Removing and installing/replacing cylinder 7-12 catalytic converter (N74)

Necessary preliminary tasks: 

• Remove left INTAKE SILENCER HOUSING
• Remove CHARGE AIR PIPE, cylinders 7-12
• Remove EXHAUST SYSTEM 
• Remove CONTROL SENSOR , cylinders 7 to -12
• Remove MONITORING SENSOR, cylinders 7-12

Unscrew nuts (1).

Remove heat shield (2).

Fig 1: Identifying Heat Shield And Nuts

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Release screws (1).

Tightening torque: see 3AZ in 18 31 EXHAUST SYSTEM

Remove holder (2).

Fig 2: Identifying Holder And Screws

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Release clamp (1).

Tightening torque: see 4AZ in 18 31 EXHAUST SYSTEM

Replace clamp and seal.

Slacken nut (2).

Tightening torque: see 5AZ in 18 31 EXHAUST SYSTEM

Feed out catalytic converter (3) and remove.

Installation: 

To facility assembly, the V-belt clamp can be turned 180°. Make sure that a distance of 20 mm from other components is maintained.

Fig 3: Identifying Catalytic Converter, Clamp And Nut

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Installation: 

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

Tightening torque: see 4AZ in 18 31 EXHAUST SYSTEM

Fig 4: Identifying V-Band Clamps

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Installation: 

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

Tightening torque: see 4AZ in 18 31 EXHAUST SYSTEM

Fig 5: Identifying Gap Between Ends Of V-Band Clamps

Courtesy of BMW OF NORTH AMERICA, INC.

Installation: 

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

Tightening torque: see 4AZ in 18 31 EXHAUST SYSTEM

Fig 6: Positioning Of V-Band Clamps

Courtesy of BMW OF NORTH AMERICA, INC.

Assemble engine.

Check exhaust system for leaks.