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Engine Exhaust System Buick LaCrosse I

Exhaust 1 illustration ~2839 words

Fastener Tightening Specifications

ApplicationSpecification
MetricEnglish
Catalytic Converter Bolt45 N.m33 lb ft
Catalytic Converter Nuts60 N.m44 lb ft
EGR Adapter Pipe to Exhaust Manifold Bolt 3.8L29 N.m21 lb ft
Engine Lift Bracket Bolt/Nut30 N.m22 lb ft
Exhaust Crossover Pipe Bolt/Nut 3.1L25 N.m18 lb ft
Exhaust Crossover Pipe Bolt/Stud 3.8L20 N.m15 lb ft
Exhaust Crossover Pipe Heat Shield Bolt 3.1L10 N.m89 lb in
Exhaust Crossover Pipe Heat Shield Nut20 N.m15 lb ft
Exhaust Manifold Bolt/Nut 3.8L30 N.m22 lb ft
Exhaust Manifold Heat Shield Bolt 3.1L10 N.m89 lb in
Exhaust Manifold Heat Shield Nuts 3.8L20 N.m15 lb ft
Exhaust Manifold Nut 3.1L16 N.m12 lb ft
Exhaust Manifold Pipe Stud Nut35 N.m26 lb ft
Exhaust Pipe Rear Hanger Bolt25 N.m18 lb ft
Fuel Injector Sight Shield Bracket Nut30 N.m22 lb ft
Rear Bumper Impact Bar Bolt25 N.m18 lb ft

Fastener Tightening Specifications

Diagnostic Starting Point - Engine Exhaust

Begin the system diagnosis by reviewing the system Description and Operation. Reviewing the information will help you determine the correct symptom diagnostic procedure when a malfunction exists. It will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Exhaust in order to identify the correct procedure for diagnosing the system.

Symptoms - Engine Exhaust

  1. Review the Exhaust System Description and Operation in order to familiarize yourself with the system functions. Refer to «Exhaust System Description»(/buick/lacrosse/i-2004-2009/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/i-2004-2009/remont/hoistjack/#general-information__strategy-based-diagnosis) in General Information.

Visual/Physical Inspection

  1. Inspect for aftermarket or non-OEM devices such as, but not including; tailpipe extensions, headers, and exhaust cutouts. This 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/i-2004-2009/remont/exhaust/#engine-exhaust-system) .
  2. Poor acceleration Refer to «Restricted Exhaust»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system) .
  3. Poor fuel economy Refer to «Restricted Exhaust»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system) .
  4. Excessive smoke-diesel Refer to «Restricted Exhaust»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system) .
  5. Exhaust hissing noise Refer to «Exhaust Leakage»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
  6. Exhaust popping noise Refer to «Exhaust Leakage»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
  7. Exhaust rattle noise Refer to «Exhaust Noise»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system__exhaust-noise) .
  8. Loud exhaust noise Refer to «Exhaust Noise»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system__exhaust-noise) .
  9. Exhaust buzz, groan, hum noise Refer to «Exhaust Noise»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system__exhaust-noise) .

