critically
inspect for cracked or loose joints, stripped screw orbolt threads, corrosion damage and worn, cracked or
broken hangers. Replace all components that are
badly corroded or damaged. DO NOT attempt to
repair.
When replacement is required, use original equip-
ment parts (or equivalent). This will assure proper
alignment and provide acceptable exhaust noise lev-
els.
CAUTION: Avoid application of rust prevention com-
pounds or undercoating materials to exhaust sys-
tem floor pan exhaust heat shields. Light overspray
near the edges is permitted. Application of coating
will result in excessive floor pan temperatures and
objectionable fumes.
SPECIFICATIONS
SPECIFICATIONS - TORQUE
2.5L DIESEL - TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Turbocharger Oil Feed
Line Fitting24.5 18 215
Exhaust Manifold Nuts 32.4 24 Ð
Exhaust Manifold Heat
shield Bolts27.5 21 Ð
Turbocharger Downpipe
Nuts32.4 24 Ð
Turbocharger Bracket
Bolts47.1 35 Ð
Turbocharger to Exhaust
Manifold Nuts32.4 24 Ð
RGEXHAUST SYSTEM AND TURBOCHARGER11a-1
TURBOCHARGER SYSTEM
DESCRIPTION
CAUTION: The turbocharger is a performance part
and must not be tampered with. The wastegate
bracket is an integral part of the turbocharger. Tam-
pering with the wastegate components can reduce
durability by increasing cylinder pressure and ther-
mal loading due to incorrect inlet and exhaust man-
ifold pressure. Poor fuel economy and failure to
meet regulatory emissions laws may result. Increas-
ing the turbocharger boost WILL NOT increase
engine power.
The turbocharger is an exhaust-driven super-
charger which increases the pressure and density of
the air entering the engine. With the increase of air
entering the engine, more fuel can be injected into
the cylinders, which creates more power during com-
bustion.
The turbocharger assembly consists of four (4)
major component systems (Fig. 1) (Fig. 2):
²Turbine section
²Compressor section
²Bearing housing
²Wastegate
OPERATION
Exhaust gas pressure and energy drive the tur-
bine, which in turn drives a centrifugal compressor
that compresses the inlet air, and forces the air into
the engine through the charge air cooler and plumb-
ing. Since heat is a by-product of this compression,
the air must pass through a charge air cooler to cool
the incoming air and maintain power and efficiency.
Increasing air flow to the engine provides:
²Improved engine performance
²Lower exhaust smoke density
²Improved operating economy
²Altitude compensation
²Noise reduction.
The turbocharger also uses a wastegate (Fig. 3),
which regulates intake manifold air pressure and
prevents over boosting at high engine speeds. When
the wastegate valve is closed, all of the exhaust gases
flow through the turbine wheel. As the intake mani-
fold pressure increases, the wastegate actuator opens
the valve, diverting some of the exhaust gases away
from the turbine wheel. This limits turbine shaft
speed and air output from the impeller.
Fig. 1 Turbocharger Operation
1 - TURBINE SECTION
2 - EXHAUST GAS
3 - BEARING HOUSING
4 - COMPRESSOR SECTION
5 - INLET AIR
6 - COMPRESSED AIR TO ENGINE
7 - EXHAUST GAS
8 - EXHAUST GAS TO EXHAUST PIPE
Fig. 2 Turbocharger Wastegate Actuator
1 - TURBOCHARGER
2 - DIAPHRAGM
3 - WASTE GATE ACTUATOR
11a - 2 EXHAUST SYSTEM AND TURBOCHARGERRG
The turbocharger is lubricated by engine oil that is
pressurized, cooled, and filtered. The oil is delivered
to the turbocharger by a supply line that is tapped
into the oil filter head. The oil travels into the bear-
ing housing, where it lubricates the shaft and bear-
ings (Fig. 4). A return pipe at the bottom of the
bearing housing, routes the engine oil back to the
crankcase.
