Flex Pipe

Replacement of the exhaust flex pipe section on the 2005 Dodge Viper 8.3L V10, requiring access from underneath the vehicle and potential oxygen sensor removal.

Warnings

Tools required

Parts

• Exhaust flex pipe assembly × 1 — Use OEM specification or equivalent aftermarket
• Exhaust flange gaskets × 2 — Use OEM specification
• Oxygen sensor (if damaged during removal) × 1 — Use OEM specification

Preparation

1. Ensure engine and exhaust system are completely cool to the touch
2. Park vehicle on level, solid surface and engage parking brake
3. Place wheel chocks behind rear wheels
4. Raise front of vehicle with floor jack and secure on jack stands at manufacturer-specified lift points
5. Raise rear of vehicle and secure on jack stands for improved access and clearance
6. Spray all exhaust flange bolts, clamps, and oxygen sensor threads with penetrating oil and allow to soak for 15-20 minutes
7. Disconnect negative battery terminal to prevent accidental oxygen sensor heater circuit faults during removal

Procedure

1. 1

   Locate and inspect flex pipe section
   Position yourself under the vehicle with adequate lighting. Locate the flex pipe section in the exhaust system. On the 2005 Viper, verify the actual flex pipe location against the vehicle's specific dual-exhaust routing, as it may differ from conventional layouts. Inspect the flex pipe for cracks, separation, or excessive corrosion. Note the position of any oxygen sensors in or near the flex pipe section, as these will need removal for access.
2. 2

   Remove upstream oxygen sensor
   Disconnect the oxygen sensor electrical connector by pressing the release tab and pulling apart. Using an oxygen sensor socket or 22mm wrench, carefully unthread the upstream oxygen sensor(s) from the exhaust pipe(s) ahead of the flex section. Note that the V10 uses separate exhaust banks, so multiple upstream sensors may require removal for access. Rotate counterclockwise while supporting the sensor to prevent wiring damage. If sensor is seized, apply additional penetrating oil and allow to soak, or use gentle heat from a propane torch on the bung (not the sensor itself).
   ⚠Do not allow oxygen sensor to hang by its wiring harness. Support the sensor body during removal to prevent internal damage.
3. 3

   Support exhaust system
   Identify the rubber exhaust hangers supporting the exhaust system in the flex pipe area. Place a floor jack with a block of wood under the exhaust pipe behind the flex pipe section to support the weight of the downstream exhaust during flex pipe removal. Raise jack just enough to take tension off the hangers but not to lift the vehicle.
4. 4

   Remove upstream flange connection
   Locate the upstream exhaust flange connection where the flex pipe connects to the front exhaust pipe or manifold collector. Remove the flange bolts securing this connection using the appropriate socket (verify exact bolt count against OEM documentation, typically 2 or 3). If bolts are corroded and spinning, use a cutting tool or bolt extractor as needed. Separate the flange connection and remove the old flange gasket.
   ⚠Corroded flange bolts may break during removal. If bolts break flush with flange, drilling and extraction may be required.
5. 5

   Remove downstream flange connection
   Locate the downstream exhaust flange connection where the flex pipe connects to the catalytic converter or mid-pipe section. Remove the flange bolts securing this connection (verify exact bolt count against OEM documentation, typically 2 or 3). Separate the flange connection and remove the old flange gasket. Inspect both flanges for warping or damage that would prevent proper sealing with the new flex pipe.
6. 6

   Remove exhaust hangers
   Identify any rubber exhaust hangers directly supporting the flex pipe section. Using an exhaust hanger removal tool or pry bar, carefully work the hanger loops off their mounting brackets. Note the exact position and orientation of hangers for reinstallation.
7. 7

   Remove flex pipe assembly
   With both flanges disconnected and hangers removed, carefully maneuver the old flex pipe assembly out from under the vehicle. You may need to lower the support jack slightly to gain clearance. Avoid allowing sharp edges to contact fuel lines, brake lines, or wiring harnesses during removal.
8. 8