Tools Required

J 35314-A Exhaust Back Pressure Gauge

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 the 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 J 35314-A Exhaust Back Pressure Gauge. See «Special Tools»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system__special-tools) . 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.
  4. 9: Confirming that the condition has been fixed is essential. If the symptom still exists, proceed to Step 2 and repeat the diagnostic procedure.
StepActionValue(s)YesNo
1Did you verify the customers complaint?Go to Step 2
2Did you review the exhaust symptoms diagnostic information and perform the necessary inspections?Go to Step 3Go to Symptoms - Engine Exhaust
3Is the system equipped with dual exhaust?Go to Diagnostic AidsGo to Step 4
4CAUTION: While engine is operating, the exhaust system will become extremely hot. To prevent burns avoid contacting a hot exhaust system. Remove the pre-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Position 1 in Engine Controls - 3.8L. Install the J 35314-A Exhaust Back Pressure Gauge in place of the HO2S sensor. See Special Tools . Start and run the engine. Increase and monitor the engine speed at 2500 RPM. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed the specified value?9 kPa (1.25 psi)Go to Step 5Go to Step 9
5Turn the engine off and place the ignition in the lock position. Remove the J 35314-A . See Special Tools . Install the pre-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Position 1 in Engine Controls - 3.8L. Remove the post-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Position 2 in Engine Controls - 3.8L. Install the J 35314-A in place of the post HO2S sensor. See Special Tools . Start and run the engine. Increase and monitor the engine speed at 2500 RPM. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed the specified value?9 kPa (1.25 psi)Go to Step 6Go to Step 7
6Inspect 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
7Replace the catalytic converter. Refer to Catalytic Converter Replacement . Did you find and correct the condition?Go to Step 8
8Remove the J 35314-A . See Special Tools . Install the post-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Position 2 in Engine Controls - 3.8L. Clear any codes. Road test the vehicle in order to verify the repair. Did you correct the condition?System OKGo to Step 2
9Remove the J 35314-A . See Special Tools . Install the pre-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Position 1 in Engine Controls - 3.8L. Clear any codes. Road test the vehicle in order to verify the repair. Did you correct the condition?System OKGo to Step 2
CAUTION
While engine is operating, the exhaust system will become extremely hot. To prevent burns avoid contacting a hot exhaust system.

Restricted Exhaust

Exhaust Leakage

ProblemAction
CAUTION: Refer to Hot Exhaust System Caution in Cautions and Notices. IMPORTANT: Refer to Symptoms - Engine Exhaust prior to beginning this table. 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.
Misaligned or improperly installed exhaust system componentsNOTE: Refer to Fastener Notice in Cautions and Notices. Align and tighten the components to the specifications. Refer to Fastener Tightening Specifications .
Exhaust leaks at the following connections: Exhaust manifold to pipe Flanges Pipe clampsTighten the components to the specifications. Refer to Fastener Tightening Specifications .
Seals or gaskets leaking: Exhaust manifold to cylinder head Exhaust pipes to exhaust manifold Catalytic converter connection EGR connections AIR connections to the exhaust manifold or cylinder headReplace the leaking seal or gasket. Refer to the affected components procedure for service.
Exhaust manifold cracked or brokenReplace the exhaust manifold. Refer to Exhaust Manifold Replacement - Left (LY7) or Exhaust Manifold Replacement - Right .
Exhaust system component connection welds leakingReplace the leaking component. Refer to the affected component's procedure for service.
Muffler is damaged or leaking at the seamsReplace the affected muffler. Refer to Muffler Replacement .
CAUTION
Refer to Hot Exhaust System Caution in Cautions and Notices.
IMPORTANT
Refer to Symptoms - Engine Exhaust prior to beginning this table.
NOTE
Refer to Fastener Notice in Cautions and Notices.

Exhaust Leakage

Exhaust Noise

ConditionAction
CAUTION: Refer to Hot Exhaust System Caution in Cautions and Notices. IMPORTANT: Refer to Symptoms - Engine Exhaust prior to beginning this table. 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.
Popping or hissing noiseExhaust leak. Refer to Exhaust Leakage .
Loud exhaustCompare to a known good vehicle. Inspect for a damaged or failed muffler. Replace the faulty muffler. Refer to Muffler Replacement .
External rattle or vibration noiseInspect for a bent or loose hanger, loose heat shield, or loose clamp. Inspect for a exhaust pipe causing interference. Repair or replace the affected component. Refer to the affected component's service procedure.
Internal rattleTest the components by tapping with a rubber mallet to confirm a rattle. Replace the faulty catalytic converter, resonator, or muffler. Refer to one of the following procedures: Catalytic Converter Replacement Muffler Replacement
CAUTION
Refer to Hot Exhaust System Caution in Cautions and Notices.
IMPORTANT
Refer to Symptoms - Engine Exhaust prior to beginning this table.

