Removing Primary Catalytic Converter On Cylinder Bank 5-8

1. Disconnect the oxygen sensor connector for the oxygen sensor behind the catalytic converter at the water splash panel (follow cable routing) and unclip the cables from the holder. > Oxygen sensor connectors (figure shows cylinders 1 to 4) 

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   Oxygen sensor connectors (figure shows cylinders 1 to 4)

2. Expose oxygen sensor cable -1-  and route it down to the primary catalytic converter.

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   Catalytic converter - naturally aspirated engine

3. Remove heat shield on the cardan joint of the steering column. -arrows- 

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   Heat shield on steering gear

4. Unscrew two coolant pipe screws on the converter bell housing -arrow-  . Loosen the coolant pipe.

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   Coolant pipes on converter bell housing

5. Remove sheetmetal holders for the primary catalytic converter -6, 7, 10-  .
   Fig 1: Holder For Catalytic Converter Components Location - Naturally Aspirated Engine

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   Holder for catalytic converter - naturally aspirated engine

   1	Exhaust manifold, right
   2	Exhaust manifold, left
   3	Seal
   4	Nut
   5	Primary catalytic converter, left
   6	Holder, left
   7	Screw
   8	Holder, right
   9	Primary catalytic converter, right
   10	Bolts between transmission and engine (holder)

   NOTE: Studs and nuts not loosened correctly 

   • Threaded bolts can break off exhaust manifold 

     → Replace damaged exhaust manifold.

     → Clean the studs and nuts on the exhaust manifold before loosening them and spray with anti-rust agent.

     → Loosen nuts carefully. Loosen the nuts by carefully turning them in both directions if they are very stiff.

     → Heat the threaded joint if necessary.

6. Carefully loosen the flange nuts using a change-over ratchet and several extensions. -2-  > Flange bolts securing primary catalytic converter to exhaust manifold 

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   Catalytic converter on naturally aspirated engine (figure shows cylinders 5 to 8)

   Fig 2: Flange Bolts Tightening Sequence

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   Flange bolts securing primary catalytic converter to exhaust manifold

   1 to 5

   Tightening sequence for nuts

   NOTE: Projecting ceramic catalytic converter 

   • Risk of damage to ceramic catalytic converter 

     → Ensure that your work area is well illuminated.

     → Carefully guide the projecting ceramic catalytic converter past the studs on the exhaust manifold.

     → Cover and store the ceramic monolith for the primary catalytic converter in a safe place until you are ready to install it.

     Protect the ceramic monolith from damage while you are working on the primary catalytic converter. If

     → there are deep cracks or large chips, replace the primary catalytic converter. Slight superficial damage will not impair its function.

7. Carefully remove the primary catalytic converter with the help of another worker.

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   Ceramic monolith and installation position

   1	Primary catalytic converter
   2	Ceramic monolith
   3	Exhaust manifold
   4	Seal
   5	Studs in exhaust manifold

8. Remove sheetmetal seal -4-  . Clean sealing surfaces.

Information 

• Spray all fastening nuts on primary catalytic converter with penetrating oil and allow to work in.

Information 

• To loosen and tighten fastening nuts on flange of turbocharger, several extensions and joints must be used.
• Good lighting and a mirror make removal and fitting easier at places very difficult to reach.

Fig 1: Holder For Catalytic Converter Components Location - Turbo Engine

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Holder for catalytic converter - turbo engine

1. Disconnect the oxygen sensor connectors for the oxygen sensors on the catalytic converter at the water splash panel (follow cable routing) and unclip the cables from the holders. > Oxygen sensor connectors (figure shows cylinders 1 to 4) 

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   Oxygen sensor connectors (figure shows cylinders 1 to 4)

2. Route the oxygen sensor cables to the catalytic converter. -1- 

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   Catalytic converter on turbo engine (figure shows cylinders 1 to 4)

3. Remove the heat protection shield on the steering gear connection. To do this, loosen the fastening screws. > Fastening screws securing heat shield to steering gear connection 

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   Fastening screws securing heat shield to steering gear connection

4. Screw off side catalytic converter holder at the transmission -3-  .

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   Catalytic converter on naturally aspirated engine (figure shows cylinders 5 to 8)

5. Loosen the five fastening nuts on the turbocharger.

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   Turbocharger fastening nuts

6. Remove primary catalytic converter. To do this, carefully turn and pull the primary catalytic converter. Move the steering if necessary and pull the primary catalytic converter past it.
7. Remove and replace flange gasket.