18 32 050 Removing and installing/renewing catalytic converters for cylinders 1-4 (N63O1)

Necessary preliminary tasks: 

• Remove upper HEAT SHIELD .
• Remove the front bulkhead SOUND INSULATION .
• Remove EXHAUST SYSTEM .
• Remove VACUUM PUMP .
• Remove the RIGHT MONITORING SENSOR .

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

Screw (1) is located between the catalytic converters.

Fig 1: Identifying Heat Shields And Screw

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

Fig 2: Identifying Heat Shield Screw (Bottom Right)

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Release the screws (1) on the right heat shield.

Unclip and remove the right heat shield.

Fig 3: Identifying Screws On Right Heat Shield

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

Fig 4: Identifying Heat Shield Screws (Bottom Left)

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Release screw (1) on right left shield.

Unclip and remove the heat shield (2) on the left.

Fig 5: Identifying Screw On Right Left Shield

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Release screws (1).

Tightening torque 18 32 2AZ .

Fig 6: Identifying Screws

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Loosen screws (1) on the catalytic converter cylinders 1-4 on the back of the cylinder head.

Tightening torque 18 32 3AZ .

Fig 7: Identifying Screws On Catalytic Converter Cylinders 1-4

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Loosen screws (1) on the catalytic converter cylinders 1-4 on the back of the cylinder head.

Tightening torque 18 32 3AZ .

Fig 8: Identifying Screws On Catalytic Converter Cylinders 1-4 On Back Of Cylinder Head

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Release screw (1) only.

Tightening torque 18 32 1AZ .

Remove and renew clamp (2) only.

Installation note: 

Clamps must be installed with the screws toward the inside (Figure). Otherwise, a top heat shield can no longer be installed.

Fig 9: Identifying Clamps And Screws

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Remove catalytic converter for cylinders 1-4.

Replace gasket on exhaust turbocharger.

Installation note: 

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

Tightening torque 18 32 1AZ .

Fig 10: Identifying V-Band Clamp Ends

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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 11: 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 12: Identifying Misalignment Of V-Band Clamp Ends

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Assemble engine.

Check exhaust system for leaks.