Catalytic Converter - Universal

This procedure guides you through replacing the factory catalytic converters with universal catalytic converters on a 1992 Dodge Viper 8.0L V10, including oxygen sensor transfer and exhaust system removal.

Warnings

Tools required

Parts

• Universal catalytic converter (driver side) × 1 — Must meet 50-state EPA requirements; select based on inlet/outlet diameter and length to match OEM
• Universal catalytic converter (passenger side) × 1 — Must meet 50-state EPA requirements; select based on inlet/outlet diameter and length to match OEM
• Exhaust clamps or band clamps × 4 — Size to match pipe diameter (typically 2.5" or 3")
• Exhaust flange gaskets × 2 — Use OEM specification or high-temperature graphite gaskets
• Oxygen sensor anti-seize compound × 1 — Nickel-based, sensor-safe formulation
• General anti-seize compound × 1 — Copper or nickel-based for exhaust fasteners

Preparation

1. Park vehicle on level, solid surface and apply parking brake firmly.
2. Place wheel chocks behind rear wheels.
3. Allow exhaust system to cool completely (minimum 2 hours after last operation).
4. Raise front of vehicle with floor jack and support securely on jack stands at manufacturer-specified lift points.
5. Raise rear of vehicle and support securely on jack stands to provide adequate working clearance under entire exhaust system.
6. Spray all exhaust flange bolts, oxygen sensor threads, and hanger fasteners with penetrating oil. Allow to soak while preparing tools.
7. Verify replacement universal catalytic converters are correct diameter and approximate length to fit between cut points.

Procedure

1. 1

   Disconnect battery negative terminal
   Disconnect the negative battery terminal to prevent oxygen sensor fault codes during removal. Use a 10mm wrench to loosen the terminal clamp nut and remove the cable from the battery post. Secure cable away from battery.
2. 2

   Remove oxygen sensors
   The 1992 Viper is equipped with oxygen sensor(s) upstream of the catalytic converters; verify the exact quantity and location against factory service documentation before removal. Disconnect the oxygen sensor electrical connectors by releasing the locking tabs and separating the connectors. Using an oxygen sensor socket or 22mm deep offset wrench, remove each oxygen sensor by turning counterclockwise. Note the installed depth and position of each sensor. Inspect sensor threads and replace sensors if threads are damaged or sensors show signs of contamination.
   ⚠Oxygen sensors may seize in the exhaust manifold or pipe. Apply moderate force; if resistance is excessive, apply additional penetrating oil and heat with a propane torch (avoiding the sensor body) before retrying.
3. 3

   Remove heat shields
   Remove any heat shields protecting the catalytic converters. These are typically secured with several bolts around the perimeter. Use the appropriate socket to remove the heat shield bolts and set heat shields aside. Note the positions of any spacers or brackets for reinstallation.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
4. 4

   Disconnect exhaust at flanges
   Locate the connection points joining the catalytic converters to the exhaust headers upstream and to the exhaust pipes downstream. NOTE: The 1992 Viper uses side-exit exhaust routed through the rocker sills; verify the actual flange/joint locations before disassembly. Remove the flange bolts or clamps at each connection point using the appropriate socket. Support the exhaust components as fasteners are removed to prevent sudden dropping.vent sudden dropping.
   ⚠Exhaust components will be loose once flange bolts are removed. Support pipes and converters with a jack or helper to prevent damage to hangers or other components.
   Torque spec

   Exhaust Flange Bolt33 Nm (24 lb-ft)
5. 5

   Remove exhaust hangers
   Disconnect the rubber exhaust hangers supporting the catalytic converter section. Use an exhaust hanger removal tool or pry bar to work the rubber isolators off their mounting studs. There are typically 2 hangers per side on this exhaust system supporting the converter section. Note the hanger positions for reinstallation.
6. 6

   Remove factory catalytic converter assembly
   With all fasteners and hangers disconnected, carefully lower and remove the factory catalytic converter assembly from the vehicle. This may be a single assembly or separate sections per bank. Maneuver the assembly past suspension components and exhaust routing. Place the factory converters aside on a safe surface.
7. 7

   Measure and mark cut locations
   With the factory converters removed, measure the inlet and outlet pipe diameters and the overall length of each converter section. Measure the universal converters to determine where cuts must be made in the existing exhaust pipes to accommodate the new units. Mark cut locations on the remaining exhaust pipes (manifold downpipes and intermediate pipes) using a marker or soapstone. The universal converters should fit with minimal gap at each joint. Allow approximately 2-3 inches of overlap on each end for clamping or welding.
8. 8

