Engine Exhaust System Buick LaCrosse II

Fastener Tightening Specifications

Fastener Tightening Specifications

Adhesives, Fluids, Lubricants, and Sealers

Adhesives, Fluids, Lubricants, and Sealers

Symptoms - Engine Exhaust

1. Review the exhaust system description in order to familiarize yourself with the exhaust system components and the intended function of the components. Refer to «Exhaust System Description»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-system-description) .
2. All diagnostics on a vehicle should follow a logical process. Strategy Based Diagnostics is a uniform approach for repairing all systems. The diagnostic flow is the place to start when repairs are necessary and may always be used in order to resolve a system problem. For a detailed explanation, refer to «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) .

Visual/Physical Inspection

1. Inspect for aftermarket or non-OEM devices such as, but not limited to; tailpipe extensions, headers, and exhaust cutouts. Any aftermarket exhaust system devices could affect the operation and proper performance of the exhaust system.
2. Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, engine temperature, engine load, and frequency of concern.
3. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause any symptom.

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system is operating as designed.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. Loss of power - Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) .
2. Poor acceleration - Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) .
3. Poor fuel economy - Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) .
4. Excessive smoke diesel - Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) .
5. Exhaust hissing noise - Refer to «Exhaust Leakage»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
6. Exhaust popping noise - Refer to «Exhaust Leakage»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
7. Exhaust rattle noise - Refer to «Exhaust Noise»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-noise) .
8. Loud exhaust noise - Refer to «Exhaust Noise»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-noise) .
9. Exhaust buzz, groan, hum noise - Refer to «Exhaust Noise»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-noise) .

Restricted Exhaust

Special Tools

EN-35314 Exhaust Pressure Gauge

For equivalent regional special tools, refer to Special Tools .

Diagnostic Aids

For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and diagnosis should begin there.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 4 The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the EN-35314 gauge. Removing the HO2S sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes.
2. 5 This step will isolate the catalytic converter from the remainder of the exhaust system.
3. 8 Confirming that the condition has been fixed is essential. If the symptom still exists and the vehicle has a dual exhaust system, proceed to step 2 and repeat diagnostic procedure on the opposite exhaust pipe.

Restricted Exhaust

Exhaust Leakage

Exhaust Leakage

Exhaust Noise

Exhaust Noise

Scheme 1

Exhaust Manifold Replacement (LUK)

Removal Procedure

1. Remove the front pipe exhaust fasteners (1) from the rear muffler pipe and discard the exhaust gasket (2).
2. Support the exhaust muffler with a suitable wire hanger.
3. Remove the fasteners (1) from the right catalytic converter and discard the gasket (2).
4. Remove the fasteners (1) from the left catalytic converter and discard the gasket (3).
5. If equipped with AWD, remove the fastener (1) from the hanger rod.
6. Slide out the exhaust front pipe (2) from the exhaust isolator (3) and lower to the floor.
7. If equipped with FWD, remove the exhaust front hanger bracket nuts (1).
8. Remove the exhaust isolator studs, from the hanger bracket, and slide the front pipe (1) out from the hanger bracket.

Installation Procedure

1. If equipped with FWD, install the exhaust front pipe (1) into the opening on the hanger bracket.
2. Install the fasteners (1) to the exhaust isolators and tighten to 22 N.m (16 lb ft).
3. If equipped with AWD, install the exhaust isolator rod into position and tighten the fastener (1) to 35 N.m (26 lb ft).
4. Install the exhaust front pipe fasteners (1) to the rear muffler with a NEW gasket (2), and tighten to 18 N.m (13 lb ft).
5. Install the exhaust front pipe fasteners (1) to the right catalytic converter, with a NEW gasket (2), and tighten to 50 N.m (37 lb ft).
6. Install the exhaust front pipe fasteners (1) to the left catalytic converter (2), with a NEW gasket (3) and tighten to 50 N.m (37 lb ft).
7. Inspect the exhaust system for leaks.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Disconnect the oxygen sensors after the catalytic converter.
3. Remove the front exhaust nuts (1) from the rear muffler pipe.
4. Remove the nuts (1) and gasket (2) from the lower catalytic converter.
5. Remove the bolts (1) from the front exhaust pipe hanger bracket (2).
6. Carefully lower the front exhaust pipe (3).

1. Install the front exhaust pipe nuts (2) and NEW gasket (1), to the rear muffler pipe and tighten to 18 N.m (13 lb ft).
2. Install the nuts (1) of the front exhaust pipe to the lower catalytic converter and tighten to 28 N.m (21 lb ft).
3. Install the bolts (1) to the front exhaust pipe hanger bracket (2) and tighten to 60 N.m (44 lb ft).
4. Connect the oxygen sensor electrical sensors.
5. Inspect the exhaust system for leaks.

Scheme 2

Catalytic Converter Replacement (LUK)

Scheme 3

Catalytic Converter Replacement - Left Side (LFX-Front)

Scheme 4

Catalytic Converter Replacement - Right Side (LFX-Rear)

Scheme 5

Exhaust Muffler Replacement (Single)

1. Remove the exhaust front pipe fasteners (2) securing the rear muffler assembly (4) and discard the exhaust gasket (3).
2. Support the exhaust muffler with a suitable wire hanger.
3. With the help of a second technician, remove the exhaust muffler (3) from the rear exhaust hanger isolators (1) and (2).
4. Lower the exhaust muffler (3) to the floor.

1. With the help of a technician, install the exhaust muffler (3) into the rear exhaust hanger isolators (1) and (2).
2. Install the rear muffler (4) to the exhaust front pipe with a NEW gasket (3) and tighten the fasteners (2) to 18 N.m (13 lb ft).
3. Inspect the exhaust system for leaks.

Scheme 6

Exhaust Muffler Center Heat Shield Replacement

Scheme 7

Exhaust Manifold Heat Shield Replacement (LUK)

Scheme 8

Exhaust Rear Muffler Heat Shield Replacement (Left Outer-LUK)

Scheme 9

Exhaust Rear Muffler Heat Shield Replacement (Left Inner-LUK)

Exhaust System Description

Note. Use of non-OEM parts may cause driveability concerns.

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

1. Exhaust manifold
2. Exhaust pipes
3. Catalytic converters
4. Exhaust muffler
5. Exhaust resonator, if equipped
6. Exhaust tail pipe, if equipped
7. Exhaust hangers
8. 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

The catalytic converter is an emission control device used 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

1. Platium (Pt)
2. Palladium (Pd)
3. Rhodium (Rh)

The catalyst in the catalytic 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

Illustration Tool Number/Description EN-35314-A J-35314-A Exhaust Back Pressure Gauge CH-6179 KM-6179 Heated Oxygen Sensor Remover/Installer CH-6614 MKM-6614 83 95 667 Chain-type Pipe Cutter

Scheme 10

See also:
• Strategy Based Diagnosis
• Hot Exhaust System Warning
• Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (LFW or LFX)
• Heated Oxygen Sensor Replacement - Sensor 1
• Fastener Caution
• Safety Glasses Warning
• Lifting and Jacking the Vehicle
• Eye Protection Warning
• Intake Manifold Cover Replacement
• Exhaust System Description
• Restricted Exhaust
• Exhaust Leakage
• Exhaust Noise
• Special Tools
• Symptoms - Engine Exhaust
• Catalytic Converter Replacement - Left Side (LFX-Front)
• Fastener Tightening Specifications