Exhaust Noise

Removal Procedure

  1. Turn the ignition OFF.
  2. Remove the left and the right torque strut bolts at the engine strut bracket.
  3. Remove the exhaust crossover pipe to left bank exhaust manifold nuts (5).
  4. Remove the oil lever indicator and tube. Refer to «Oil Level Indicator and Tube Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-36l-ly7-repair-instructions-1-of-5) .
  5. Remove the exhaust manifold heat shield bolts.
  6. Remove the exhaust manifold heat shield.
  7. Remove the exhaust manifold bolts.
  8. Remove the exhaust manifold.
  9. Remove and discard the exhaust manifold gasket.
  10. Clean and inspect the exhaust manifold and the sealing surfaces. Refer to «Exhaust Manifold Cleaning and Inspection - Left»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-36l-ly7-repair-instructions-3-of-5) in Engine Mechanical - 3.6L (LY7).

Installation Procedure

  1. Install the NEW exhaust manifold gasket.
  2. Install the exhaust manifold.
  3. Install the exhaust manifold bolts. Tighten: Tighten the bolts to 20 N.m (15 lb ft).
  4. Install the exhaust manifold heat shield.
  5. Install the exhaust manifold heat shield bolts. Tighten: Tighten the bolts to 10 N.m (89 lb in).
  6. Install the oil lever indicator and tube. Refer to «Oil Level Indicator and Tube Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-36l-ly7-repair-instructions-1-of-5) .
  7. Install the exhaust crossover pipe to left bank exhaust manifold nuts (5). Refer to «Exhaust Crossover Pipe Replacement»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system) .
  8. Install the left and the right torque strut at the engine. Secure with the strut bolts. Tighten: Tighten the bolts to 48 N.m (35 lb ft).
  1. Remove the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
  2. Remove the exhaust crossover heat shield nuts (1).
  3. Remove the exhaust crossover heat shield (2).
  4. Remove the exhaust crossover pipe studs (3) from the right exhaust manifold.
  5. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  6. Remove the exhaust manifold pipe stud nuts (2) and the catalytic converter pipe (3) from the right exhaust manifold.
  7. Lower the vehicle.
  8. Rotate the engine to access the right side of the engine. Refer to «Rotating the Engine for Service Access»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
  9. Disconnect the heated oxygen sensor (HO2S) electrical connector (1).
  10. Remove the HO2S electrical connector (1) from the engine sight shield bracket.
  11. Remove the HO2S (2) from the right exhaust manifold. Refer to «Heated Oxygen Sensor Replacement - Position 1»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2)
  12. Remove the right side spark plugs from cylinders 2, 4 and 6. Refer to «Spark Plug Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L.
  13. Remove the fuel injector sight shield bracket nuts (2).
  14. Remove the fuel injector sight shield bracket (1).
  15. Remove the right engine lift bracket bolt (2) and the nut (3).
  16. Remove the right engine lift bracket (1).
  17. Remove the right exhaust manifold heat shield bolts (2).
  18. Remove the right exhaust manifold heat shield (1).
  19. Raise the vehicle.
  20. Remove the exhaust gas recirculation (EGR) valve inlet adapter pipe bolt (1) from the right exhaust manifold.
  21. Lower the vehicle.
  22. Remove the right exhaust manifold studs (4) and the nuts (3).
  23. Remove the right exhaust manifold (2).
  24. Remove the right exhaust manifold gasket (1).
  25. Remove the exhaust manifold studs if damaged.
  26. Clean and Inspect the right exhaust manifold. Refer to «Exhaust Manifold Cleaning and Inspection»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l__exhaust-manifold-cleaning-inspection) in Engine Mechanical - 3.8L.
  1. Install the exhaust manifold studs if removed.
  2. Install the right exhaust manifold gasket (1).
  3. Install the right exhaust manifold (2).
  4. Install the right exhaust manifold studs (4) and the nuts (3). Tighten: Tighten the studs and the nuts to 30 N.m (22 lb ft).
  5. Raise the vehicle.
  6. Install the exhaust gas recirculation (EGR) valve inlet adapter pipe bolt (1) to the right exhaust manifold. Tighten: Tighten the bolt to 29 N.m (21 lb ft).
  7. Lower the vehicle.
  8. Install the right exhaust manifold heat shield (1).
  9. Install the right exhaust manifold heat shield bolts (2). Tighten: Tighten the bolts to 10 N.m (89 lb in).
