Engine Exhaust System Cadillac STS I

Fastener Tightening Specifications

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»(/cadillac/sts/i-2004-2007/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»(/cadillac/sts/i-2004-2007/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»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
2. Poor acceleration Refer to «Restricted Exhaust»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
3. Poor fuel economy Refer to «Restricted Exhaust»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
4. Excessive smoke-diesel Refer to «Restricted Exhaust»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
5. Exhaust hissing noise Refer to «Exhaust Leakage»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
6. Exhaust popping noise Refer to «Exhaust Leakage»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
7. Exhaust rattle noise Refer to «Exhaust Noise»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system__exhaust-noise) .
8. Loud exhaust noise Refer to «Exhaust Noise»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system__exhaust-noise) .
9. Exhaust buzz, groan, hum noise Refer to «Exhaust Noise»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system__exhaust-noise) .

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 J 35314-A . See «Special Tools»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system__special-tools) . Removing the heated oxygen (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

Removal Procedure

1. Remove the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Left (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Left (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
2. Remove the oil level indicator. Refer to «Oil Level Indicator and Tube Replacement»(/cadillac/sts/i-2004-2007/remont/mechanical/#engine-mechanical-36l-ly7-2-of-6) in Engine Mechanical - 3.6L (LY7).
3. Remove the catalytic converter nuts.
4. Remove the exhaust manifold bolts.
5. Remove the exhaust manifold and discard the exhaust manifold gasket.
6. Clean and inspect the exhaust manifold. Refer to «Exhaust Manifold Cleaning and Inspection - Left»(/cadillac/sts/i-2004-2007/remont/mechanical/#engine-mechanical-36l-ly7-5-of-6) in Engine Mechanical - 3.6L.

Installation Procedure

1. Install the catalytic converter seal/heat shield to the catalytic converter.
2. Install a NEW exhaust manifold gasket to the exhaust manifold.
3. Install the exhaust manifold with the gasket to the catalytic converter and the cylinder head.
4. Install the exhaust manifold bolts. Tighten: Tighten the exhaust manifold bolts to 20 N.m (15 lb ft).
5. Install the catalytic converter nuts. Tighten: Tighten the catalytic converter nuts to 50 N.m (37 lb ft).
6. Install the oil level indicator. Refer to «Oil Level Indicator and Tube Replacement»(/cadillac/sts/i-2004-2007/remont/mechanical/#engine-mechanical-36l-ly7-2-of-6) in Engine Mechanical - 3.6L (LY7).
7. Install the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Left (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Left (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .

1. Disconnect the heated oxygen sensor pigtail from the wiring harness connector.
2. Remove the left exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Left (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Left (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
3. Remove the heated oxygen sensor, if necessary. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) in Engine Controls - 4.6L.
4. Remove the left exhaust manifold bolts and nuts. Discard the exhaust manifold bolts.
5. Remove the exhaust manifold studs, if necessary.
6. Remove the left exhaust manifold and gasket from the engine. Do not reuse the gasket.
7. Clean and inspect the left exhaust manifold. Refer to «Exhaust Manifold Cleaning and Inspection - Left»(/cadillac/sts/i-2004-2007/remont/mechanical/#engine-mechanical-46l-lh2-5-of-6) in Engine Mechanical - 4.6L (LH2).

1. Use a NEW exhaust manifold gasket.
2. Position the left exhaust manifold and gasket to the left cylinder head.
3. Install the left exhaust manifold studs, nuts and NEW bolts. Tighten: Tighten the exhaust manifold studs to 6 N.m (53 lb in). Tighten the exhaust manifold nuts to 25 N.m (18 lb ft). Tighten the exhaust manifold bolts to 25 N.m (18 lb ft).
4. Install the heated oxygen sensor if previously removed. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) in Engine Controls - 4.6L (LH2).
5. Install the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Left (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Left (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
6. Connect the heated oxygen sensor pigtail to the wiring harness connector.

1. Remove the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Right (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Right (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
2. Remove the catalytic converter nuts.
3. Remove the exhaust manifold bolts.
4. Remove the exhaust manifold and discard the exhaust manifold gasket.
5. Clean and inspect the exhaust manifold. Refer to «Exhaust Manifold Cleaning and Inspection - Left»(/cadillac/sts/i-2004-2007/remont/mechanical/#engine-mechanical-36l-ly7-5-of-6) in Engine Mechanical - 3.6L.

1. Install the catalytic converter seal/heat shield to the catalytic converter.
2. Install a NEW exhaust manifold gasket to the exhaust manifold.
3. Install the exhaust manifold with the gasket to the catalytic converter and the cylinder head.
4. Install the exhaust manifold bolts. Tighten: Tighten the exhaust manifold bolts to 20 N.m (15 lb ft).
5. Install the catalytic converter nuts. Tighten: Tighten the catalytic converter nuts to 50 N.m (37 lb ft).
6. Install the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Right (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Right (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .

1. Disconnect the heated oxygen sensor pigtail from the wiring harness connector.
2. Remove the right exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Right (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Right (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
3. Remove the heated oxygen sensor, if necessary. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) in Engine Controls - 4.6L.
4. Remove the right exhaust manifold bolts and nuts. Discard the exhaust manifold bolts.
5. Remove the exhaust manifold studs, if necessary.
6. Remove the right exhaust manifold and gasket from the engine. Do not reuse the gasket.
7. Clean and inspect the right exhaust manifold. Refer to «Exhaust Manifold Cleaning and Inspection - Right»(/cadillac/sts/i-2004-2007/remont/mechanical/#engine-mechanical-46l-lh2-5-of-6) in Engine Mechanical - 4.6L (LH2).

1. Use a NEW exhaust manifold gasket over the cylinder head studs.
2. Position the right exhaust manifold and gasket to the right cylinder head.
3. Install the right exhaust manifold studs, nuts and NEW bolts. Tighten: Tighten the exhaust manifold studs to 6 N.m (53 lb in). Tighten the exhaust manifold nuts to 25 N.m (18 lb ft). Tighten the exhaust manifold bolts to 25 N.m (18 lb ft).
4. Install the heated oxygen sensor if previously removed. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) in Engine Controls - 4.6L (LH2).
5. Install the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Right (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Right (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
6. Connect the heated oxygen sensor pigtail to the wiring harness connector.

Exhaust System Replacement

Servicing of the muffler, resonator or pipe requires the replacement of the exhaust system as a complete one-piece unit.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Remove the heated oxygen sensors from the exhaust pipes. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) and «Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 2»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) in Engine Controls - 4.6L.
3. Remove the 2 bolts securing the floor panel tunnel brace to the floor panel.
4. Remove the floor panel tunnel brace from the floor panel.
5. Suitably support the exhaust system.
6. Remove the nuts securing the exhaust pipes to the exhaust manifolds.
7. Pry the front exhaust hangers (1) free from the rear suspension hanger rods.
8. Apply a suitable lubricant to the tail pipe hanger rods in order to ease the removal of the tail pipe hangers (1).
9. Pry the tail pipe hangers (1) free from the tail pipe hanger rods.
10. With the aid of an assistant, lower the exhaust system.
11. Remove the exhaust manifold seals. Do not reuse the seals.
12. While the exhaust system is on the floor complete the following: Apply a suitable lubricant to the exhaust pipe hanger rods (3) in order to ease the removal of the front exhaust hangers (2). Pull the front exhaust hangers (2) from the exhaust pipe hanger rods.

1. While the exhaust system is on the floor complete the following: Apply a soapy solution to the following in order to ease the installation of the hangers: The inner diameter of the front exhaust hangers The exhaust pipe hanger rods The inner diameter of the tail pipe hangers The tail pipe hanger rods Press the front exhaust hangers over the exhaust pipe hanger rods.
2. Place NEW seals on the exhaust manifold flanges.
3. With the aid of an assistant, raise the exhaust system into position, aligning the exhaust pipe flanges with the studs located in the rear of the exhaust manifolds.
4. Finger tighten the nuts to the exhaust manifold studs.
5. Press the tail pipe hangers (1) over the tail pipe hanger rods.
6. Press the front exhaust hangers (1) over the rear suspension hanger rods.
7. Tighten the exhaust pipes to exhaust manifold nuts. Tighten: Tighten the exhaust manifold nuts to 30 N.m (22 lb ft).
8. Position the floor panel tunnel brace to the floor panel.
9. Install the 2 bolts securing the floor panel tunnel brace to the floor panel. Tighten: Tighten the floor panel tunnel brace bolts to 25 N.m (18 lb ft).
10. Install the heated oxygen sensors to the exhaust pipes. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) and «Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 2»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-46l-lh2-introduction) in Engine Controls - 4.6L.
11. Lower the vehicle.

1. Remove the left bank exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Left (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Left (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
2. Remove the catalytic converter nuts.
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
4. Disconnect the oxygen sensor electrical connector.
5. Disconnect the muffler pipe from the left and right side catalytic converters.
6. Remove the exhaust pipe to right bank catalytic converter fasteners.
7. Carefully remove the catalytic converter with the seal/heat shield and oxygen sensor from the exhaust manifold.
8. Remove the oxygen sensor from the catalytic converter. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction) in Engine Controls - 3.6L (LY7).