The most common turbocharger failure is bearing
failure related to repeated hot shutdowns with inad-
equate ªcool-downº periods. A sudden engine shut
down after prolonged operation will result in the
transfer of heat from the turbine section of the tur-bocharger to the bearing housing. This causes the oil
to overheat and break down, which causes bearing
and shaft damage the next time the vehicle is
started.
Letting the engine idle after extended operation
allows the turbine housing to cool to normal operat-
ing temperature. The following chart should be used
as a guide in determining the amount of engine idle
time required to sufficiently cool down the turbo-
charger before shut down, depending upon the type
of driving and the amount of cargo.
TURBOCHARGER(COOL DOWN(CHART
Driving Load Turbocharger Idle Time (in
minutes)
Condition Temperature Before Shut
Down
Stop & Go Empty Cool Less than 1
Stop & Go Medium Warm 1
Highway
SpeedsMedium Warm 2
City Traffic Max.
GCWRWarm 3
Highway
SpeedsMax.
GCWRWarm 4
Uphill
GradeMax.
GCWRHot 5
Fig. 3 Wastegate Operation
1 - SIGNAL LINE
2 - EXHAUST BYPASS VALVE
3 - WASTE GATE
4 - EXHAUST
5 - TURBINE
6 - EXHAUST BYPASS VALVE
7 - WASTE GATE
8 - EXHAUST
9 - TURBINE
10 - SIGNAL LINE
Fig. 4 Turbocharger Oil Supply and Drain
1 - BEARINGS
2 - OIL SUPPLY (FROM ENGINE BLOCK)
3 - OIL RETURN (TO SUMP)
RGEXHAUST SYSTEM AND TURBOCHARGER11a-3
TURBOCHARGER SYSTEM (Continued)
TURBOCHARGER
REMOVAL
The exhaust manifold and turbocharger cannot be
remove with the engine in vehicle.
(1) Remove engine from vehicle and mount on
engine stand (Refer to 9 - ENGINE - REMOVAL) .
(2) Remove thermostat to upper radiator hose pipe
(Fig. 5).(3) Remove engine lift hook (Fig. 6).
(4) Remove exhaust manifold heat shield (Fig. 6).
(5) Disconnect turbocharger oil supply and return
lines at turbocharger (Fig. 6).
(6) Remove exhaust manifold retaining nuts (Fig.
6).
(7) Remove exhaust manifold and turbocharger
from engine (Fig. 6).
Fig. 5 TURBOCHARGER AND COOLANT PIPES
1 - TURBOCHARGER OUTLET PIPE RETAINING BOLT
2 - TURBOCHARGER OUTLET PIPE
3 - ADAPTER HOSE
4 - HEAT SHIELD
5 - HOSE CLAMPS
6 - TURBOCHARGER INLET PIPE RETAINING BOLT
7 - TURBOCHARGER INLET PIPE
8 - ADAPTER HOSE
9 - HOSE CLAMPS
10 - CLAMP
11 - EGR VALVE TO INTAKE AIR INLET PIPE
12 - CLAMP
13 - THERMOSTAT HOUSING TO UPPER RADIATOR HOSE
PIPE
Fig. 6 EXHAUST MANIFOLD AND TURBOCHARGER
1 - TURBOCHARGER OIL SUPPLY BANJO BOLT
2 - COPPER WASHER
3 - EXHAUST MANIFOLD GASKET
4 - COPPER WASHER
5 - EXHAUST MANIFOL HEAT SHIEL RETAINING BOLT
6 - TURBOCHARGER
7 - ENGINE LIFT HOOK
8 - ENGINE LIFT HOOK RETAINING BOLT
9 - SPACER
10 - EXHAUST MANIFOLD RETAINING NUT
11 - TURBOCHARGER OIL RETURN HOSE
12 - HOSE CLAMPS
13 - EXHAUST MANIFOLD STUDS
11a - 4 EXHAUST SYSTEM AND TURBOCHARGERRG