  10. Install the right engine lift bracket (1).
  11. Install the right engine lift bracket bolt (2) and the nut (3). Tighten: Tighten the bolt and the nut to 30 N.m (22 lb ft).
  12. Install the fuel injector sight shield bracket (1).
  13. Install the fuel injector sight shield bracket nuts (2). Tighten: Tighten the nuts to 30 N.m (22 lb ft).
  14. Install the right side spark plugs to cylinders 2, 4 and 6. Refer to «Spark Plug Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L.
  15. Install the HO2S (2) to the right exhaust manifold. Refer to «Heated Oxygen Sensor Replacement - Position 1»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2)
  16. Install the HO2S electrical connector (1) to the engine sight shield bracket.
  17. Connect the HO2S electrical connector (1).
  18. Return the engine to the original position.
  19. Raise the vehicle.
  20. Install the catalytic converter pipe (3) to the right exhaust manifold.
  21. Install the catalytic converter pipe stud nuts (2) to the right exhaust manifold. Tighten: Tighten the stud nuts to 35 N.m (26 lb ft).
  22. Lower the vehicle.
  23. Install the exhaust crossover pipe studs (3) to the right exhaust manifold. Tighten: Tighten the studs to 20 N.m (15 lb ft).
  24. Install the exhaust crossover heat shield (2).
  25. Install the exhaust crossover heat shield nuts (1). Tighten: Tighten the nuts to 20 N.m (15 lb ft).
  26. Install the engine mount struts. Refer to «Engine Mount Strut Replacement - Right»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) and «Engine Mount Strut Replacement - Left»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
  27. Install the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
  1. Remove the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
  2. Remove the air cleaner intake duct. Refer to «Air Cleaner Intake Duct Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L.
  3. Remove the exhaust crossover heat shield nuts (1).
  4. Remove the exhaust crossover heat shield (2).
  5. Remove the exhaust crossover pipe studs (3) and the bolts (2).
  6. Remove the exhaust crossover pipe (1).
  7. Remove the exhaust crossover pipe seal (4).
  1. Install the exhaust crossover pipe seal (4) to the exhaust crossover pipe (1) at the right exhaust manifold connection.
  2. Install the exhaust crossover pipe (1).
  3. Install the exhaust crossover pipe studs (3) and the bolts (2). Tighten: Tighten the studs and the bolts to 20 N.m (15 lb ft).
  4. Install the exhaust crossover heat shield (2).
  5. Install the exhaust crossover heat shield nuts (1). Tighten: Tighten the nuts to 25 N.m (18 lb ft).
  6. Install the air cleaner intake duct. Refer to «Air Cleaner Intake Duct Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L.
  7. Install the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  2. Remove the exhaust manifold nuts from the exhaust manifold pipe studs.
  3. Remove the catalytic converter exhaust hangers.
  4. Reposition the exhaust system.
  5. Remove the exhaust manifold pipe gasket.
  1. Install the exhaust manifold pipe gasket.
  2. Install the exhaust system to the original position
  3. Install the catalytic converter exhaust hangers.
  4. Remove the support from the exhaust system.
  5. Install the exhaust manifold pipe nuts to the exhaust manifold pipe studs. Tighten: Tighten the nuts to 35 N.m (26 lb ft).
  6. Inspect the exhaust system for leaks and underbody contact.
  7. Lower the vehicle.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  2. Disconnect the heated oxygen sensor (HO2S) electrical connector.
  3. Remove the exhaust manifold pipe stud nuts (2).
  4. Remove the exhaust manifold pipe gasket (1).
  5. Support the exhaust system.
  6. Remove the catalytic converter nuts.
  7. Remove the catalytic converter hangers.
  8. Remove the catalytic converter.
  9. Remove the catalytic converter gasket.
  10. Clean and inspect the exhaust manifold and the exhaust pipe gasket mating surfaces.
  11. Remove the HO2S. Refer to «Heated Oxygen Sensor Replacement - Position 2»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L.
  1. Install the HO2S. Refer to «Heated Oxygen Sensor Replacement - Position 2»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L.
  2. Install a new gasket to the exhaust pipe studs.
  3. Install and support the catalytic converter.