1. Install the oxygen sensor to the catalytic converter. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction) in Engine Controls - 3.6L (LY7).
2. Install the catalytic converter seal/heat shield to the catalytic converter.
3. Carefully install the catalytic converter to the exhaust manifold.
4. Install the catalytic converter nuts.
5. Connect the oxygen sensor electrical connector.
6. Connect the muffler pipes to the left and right side catalytic converters. Tighten: Tighten the muffler nuts to 22 N.m (16 lb ft).
7. Lower the vehicle.
8. Tighten the catalytic converter to exhaust manifold fasteners. Tighten: Tighten the catalytic converter nuts to 50 N.m (37 lb ft).
9. Install the right bank exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Left (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Left (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .

1. Remove the right bank exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Right (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Right (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .
2. Remove the catalytic converter nuts.
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
4. If equipped with AWD, remove the front driveshaft. Refer to «Propeller Shaft Replacement - Front»(/cadillac/sts/i-2004-2007/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) in Propeller Shaft.
5. Disconnect the oxygen sensor electrical connector.
6. Disconnect the muffler pipe from the left and right side catalytic converters.
7. Remove the exhaust pipe to right bank catalytic converter fasteners.
8. Carefully remove the catalytic converter with the seal/heat shield and oxygen sensor from the exhaust manifold.
9. Remove the oxygen sensor from the catalytic converter. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction) in Engine Controls - 3.6L (LY7).

1. Install the oxygen sensor to the catalytic converter. Refer to «Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1»(/cadillac/sts/i-2004-2007/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction) in Engine Controls - 3.6L (LY7).
2. Install the catalytic converter seal/heat shield to the catalytic converter.
3. Carefully install the catalytic converter to the exhaust manifold.
4. Install the catalytic converter to exhaust manifold fasteners.
5. Connect the oxygen sensor electrical connector.
6. Connect the muffler pipes to the left and right side catalytic converters. Tighten: Tighten the muffler nuts to 22 N.m (16 lb ft).
7. If equipped with AWD, install the front driveshaft. Refer to «Propeller Shaft Replacement - Front»(/cadillac/sts/i-2004-2007/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) in Propeller Shaft.
8. Lower the vehicle.
9. Tighten the catalytic converter nuts. Tighten: Tighten the catalytic converter nuts to 50 N.m (37 lb ft).
10. Install the right bank exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement - Right (LY7)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) or «Exhaust Manifold Heat Shield Replacement - Right (LH2)»(/cadillac/sts/i-2004-2007/remont/exhaust/#engine-exhaust-system) .

Exhaust Hanger Replacement

Service the exhaust hangers individually in order to retain the support of the exhaust system.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Pry the front exhaust hanger (1) free from the rear suspension hanger rod (2).
3. Apply a suitable lubricant to the exhaust pipe hanger rod (3) in order to ease the removal of the hanger (1).
4. Pry the front exhaust hanger (1) free from the exhaust pipe hanger rod (3).
5. Apply a suitable lubricant to the following in order to ease the removal of the hanger (2): The body support bracket rod (1) The tail pipe hanger rod (3)
6. Pry the tail pipe hanger (2) free from the tail pipe hanger rod (3).
7. Pry the tail pipe hanger (2) free from the body support bracket rod (1).

1. Apply a soapy solution to the following in order to ease the installation of the hanger: The body support bracket rod (1) The inner diameter of the tail pipe hanger (2) The tail pipe hanger rod (3)
2. Press the tail pipe hanger (2) over the tail pipe hanger rod (3).
3. Press the tail pipe hanger (2) over the body support bracket rod (1).
4. Apply a soapy solution to the exhaust pipe hanger rod (3) and the inner diameter of the front exhaust hanger (1) in order to ease the installation of the hanger (1).
5. Press the front exhaust hanger (1) over the exhaust pipe hanger rod (3).
6. Press the front exhaust hanger (1) over the rear suspension hanger rod (2).
7. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Apply a suitable lubricant to the following in order to ease the removal of the hangers (2): The left exhaust hanger mounting bracket rod (1) The tail pipe hanger rods (3)
3. Pry the tail pipe hangers (2) free from the tail pipe hanger rods (3).
4. Pry the tail pipe hangers (2) free from the exhaust hanger mounting bracket rods (1).
5. Remove the nuts securing the rear energy absorber and the exhaust hanger mounting bracket (2) to the rear compartment rail.
6. Remove the stud plate (1) from the rear energy absorber.
7. Remove the exhaust hanger mounting bracket from the rear energy absorber.