   Cut exhaust pipes
   Using a reciprocating saw with a metal-cutting blade or an exhaust pipe cutter, carefully cut the exhaust pipes at the marked locations. Make cuts as straight and perpendicular to the pipe axis as possible to ensure good clamping surface. Debur the cut edges with a file or wire wheel to remove sharp edges and create a smooth surface for clamp installation.
   ⚠Wear eye protection when cutting exhaust pipes. Metal shavings and debris will be ejected during cutting.
9. 9

   Test-fit universal catalytic converters
   Slide the universal catalytic converters into position between the cut pipe ends. Verify proper fit, orientation, and clearance from suspension components, driveshaft, and body panels. The converter inlet should face the engine (upstream) and outlet should face the rear (downstream). Adjust cut locations if necessary to achieve proper fit. Ensure oxygen sensor bungs are positioned for easy sensor access and proper routing of sensor wires.
10. 10

    Install universal catalytic converters
    Position the first universal catalytic converter between the cut pipes. Slide exhaust clamps or band clamps over the pipe joints (one clamp per joint end). Align the converter so there is equal overlap on both ends and adequate clearance from all surrounding components. Reconnect the exhaust hangers to support the new converter assembly. Tighten the exhaust clamps gradually and evenly, alternating between upstream and downstream clamps to center the converter. Do not fully tighten clamps yet. Repeat for the second catalytic converter on the opposite bank.
    ℹ️Leave clamps slightly loose until both converters are installed and aligned to allow for final adjustment.
11. 11

    Align exhaust system
    With both universal catalytic converters loosely installed, check the entire exhaust system alignment. Verify adequate clearance (minimum 1 inch) from the driveshaft, suspension components, fuel lines, brake lines, and body panels throughout the full range of suspension travel. Adjust converter positions as needed by loosening clamps and shifting components. Ensure exhaust hangers are properly seated and not under excessive tension.
12. 12

    Tighten exhaust clamps
    Once alignment is verified, tighten all exhaust clamps securely. Tighten clamps evenly to the clamp manufacturer's specified torque (band clamp torque varies significantly by size and type — always follow the specific clamp manufacturer's instructions rather than a generic value). Recheck alignment after tightening to ensure components did not shift during final tightening.
13. 13

    Reinstall oxygen sensors
    Apply a thin coat of oxygen sensor-safe anti-seize compound to the threads of each oxygen sensor (avoid getting compound on the sensor tip). Thread each oxygen sensor into its bung by hand to avoid cross-threading, then tighten to specification using the oxygen sensor socket or 22mm wrench. Reconnect the oxygen sensor electrical connectors, ensuring the locking tabs engage fully.
    ⚠Use only sensor-safe nickel-based anti-seize on oxygen sensor threads. Standard copper anti-seize can contaminate the sensor. Do not apply anti-seize to the sensor tip or allow it to enter the exhaust stream.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
14. 14

    Reinstall heat shields
    Reposition the heat shields over the catalytic converters. Verify heat shields do not contact the converters directly and have adequate clearance. Install and tighten heat shield bolts to specification, ensuring any spacers or brackets are in their original positions.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)
15. 15

    Reconnect battery and perform final inspection
    Reconnect the negative battery terminal and tighten the clamp nut securely. Perform a final visual inspection of all connections, clamps, hangers, and clearances. Verify all tools and parts have been removed from under the vehicle. Lower the vehicle from jack stands carefully.

Reassembly

1. Installation sequence mirrors removal with specific attention to exhaust system alignment and clamp tightening sequence.
2. Oxygen sensors must be installed with sensor-safe anti-seize on threads only, not on sensor elements.
3. Heat shields must be reinstalled to prevent heat damage to surrounding components and to reduce radiant heat into the cabin.

Verification

• Start engine and allow to idle. Listen for exhaust leaks at all clamp joints and flange connections. A leak will produce a distinctive ticking or hissing sound that increases with engine speed.
• With engine at operating temperature, visually inspect all clamp connections for signs of exhaust gas leakage (soot staining).
• Verify adequate exhaust system clearance by having an assistant gently rock the vehicle side-to-side while observing clearances under the vehicle. No contact should occur with suspension, body, or driveline components.
• Check for illuminated check engine light or malfunction indicator lamp. If present, use an OBD-II scanner to retrieve codes. Common post-installation codes include oxygen sensor readiness or catalyst efficiency codes, which may require drive cycles to clear.
• Perform a test drive and verify normal engine performance, no abnormal exhaust noise, and no vibration or rattling from the exhaust system.
• After 50-100 miles of driving, re-inspect all exhaust clamps and retighten if necessary as the system undergoes heat cycling and components settle.

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