Engine Exhaust System Cadillac DTS I

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/dts/i-2005-2011/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/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) .

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/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
2. Poor acceleration-Refer to «Restricted Exhaust»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
3. Poor fuel economy-Refer to «Restricted Exhaust»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
4. Excessive smoke-diesel-Refer to «Restricted Exhaust»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
5. Exhaust hissing noise-Refer to «Exhaust Leakage»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
6. Exhaust popping noise-Refer to «Exhaust Leakage»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system__exhaust-leakage) .
7. Exhaust rattle noise-Refer to «Exhaust Noise»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system__exhaust-noise) .
8. Loud exhaust noise-Refer to «Exhaust Noise»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system__exhaust-noise)
9. Exhaust buzz, groan, hum noise-Refer to «Exhaust Noise»(/cadillac/dts/i-2005-2011/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

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 Gage. See «Special Tools»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .Removing the heated oxygen (HO2S) sensor may set a diagnostic trouble code (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.

Restricted Exhaust

Exhaust Leakage

Exhaust Noise

Removal Procedure

1. Remove the front engine mount bracket. Refer to «Engine Front Mount Bracket Replacement»(/cadillac/dts/i-2005-2011/remont/mechanical/#engine-mechanical-46l-2-of-5) .
2. Remove the connector position assurance (CPA) retainer.
3. Disconnect the engine harness electrical connector (3) from the heated oxygen sensor (HO2S).
4. Remove the HO2S.
5. Remove the exhaust manifold front pipe bolts (2).
6. Remove the exhaust manifold bolts.
7. Remove the exhaust manifold (2).
8. Remove and discard the exhaust manifold gasket (1).
9. Remove and discard the front exhaust manifold pipe seal.
10. Remove the front exhaust manifold pipe flange.

Installation Procedure

1. Install the front exhaust manifold pipe flange and a NEW seal onto the exhaust manifold.
2. Insert the upper right exhaust manifold bolt to the manifold in this location (2).
3. Place the NEW exhaust manifold gasket over the bolt and against the manifold.
4. Insert the exhaust manifold into the front exhaust manifold pipe and against the cylinder head.
5. Finger start the exhaust manifold bolt.
6. Install the remaining exhaust manifold bolts and tighten all exhaust manifold bolts starting from right to left beginning with the bolt in this location (2). Tighten: Tighten the bolts to 25 N.m (18 lb ft).
7. Install the exhaust manifold front pipe bolts (2).
8. If reusing the old HO2S, coat the threads with anti-sieze compound, GM P/N 12377953 or equivalent.
9. Install the HO2S. Tighten: Tighten the sensor to 41 N.m (30 lb ft).
10. Connect the engine harness electrical connector (3) to the HO2S.
11. Install the CPA retainer.
12. Install the front engine mount bracket. Refer to «Engine Front Mount Bracket Replacement»(/cadillac/dts/i-2005-2011/remont/mechanical/#engine-mechanical-46l-2-of-5) .

Special Tools

J 42640 Steering Column Lock Pin. See Special Tools .

1. Remove the connector position assurance (CPA) retainer (3).
2. Disconnect the engine harness electrical connector (2) from the heated oxygen sensor (HO2S).
3. Remove the HO2S clip (5) from the secondary air injection (AIR) valve hose bracket.
4. Lock the steering column by installing the J 42640 into the underside of the steering column. See «Special Tools»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
5. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/dts/i-2005-2011/remont/hoistjack/#general-information__lifting-jacking-the-vehicle) .
6. Remove the rear exhaust manifold pipe. Refer to «Exhaust Manifold Rear Pipe Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
7. Remove the AIR check valve. Refer to «Secondary Air Injection Check Valve Replacement»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2) .
8. Disconnect the engine harness clip (2) from the steering gear heat shield.
9. Disconnect the engine harness clip (3) from the steering gear heat shield.
10. Remove the steering gear heat shield bolts.
11. Remove the steering gear heat shield.
12. Disconnect the electronic suspension position sensor link ball studs (1) from the lower control arms.
13. Unsnap and remove the intermediate shaft seal.
14. Remove the intermediate shaft pinch bolt.
15. Separate the intermediate shaft from the steering gear.
16. Support the rear of the frame with a tall screw type jack.
17. Remove the 4 rearward engine frame-to-body bolts (1).
18. Lower the screw type jack approximately 4 cm (1.5 in) allowing the rear of the engine frame to lower.
19. Remove the HO2S.
20. Remove the exhaust manifold nuts.
21. Remove the exhaust manifold (2).
22. Remove and discard the exhaust manifold gasket (1).