   Clean flange surfaces and inspect
   Using a wire brush, thoroughly clean both exhaust flange mating surfaces on the front pipe and rear pipe sections. Remove all old gasket material, carbon deposits, and corrosion. Inspect flanges for cracks, warping, or damaged bolt holes. Check that flange faces are flat and will provide proper sealing with new gaskets. Inspect oxygen sensor bung threads in the front pipe section and clean with a thread chaser if needed.
9. 9

   Prepare new flex pipe assembly
   Unpack the new flex pipe assembly and verify it matches the original in length, flange orientation, and oxygen sensor bung location. Apply a thin coat of anti-seize compound to the oxygen sensor threads. If the flex pipe includes new hardware, verify you have the correct flange bolts and gaskets.
10. 10

    Install new flex pipe assembly
    Position the new flex pipe assembly under the vehicle, aligning it with the upstream and downstream flange connections. Install new flange gaskets on both connections with the gasket orientation matching the flange bolt hole alignment. Maneuver the flex pipe into position, ensuring adequate clearance from surrounding components, fuel lines, brake lines, and heat shields.
11. 11

    Reinstall exhaust hangers
    Work the rubber exhaust hanger loops back onto their mounting brackets in the exact positions noted during removal. Ensure hangers are fully seated and supporting the exhaust system without excessive tension or misalignment. The exhaust should hang naturally without binding or contact with the chassis.
12. 12

    Install and torque flange connections
    Install flange bolts at both the upstream and downstream connections, starting threads by hand to ensure proper alignment. Once both connections are hand-tight, use a torque wrench to tighten all flange bolts to specification in a cross-pattern (alternating bolts to ensure even clamping). Verify flanges are pulled together evenly with no gaps.
13. 13

    Reinstall oxygen sensor
    Thread the oxygen sensor into the bung in the exhaust pipe ahead of the flex section by hand, ensuring threads engage properly without cross-threading. Tighten the oxygen sensor to specification using an oxygen sensor socket or 22mm wrench. Do not overtighten, as this can damage the sensor or bung threads. Reconnect the oxygen sensor electrical connector, ensuring it clicks securely into place.
    ⚠Never apply anti-seize to oxygen sensor threads if sensor has pre-applied coating. Check sensor specifications before applying anti-seize.
    Torque spec

    O2 Sensor47 Nm (35 lb-ft)
14. 14

    Inspect installation and clearances
    Visually inspect the entire flex pipe installation, verifying all flange connections are tight, hangers are properly seated, and there is adequate clearance between the exhaust system and all surrounding components (fuel lines, brake lines, wiring, chassis, suspension components). Ensure no part of the exhaust is resting against the chassis or rubbing on heat shields. Remove the support jack from under the exhaust system.
15. 15

    Reconnect battery and lower vehicle
    Reconnect the negative battery terminal. Carefully lower the vehicle from jack stands to the ground. Remove jack stands and floor jack, then remove wheel chocks.

Reassembly

1. Reinstallation follows removal in reverse order
2. Always use new flange gaskets; do not reuse old gaskets
3. Ensure oxygen sensor connector is fully seated and secured away from heat sources
4. Verify all exhaust hangers are properly engaged and supporting the system

Verification

• Start engine and allow to idle, listening for exhaust leaks at both flange connections and around the flex pipe
• With engine running, have an assistant rev engine to 2000-3000 RPM while you check for exhaust leaks from underneath (look for escaping gas or soot marks)
• Check for exhaust odors in the cabin during test drive, which would indicate a leak
• Verify no exhaust components are contacting the chassis or heat shields during engine operation
• Scan for oxygen sensor diagnostic trouble codes using an OBD-II scanner to confirm sensor is functioning properly
• After initial test drive (15-20 minutes), allow exhaust to cool and re-check all flange bolt torque values

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