18 32 050 Removing and installing/renewing catalytic converter cylinder 5-8 (N63)

Necessary preliminary tasks 

• Remove UPPER HEAT SHIELD
• Remove both monitoring sensors. See REPLACING LEFT MONITOR SENSOR and REPLACING RIGHT MONITOR SENSOR .
• Remove REAR UNDERBODY PROTECTION .

Picture shows the left side, the procedure for the right side is identical.

Release nuts (1) on left and right.

Tightening torque 18 31 1AZ .

Replace self-locking nuts.

Replace gaskets.

Fig 1: Identifying Flange Nuts

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Unscrew nuts (1).

Tightening torque 18 20 1AZ .

Slacken nuts (2).

Lower exhaust system slightly towards the front.

Fig 2: Identifying Bracket Nuts

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Release screws (1).

Remove left cable clip (2).

Fig 3: Identifying Cable Clip And Screws

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Release screw (1) on catalytic converter.

Tightening torque 18 32 4AZ .

Release clamp (2) on catalytic converter.

Replace clamp (2).

Tightening torque 18 32 1AZ .

Installation note: 

The clamp (2) must be installed with the screw toward the inside (illustration).

Otherwise, the heat shield can no longer be installed on top.

Fig 4: Identifying Heat Shield, Screws And Clamps

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Installation note: 

The ends of the V-band clamps must rest parallel to each other.

Tightening torque 18 32 1AZ .

Fig 5: Identifying Ends Of V-Band Clamps

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Installation note: 

If you can see a gap between the ends of the V-band clamps, release and then repeat the screw connection.

Tightening torque 18 32 1AZ .

Fig 6: Identifying Gap Between Ends Of V-Band Clamps

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Installation note: 

If the ends of the V-band clamps are positioned under each other, release and then repeat the screw connection.

Tightening torque 18 32 1AZ .

Fig 7: Identifying Misalignment Of V-Band Clamp Ends

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Release screw (1) from heat shields (2) and (3).

Screw (1) is located between the catalytic converters.

Fig 8: Identifying Heat Shields And Screw

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Release screws (1) on left heat shield.

Unclip left heat shield and remove.

Fig 9: Identifying Screws On Left Heat Shield

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Release screw (1) on right heat shield.

Fig 10: Identifying Screw On Right Heat Shield

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Release screw (1) on heat shield at bottom right.

Unclip heat shield and remove.

Fig 11: Identifying Screw On Heat Shield At Bottom Right

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Release screws (1).

Detach hose (2) from cylinder head cover.

Release screws (3) on holder.

Tightening torque 18 32 2AZ .

Fig 12: Identifying Cylinder Head Cover Hose And Screws

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Release screws (1) on catalytic converter, cylinders 5-8, rear, at cylinder head.

Tightening torque 18 32 3AZ .

Remove catalytic converter for cylinders 5-8.

Fig 13: Identifying Screws On Catalytic Converter, Cylinders 5-8

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Installation note: 

Picture shows the engine removed.

Replace gasket (1) on left exhaust turbocharger.

Fig 14: Identifying Turbocharger Gaskets

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Installation note: 

Clean sealing surfaces.

Replace gasket (1).

Fig 15: Identifying Gasket

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Assemble engine.

Check exhaust system for leaks.