Exhaust Manifold

Remove and replace the exhaust manifolds on a 2008 Dodge Viper 8.4L V10, requiring access from above and below the vehicle with drivetrain components moved for clearance.

Warnings

Tools required

Parts

• Exhaust manifold gasket set (left and right) × 1 — Use OEM specification
• Exhaust manifold hardware kit (studs and nuts) × 1 — Use OEM specification
• Oxygen sensor anti-seize compound × 1 — High-temperature anti-seize

Preparation

1. Park vehicle on level surface and allow engine to cool completely (minimum 4 hours after operation)
2. Disconnect negative battery cable
3. Raise vehicle and secure on jack stands rated for vehicle weight
4. Remove engine under-tray if equipped
5. Apply penetrating oil to all exhaust manifold fasteners and oxygen sensor threads, allow to soak 30 minutes minimum

Procedure

1. 1

   Remove oxygen sensors
   Using an oxygen sensor socket, carefully remove the upstream oxygen sensor(s) located at each exhaust manifold. Verify exact sensor count and location against the service manual for this vehicle. Label sensors by bank and position for reinstallation. Label sensors by bank and position for reinstallation. Inspect sensor threads and clean if necessary. Do not allow sensors to hang by their wiring.
2. 2

   Disconnect exhaust pipes from manifolds
   Working from underneath the vehicle, locate the flange connections where the exhaust pipes mate to the manifolds. Remove the nuts securing each exhaust pipe flange to its respective manifold (verify exact count per flange against the service manual). Support the exhaust system with a jack or hanger to prevent stress on downstream components. Separate the flanges and set aside the gaskets.
3. 3

   Remove engine cover and air intake components
   From the engine bay, remove the engine cover by releasing any clips or fasteners. Remove the air intake assembly to improve access to the rear cylinders. This typically includes the air filter housing, intake tubing, and any resonators. Disconnect any vacuum lines or sensors attached to the intake system and label for reinstallation.
4. 4

   Disconnect heat shields
   Remove the heat shields covering the exhaust manifolds. Each heat shield is secured with multiple fasteners around the perimeter. Remove all fasteners securing the heat shields and carefully work the shields free from the manifold studs. Some shields may be multi-piece assemblies.
5. 5

   Remove spark plug wires from affected cylinders
   For improved access to manifold fasteners, remove spark plug wires from cylinders adjacent to the manifold fasteners being accessed. On this V10, you may need to remove wires from the cylinders on the bank served by the manifold being accessed. Confirm the exact cylinder-to-bank assignment against the service manual before removal. Label each wire with its cylinder number. Label each wire with its cylinder number.
6. 6

   Access and remove left (driver side) manifold fasteners
   Working from above and below, locate all fasteners securing the left exhaust manifold to the cylinder head (verify exact count against the service manual before beginning). Using a combination of extensions, universal joints, and socket wrenches, remove each fastener in a crisscross pattern from the center outward. Some fasteners will be accessed from above, others from below. Use a breaker bar if fasteners are seized. Keep track of all fasteners and note any studs that break during removal.
   ⚠Rear-most fasteners require an 18-inch extension and universal joint. Work patiently to avoid rounding fastener heads.
7. 7

   Remove left exhaust manifold
   With all fasteners removed, carefully work the left manifold free from the cylinder head studs. The manifold is heavy and awkward to maneuver in the tight engine bay. You may need to rotate and angle the manifold to clear engine components and the frame rail. Lower the manifold down and out through the bottom of the vehicle if necessary.
8. 8

   Access and remove right (passenger side) manifold fasteners
   Repeat the process for the right exhaust manifold. Locate all fasteners securing the right manifold to the cylinder head (verify exact count against the service manual before beginning). On the right side, access may be complicated by the frame rail and steering components. Remove each fastener in a crisscross pattern from the center outward using appropriate extensions and universal joints.
   ⚠The right side typically has more restricted access than the left. Take extra care to avoid damaging adjacent components.
9. 9

   Remove right exhaust manifold
   With all fasteners removed, carefully work the right manifold free from the cylinder head studs. Maneuver the manifold to clear all obstructions and remove it from the vehicle. Again, removal may be easier from below.
10. 10

    Inspect and clean cylinder head mating surfaces
    With both manifolds removed, thoroughly inspect all cylinder head exhaust ports and mating surfaces. Use a gasket scraper to remove all old gasket material without scratching the machined surfaces. Use a wire brush to clean the manifold mounting studs. Inspect studs for damage or stripped threads. Replace any broken or damaged studs using the appropriate stud removal and installation tools. Check for any cracks or damage to the cylinder head ports.
11. 11

    Prepare new or refurbished manifolds
    If installing new manifolds, remove any protective coatings or shipping materials. If reusing manifolds, have them inspected for cracks and warpage. Clean all mating surfaces thoroughly. Install new exhaust manifold gaskets onto the cylinder head studs, ensuring proper alignment with the exhaust ports. The gaskets should fit snugly over the studs and seat flat against the head.
12. 12

    Install right exhaust manifold
    Carefully position the right exhaust manifold onto the cylinder head studs, aligning it with the gasket. Maneuver the manifold into position using the reverse of the removal path. Once seated, start all 10 fasteners by hand to ensure proper thread engagement. Using a torque wrench, tighten the fasteners in a crisscross pattern from the center outward in three stages: first to one-third final torque, then two-thirds, then final torque as specified in the service manual.
13. 13

    Install left exhaust manifold
    Position the left exhaust manifold onto the cylinder head studs with its gasket. Align and seat the manifold, then start all 10 fasteners by hand. Torque the fasteners in a crisscross pattern from center outward in three progressive stages to the specified torque value.
14. 14

    Reconnect exhaust pipes
    From underneath the vehicle, install new exhaust flange gaskets between the manifolds and exhaust pipes. Align the exhaust pipe flanges to the manifold outlets and start all 6 flange nuts by hand. Torque the nuts evenly in a crisscross pattern to ensure even sealing and prevent exhaust leaks.
15. 15

    Reinstall oxygen sensors and remaining components
    Apply a thin coat of high-temperature anti-seize compound to the threads of each oxygen sensor (avoid getting compound on the sensor tip). Install each oxygen sensor into its original position, torquing to specification. Reconnect all oxygen sensor electrical connectors. Reinstall heat shields with all fasteners. Reinstall spark plug wires to their labeled cylinders. Reinstall air intake assembly, engine cover, and any removed brackets or components. Reinstall engine under-tray.

Reassembly

1. Ensure all electrical connectors are properly seated and secured
2. Double-check that all exhaust manifold fasteners are torqued to specification
3. Verify oxygen sensors are not cross-threaded and connectors are locked
4. Ensure spark plug wires are fully seated on spark plugs
5. Reconnect negative battery cable

Verification

• Start engine and listen for any exhaust leaks at manifold-to-head and manifold-to-pipe joints
• Allow engine to reach operating temperature and inspect all connections for leaks
• Check for any unusual engine noises or vibrations
• Verify all oxygen sensor codes are clear using a scan tool
• Perform a test drive to confirm proper engine operation under load
• Re-inspect all fasteners after first heat cycle and re-torque if necessary

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