1. Install a NEW exhaust manifold gasket (1) onto the cylinder head studs.
2. Install the exhaust manifold (2).
3. Install the exhaust manifold nuts. Tighten: Tighten the nuts to 25 N.m (18 lb ft).
4. If reusing the old HO2S, coat the threads with anti-sieze compound, GM P/N 12377953 or equivalent.
5. Install the HO2S. Tighten: Tighten the sensor to 41 N.m (30 lb ft).
6. Raise the engine frame into position.
7. Install the 4 rearward engine frame-to-body bolts (1). Tighten: Tighten the bolts to 191 N.m (141 lb ft).
8. Remove the screw type jack.
9. Connect the intermediate shaft to the steering gear.
10. Install the intermediate shaft pinch bolt. Tighten: Tighten the bolt to 45 N.m (33 lb ft).
11. Install the intermediate shaft seal.
12. Connect the electronic suspension position sensor link ball studs (1) to the lower control arms.
13. Install the steering gear heat shield.
14. Install the steering gear heat shield bolts. Tighten: Tighten the bolts to 9 N.m (80 lb in).
15. Connect the engine harness clip (3) to the steering gear heat shield.
16. Connect the engine harness clip (2) to the steering gear heat shield.
17. Install the AIR check valve. Refer to «Secondary Air Injection Check Valve Replacement»(/cadillac/dts/i-2005-2011/remont/testing-diagnostics/#engine-control-system-fuel-system-46l-introduction-2-of-2) .
18. Install the rear exhaust manifold pipe. Refer to «Exhaust Manifold Rear Pipe Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
19. Lower the vehicle.
20. Remove the J 42640 from the steering column. See «Special Tools»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
21. Connect the engine harness electrical connector (2) to the HO2S.
22. Install the HO2S clip (5) to the AIR valve hose bracket.
23. Install the CPA retainer (3).

1. Remove the rear exhaust manifold pipe. Refer to «Exhaust Manifold Rear Pipe Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
2. Remove the transaxle. Refer to «Transmission Replacement»(/cadillac/dts/i-2005-2011/remont/automatic-trans/#how-to-overhaul-the-automatic-transaxle-4t80-e-removal-installation-service-troubleshooting-diagnosis__transmission-replacement) .
3. Remove the front exhaust pipe to exhaust manifold bolts (2).
4. Disconnect the EGR inlet pipe nut from the front exhaust manifold pipe.
5. Remove the front exhaust manifold pipe to lower crankcase bolt.
6. Remove the front exhaust manifold pipe to cylinder head stud.
7. Remove the front exhaust manifold pipe.
8. Remove the front exhaust manifold pipe seal from the left exhaust manifold and discard the seal.
9. Remove the exhaust manifold flange retainer.

1. Place the retainer and a NEW front exhaust manifold pipe seal over the left exhaust manifold.
2. Insert the front exhaust manifold pipe over the left exhaust manifold.
3. Install the front exhaust manifold pipe to cylinder head stud. Tighten: Tighten the stud to 25 N.m (18 lb ft).
4. Install the front exhaust manifold pipe to lower crankcase bolt. Tighten: Tighten the bolt to 25 N.m (18 lb ft).
5. Connect the EGR inlet pipe nut to the front exhaust manifold pipe. Tighten: Tighten the nut to 60 N.m (44 lb ft).
6. Install the front exhaust pipe to exhaust manifold bolts (2). Tighten: Tighten the bolts to 25 N.m (18 lb ft).
7. Install the transaxle. Refer to «Transmission Replacement»(/cadillac/dts/i-2005-2011/remont/automatic-trans/#how-to-overhaul-the-automatic-transaxle-4t80-e-removal-installation-service-troubleshooting-diagnosis__transmission-replacement) .
8. Install the rear exhaust manifold pipe. Refer to «Exhaust Manifold Rear Pipe Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/dts/i-2005-2011/remont/hoistjack/#general-information__lifting-jacking-the-vehicle) .
2. Remove the catalytic converter to rear exhaust manifold pipe nuts.
3. Position the exhaust system rearward, enough to allow the studs located in the catalytic converter to clear the rear exhaust manifold pipe.
4. Remove and discard the catalytic converter gasket.
5. Remove the rear exhaust manifold pipe to the right exhaust manifold bolts.
6. Remove the rear exhaust manifold pipe to the front exhaust manifold pipe bolts.
7. Remove and discard the rear exhaust manifold pipe gasket.
8. Remove and discard the rear exhaust manifold pipe seal.
9. Remove the rear exhaust manifold pipe flange.