  4. Install the catalytic converter nuts. Tighten: Tighten the nuts to 60 N.m (44 lb ft).
  5. Install a new exhaust manifold pipe gasket (1).
  6. Install the exhaust manifold pipe stud nuts (2). Tighten: Tighten the nuts to 35 N.m (26 lb ft).
  7. Install the catalytic converter hangers.
  8. Remove the support from the exhaust system.
  9. Connect the HO2S electrical connector.
  10. Inspect the exhaust system for leaks and underbody contact.
  11. Lower the vehicle.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  2. Support the exhaust system.
  3. Remove the exhaust pipe hanger (3) from the exhaust pipe (2) and the exhaust hanger bracket (1).
  4. Remove the exhaust pipe hanger from the exhaust pipe and the exhaust hanger bracket.
  5. Remove the exhaust pipe rear hangers from the muffler and the rear exhaust hanger brackets.
  1. Install the exhaust pipe rear hangers to the muffler and the rear exhaust hanger brackets.
  2. Install the exhaust pipe hanger to the exhaust pipe and the exhaust hanger bracket.
  3. Install the exhaust pipe hanger (3) to the exhaust pipe (2) and the exhaust hanger bracket (1).
  4. Remove the support from the exhaust system.
  5. Inspect the exhaust system for underbody contact.
  6. Lower the vehicle.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  2. Support the exhaust system.
  3. Remove the exhaust pipe rear hanger insulators from the exhaust muffler rear hanger bracket.
  4. Loosen the outboard rear bumper impact bar bolt.
  5. Remove the inboard rear bumper impact bar bolt.
  6. Remove the exhaust muffler rear hanger bracket.
  1. Install the exhaust muffler rear hanger bracket.
  2. Install the inboard and the outboard rear bumper impact bar bolts. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
  3. Install the exhaust pipe rear hanger insulators to the exhaust muffler rear hanger bracket.
  4. Remove the support from the exhaust system.
  5. Inspect the exhaust system for underbody contact.
  6. Lower the vehicle.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  2. Support the exhaust system.
  3. Remove the catalytic converter bolts.
  4. Remove the catalytic converter gasket.
  5. Remove the exhaust hanger insulators from the muffler.
  6. Remove the muffler from the support.
  1. Install the muffler to the support.
  2. Install the exhaust hanger insulators to the muffler.
  3. Install the catalytic converter gasket.
  4. Install the catalytic converter bolts. Tighten: Tighten the bolts to 45 N.m (33 lb ft).
  5. Remove the support from the exhaust system.
  6. Inspect the exhaust system for leaks and underbody contact.
  7. Lower the vehicle.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  2. Support the exhaust system.
  3. Remove the 3-way catalytic converter pipe hangers.
  4. Inspect the 3-way catalytic converter brackets for serviceability. Repair or replace as necessary.
  1. Install the 3-way catalytic converter pipe hangers.
  2. Remove the support from the exhaust system and the vehicle.
  3. Inspect the exhaust system for underbody contact.
  4. Lower the vehicle.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
  2. Support the exhaust system.
  3. Remove the catalytic converter. Refer to «Catalytic Converter Replacement»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system) .
  4. Remove the oxygen sensor wiring harness (3) from the catalytic converter heat shield.
  5. Remove the catalytic converter heat shield rivets.
  6. Remove the catalytic converter heat shield.
  1. Install the catalytic converter heat shield.
  2. Install the converter heat shield rivets.
  3. Install the oxygen sensor wiring harness (3) to the catalytic converter heat shield.
  4. Install the catalytic converter. Refer to «Catalytic Converter Replacement»(/buick/lacrosse/i-2004-2009/remont/exhaust/#engine-exhaust-system) .
  5. Remove the support from the exhaust system.
  6. Inspect the exhaust system for leaks and underbody contact.
  7. Lower the vehicle.

Exhaust System Description

IMPORTANTUse 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 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

  1. Platinum (Pt)
  2. Palladium (Pd)
  3. 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

Special Tools Illustration Tool Number/Description J 35314-A Exhaust Back Pressure Gauge

Scheme 1

Scheme 1: Special Tools
Scheme 1: Special Tools