Intermediate Pipe

This procedure covers the removal and replacement of the intermediate exhaust pipe on the 2007-2013 Mercedes-Benz S65 AMG with the 6.0L V12 BiTurbo M275 engine.

Warnings

Tools required

Parts

• Intermediate exhaust pipe × 1 — Use OEM specification
• Exhaust flange gaskets (front connection) × 2 — Use OEM specification
• Exhaust flange gaskets (rear connection) × 2 — Use OEM specification
• Exhaust mounting hardware kit × 1 — Replace if corroded

Preparation

1. Ensure exhaust system is completely cold to the touch
2. Raise vehicle on lift or secure on jack stands at proper lift points
3. Spray all exhaust flange bolts, hanger bolts, and O2 sensor threads with penetrating oil and allow to soak for 15-20 minutes
4. Inspect work area and ensure adequate clearance to maneuver exhaust components
5. Have fire extinguisher nearby in case penetrating oil ignites on hot surfaces

Procedure

1. 1

   Remove heat shields
   Locate and remove any heat shields covering the intermediate pipe area using a 10mm socket. These shields may be above or below the exhaust components. Keep track of bracket locations for reinstallation.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
2. 2

   Disconnect oxygen sensors
   Disconnect the electrical connectors for any oxygen sensors mounted in the intermediate pipe. Using a 22mm oxygen sensor socket or deep socket, carefully unthread the O2 sensors from the pipe. If sensors are being reused, handle with care to avoid damaging the sensor element. Set sensors aside in a safe location.
   ⚠Do not allow O2 sensors to hang by their wiring. Support the sensors to prevent wire damage.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
3. 3

   Support intermediate pipe
   Position a jack stand or have an assistant support the weight of the intermediate pipe before disconnecting mounting points. The pipe assembly is heavy and will drop when hangers are released.
   ⚠Intermediate pipe sections can weigh 30-40 lbs each and may shift unexpectedly when disconnected.
4. 4

   Remove exhaust hangers
   Locate the rubber exhaust hangers supporting the intermediate pipe. Using an exhaust hanger removal tool or pry bar, carefully work each hanger off its mounting bracket. Note the orientation and position of hangers for reassembly. There are typically 2-3 hangers per side on this vehicle.
   Torque spec

   Hanger Bolts27 Nm (20 lb-ft)
5. 5

   Disconnect front flange connection
   Locate the front flange connection between the catalytic converter (or downpipe) and the intermediate pipe. Using a 17mm socket, remove the flange bolts connecting these components. There should be 3-4 bolts at this connection. Once bolts are removed, separate the flange and remove the old gasket.
   ⚠Flange bolts may be severely corroded. Apply heat carefully if bolts will not break free, or use bolt extractor if heads strip.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
6. 6

   Disconnect rear flange connection
   Move to the rear flange connection between the intermediate pipe and the rear muffler section. Using a 17mm socket, remove the flange bolts at this junction. Separate the flange connection and remove the old gasket. The intermediate pipe should now be free from the vehicle.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
7. 7

   Remove intermediate pipe
   Carefully lower and maneuver the intermediate pipe out from under the vehicle. Watch for any remaining brackets or interference points. Inspect the removed pipe for damage, cracks, or excessive corrosion to confirm replacement was necessary.
8. 8

   Clean flange surfaces
   Using a wire brush and scraper, thoroughly clean all flange mating surfaces on both the upstream and downstream connections. Remove all old gasket material, carbon deposits, and corrosion. Surfaces must be flat and clean for proper sealing.
9. 9

   Prepare new intermediate pipe
   Unpack the new intermediate pipe and inspect for shipping damage. Install new flange gaskets onto both the front and rear connection points. If reusing oxygen sensors, apply a thin coat of anti-seize compound to the threads only (never on the sensor tip) and thread sensors into the new pipe hand-tight first.
   ⚠Never apply anti-seize or any compound to the oxygen sensor element itself, only to the threads.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
10. 10

    Install intermediate pipe
    Maneuver the new intermediate pipe into position under the vehicle. Align the pipe with both front and rear flange connections. Start all flange bolts hand-tight before final tightening. Ensure the pipe is properly positioned in relation to exhaust hangers and underbody components.
    ℹ️Do not fully tighten any connections until all bolts are started and pipe alignment is verified.
11. 11

    Torque front flange connection
    Apply anti-seize compound to the threads of the front flange bolts. Install new bolts if originals are corroded. Torque the front flange bolts in a crisscross pattern to ensure even pressure on the gasket.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
12. 12

    Torque rear flange connection
    Torque the rear flange bolts in a crisscross pattern. Verify gasket is seated properly and flange faces are flush before final tightening.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
13. 13

    Install exhaust hangers
    Reinstall all rubber exhaust hangers to their mounting brackets. Ensure the pipe is properly supported and has adequate clearance from underbody components, fuel lines, and brake lines. If hangers have bolts, torque to specification.
    Torque spec

    Hanger Bolts27 Nm (20 lb-ft)
14. 14

    Install oxygen sensors and heat shields
    If not already installed, torque oxygen sensors to specification with anti-seize on threads only. Reconnect all O2 sensor electrical connectors ensuring they click into place. Reinstall heat shields and torque mounting bolts.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Verify all exhaust connections are tight and properly torqued
2. Check that exhaust pipe has adequate clearance from fuel lines, brake lines, suspension components, and underbody panels (minimum 1 inch clearance recommended)
3. Ensure all oxygen sensor connectors are properly seated and secured
4. Verify rubber hangers are properly seated and not torn or damaged

Verification

• Start engine and listen for exhaust leaks at all flange connections while engine is cold
• Allow engine to reach operating temperature and recheck for leaks as exhaust system expands
• Check for any rattles, vibrations, or contact between exhaust and underbody components
• Verify no warning lights are illuminated on the instrument cluster (particularly check engine light from O2 sensors)
• Perform a test drive and listen for any abnormal exhaust noises during acceleration and deceleration
• After test drive, perform final visual inspection underneath vehicle for any signs of leaks, contact points, or loose connections

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