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

1. Install the following components to the rear exhaust manifold pipe. Position a NEW rear exhaust manifold pipe seal and the rear exhaust manifold pipe flange to the rear exhaust manifold pipe. Insert and snug the 2 rear exhaust manifold pipe to flange bolts. Insert the 2 rear exhaust manifold pipe to exhaust manifold bolts. Place a NEW rear exhaust manifold pipe to exhaust manifold gasket onto the bolts.
2. Install and position the rear exhaust manifold pipe to the front exhaust manifold pipe and exhaust manifold.
3. Tighten the rear exhaust manifold pipe to exhaust manifold bolts. Tighten: Tighten the bolts to 40 N.m (30 lb ft).
4. Tighten the rear exhaust manifold pipe to front exhaust manifold pipe bolts. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
5. Place a NEW catalytic converter gasket over the catalytic converter studs.
6. Position the catalytic converter to the rear exhaust manifold pipe.
7. Install the catalytic converter to the rear exhaust manifold pipe. Tighten: Tighten the nuts to 25 N.m (18 lb ft).
8. Lower the vehicle.

1. Remove the oxygen sensor wiring harness heat shield. Refer to «Oxygen Sensor Wiring Harness Heat Shield Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
2. Remove the connector position assurance (CPA) retainer.
3. Disconnect the heated oxygen sensor (HO2S) electrical connector.
4. Remove the HO2S.
5. Remove the catalytic converter to the rear exhaust manifold pipe nuts.
6. Suitably support the exhaust system.
7. Remove the exhaust hanger to the rear suspension support bracket bolts.
8. Remove the rear exhaust hanger to hanger bracket nuts.
9. Remove the rear exhaust hanger bracket to the rear compartment side rail bolts.
10. With the aid of an assistant, lower the exhaust system.
11. Remove and discard the catalytic converter gasket.

Note. Refer to Exhaust System Inspection Notice .

1. With the aid of an assistant, raise the exhaust system.
2. Install the rear exhaust hanger to hanger bracket studs.
3. Install the rear exhaust hanger to hanger bracket nuts. Tighten: Tighten the nuts to 30 N.m (22 lb ft).
4. Install a NEW catalytic converter gasket onto the studs.
5. Install the catalytic converter to the rear exhaust manifold pipe.
6. Install and snug the catalytic converter to the rear exhaust manifold pipe nuts.
7. Install the rear exhaust hanger bracket to the rear compartment side rail bolts. Tighten: Tighten the bolts to 50 N.m (37 lb ft).
8. Install the exhaust hanger to the rear suspension support bracket bolts. Tighten: Tighten the bolts to 30 N.m (22 lb ft).
9. Tighten the catalytic converter to the rear exhaust manifold pipe nuts previously installed. Tighten: Tighten the nuts to 25 N.m (18 lb ft).
10. If reusing the old HO2S, coat the threads with anti-seize compound, GM P/N 12377953 or equivalent.
11. Install the HO2S. Tighten: Tighten the sensor to 41 N.m (30 lb ft).
12. Connect the HO2S electrical connector.
13. Install the CPA retainer.
14. Install the oxygen sensor wiring harness heat shield. Refer to «Oxygen Sensor Wiring Harness Heat Shield Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/dts/i-2005-2011/remont/hoistjack/#general-information__lifting-jacking-the-vehicle) .
2. Support the exhaust system near the resonator with a suitable jack.
3. Remove the oxygen sensor. It is not necessary to disconnect the electrical connector.
4. Remove the nuts securing the catalytic converter to the exhaust manifold pipe.
5. Remove the bolts securing the center exhaust hangers to the rear suspension support brackets.
6. Remove the catalytic converter from the manifold pipe.
7. Lower the exhaust system.
8. Remove the catalytic converter gasket (1). Do not reuse the gasket.
9. Cut the intermediate pipe 34 mm (1.3 in) from the resonator weld.