1. Position the exhaust hanger mounting bracket (2) between the rear energy absorber and the stud plate (1). Insert the stud plate (1) through the exhaust hanger mounting bracket (2), the rear energy absorber and the rear compartment rail.
2. Install the nuts securing the rear energy absorber and the exhaust hanger mounting bracket (2) to the rear compartment rail. Tighten: Tighten the bumper nuts to 25 N.m (18 lb ft).
3. Apply a soapy solution to the following in order to ease the installation of the hangers: The left exhaust hanger mounting bracket rod (1) The inner diameter of the tail pipe hangers (2) The tail pipe hanger rods (3)
4. Press the tail pipe hangers (2) over the tail pipe hanger rods (3).
5. Press the tail pipe hangers (2) over the exhaust hanger mounting bracket rods (1).
6. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) .
2. Remove the exhaust system from the rear suspension hanger rods, and the tail pipe hanger rods.
3. Mark the location of the existing exhaust tip on the exhaust pipe.
4. Remove the weld from the top and bottom of the exhaust tip.
5. Remove the exhaust tip.
6. Clean the remaining weld from the exhaust pipe.

1. Install the NEW exhaust tip to the exhaust pipe, and align to the mark previously made during disassembly.
2. Re-install the exhaust system to the rear suspension hanger rods, and the tail pipe hanger rods.
3. Visually align the exhaust tip to the vehicle.
4. Tack weld the exhaust tip to the vehicle.
5. Remove the exhaust system from the rear suspension hanger rods, and the tail pipe hanger rods.
6. Weld the exhaust tip to the exhaust pipe in the same locations the original tip had been welded.
7. Re-install the exhaust system to the rear suspension hanger rods, and the tail pipe hanger rods.

1. Remove the exhaust manifold heat shield bolts.
2. Remove the exhaust manifold heat shield.
3. Remove the lower exhaust manifold heat shield retainers (1), if necessary.
4. Remove the lower exhaust manifold heat shield (2), if necessary.

1. Install the lower exhaust manifold heat shield (2), if necessary.
2. Install the lower exhaust manifold heat shield retainers (1), if necessary.
3. Install the exhaust manifold heat shield.
4. Install the exhaust manifold heat shield bolts. Tighten: Tighten the bolts to 10 N.m (89 lb in).

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Remove the bolts securing the exhaust manifold heat shield to the exhaust manifold.
3. Remove the heat shield from the engine.

1. Install the exhaust manifold heat shield to the engine.
2. Install the bolts securing the exhaust manifold heat shield to the manifold. Tighten: Tighten the bolts to 10 N.m (89 lb in).
3. Lower the vehicle.

1. Remove the exhaust manifold heat shield bolts.
2. Remove the exhaust manifold heat shield.
3. Remove the upper exhaust manifold heat shield insulator from the oil level indicator tube, if necessary.
4. Remove the lower exhaust manifold heat shield insulator from the oil level indicator and exhaust gasket, if necessary.

1. Install the lower exhaust manifold heat shield insulator to the oil level indicator and exhaust gasket, if necessary.
2. Install the upper exhaust manifold heat shield insulator to the oil level indicator tube, if necessary.
3. Install the exhaust manifold heat shield.
4. Install the exhaust manifold heat shield bolts. Tighten: Tighten the bolts to 10 N.m (89 lb in).

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Remove the bolts securing the exhaust manifold heat shield to the exhaust manifold.
3. Remove the heat shield from the engine.

1. Install the exhaust manifold heat shield to the engine.
2. Install the bolts securing the exhaust manifold heat shield to the manifold. Tighten: Tighten the bolts to 10 N.m (89 lb in).
3. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Remove the bolts securing the center bearing heat shield to the center bearing.
3. Remove the heat shield from the center bearing in the following order: Tilt the heat shield to either side. Slide the heat shield out from between the body, the drive shaft center bearing, and the exhaust pipes. Remove the heat shield from the vehicle.

1. Install the center bearing heat shield to the center bearing in the following order: Slide the heat shield in between the body, the drive shaft center bearing, and the exhaust pipes. Align the holes in the heat shield with the holes in the center bearing.
2. Install the bolts securing the center bearing heat shield to the center bearing. Tighten: Tighten the center bearing heat shield bolts to 8 N.m (71 lb in).
3. Lower the vehicle.

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

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 Gage

Scheme 1

See also:
• Strategy Based Diagnosis
• Hot Exhaust System Caution
• Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1
• Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1
• Exhaust Service Caution
• Protective Goggles and Glove Caution
• Oil Level Indicator and Tube Replacement
• Exhaust Manifold Cleaning and Inspection - Left
• Fastener Notice
• Exhaust Manifold Cleaning and Inspection - Left
• Lifting and Jacking the Vehicle
• Exhaust System Inspection Notice
• Propeller Shaft Replacement - Front
• Symptoms - Engine Exhaust
• Exhaust System Description
• Restricted Exhaust
• Exhaust Leakage
• Exhaust Noise
• Special Tools
• Fastener Tightening Specifications
• Exhaust Hanger Replacement
• Exhaust System Replacement