1. Slide 2 service clamps (1) over the catalytic converter assembly outlet pipe. Do not tighten at this time.
2. Slide the catalytic converter assembly (1) outlet pipe over the intermediate pipe (2).
3. Place a NEW catalytic converter gasket over the catalytic converter studs.
4. Raise the exhaust system into position, aligning the catalytic converter with the exhaust manifold pipe.
5. Install the nuts securing the catalytic converter to the exhaust manifold pipe. Do not tighten at this time.
6. Install the bolts securing the center exhaust hangers to the rear suspension support brackets. Tighten: Tighten the center exhaust hanger bolts to 30 N.m (22 lb ft).
7. Tighten the catalytic converter nuts. Tighten: Tighten the catalytic converter nuts in a crisscross pattern to 25 N.m (18 lb ft).
8. Remove the jack from under the vehicle.
9. Position the service clamps midway on the catalytic converter assembly outlet pipe, as close together as possible.
10. Rotate the clamps so the fastening ends are pointing in opposite directions. Tighten: Tighten the service clamps to 54 N.m (40 lb ft).
11. Lower the vehicle.
12. Check the exhaust system for leaks.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/dts/i-2005-2011/remont/hoistjack/#general-information__lifting-jacking-the-vehicle) .
2. Remove the exhaust hanger to the rear suspension support bracket bolt.
3. Apply a suitable lubricant to the exhaust hanger rod in order to ease the removal of the hanger.
4. Pull outward on the exhaust hanger in order to remove it from the exhaust pipe hanger rod.
5. Remove the rear exhaust hanger to hanger bracket nut.
6. Apply a suitable lubricant to the rear hanger rod in order to ease the removal of the hanger.
7. Pull outward on the rear exhaust hanger in order to remove it from the tail pipe hanger rod.

1. Apply a soapy solution to the rear hanger rod and the inner diameter of the rear exhaust hanger in order to ease the installation of the hanger.
2. Press the rear exhaust hanger over the tail pipe hanger rod.
3. Position the rear exhaust hanger to the rear exhaust hanger bracket.
4. Install the rear exhaust hanger to hanger bracket nut. Tighten: Tighten the nut to 30 N.m (22 lb ft).
5. Apply a soapy solution to the exhaust pipe hanger rod and the inner diameter of the center exhaust hanger in order to ease the installation of the hanger.
6. Press the exhaust hanger over the exhaust pipe hanger rod.
7. Install the exhaust hanger to the rear suspension support bracket bolt. Tighten: Tighten the bolt to 30 N.m (22 lb ft).
8. Lower the vehicle.

1. Remove the exhaust system. Refer to «Exhaust System Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .
2. Drill out the heat shield rivets (2).
3. Remove the heat shield.

1. Position the heat shield to the floor panel.
2. Using a rivet gun, install the rivets (2), except for this location (1), this rivet will be installed with the oxygen sensor heat shield.
3. Install the exhaust system. Refer to «Exhaust System Replacement»(/cadillac/dts/i-2005-2011/remont/exhaust/#engine-exhaust-system) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/dts/i-2005-2011/remont/hoistjack/#general-information__lifting-jacking-the-vehicle) .
2. Drill out the rivets.
3. Lower the heat shield until the heated oxygen sensor (HO2S) clips can be disconnected.
4. Disconnect the HO2S clips from the heat shield.
5. Remove the heat shield.

1. Raise the heat shield until the HO2S clips can be connected.
2. Connect the HO2S clips to the heat shield.
3. Position the heat shield to the floor panel.
4. Using a rivet gun, install the rivets.
5. 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. Platium (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.

Illustration Tool Number/Description J 35314-A Exhaust Back Pressure Gage J 42640 Steering Column Anti-rotation Pin

Scheme 1

Scheme 2

See also:
• Strategy Based Diagnosis
• Hot Exhaust System Caution
• Heated Oxygen Sensor Replacement - Bank 1 Sensor 1
• Exhaust Service Caution
• Protective Goggles and Gloves Caution
• Engine Front Mount Bracket Replacement
• Fastener Notice
• Lifting and Jacking the Vehicle
• Transmission Replacement
• Flex Decoupler Notice
• Exhaust System Inspection Notice
• Symptoms - Engine Exhaust
• Exhaust System Description
• Restricted Exhaust
• Exhaust Leakage
• Exhaust Noise
• Fastener Tightening Specifications