Necessary preliminary work

• Remove ACOUSTIC COVER
• REMOVE BOTH INTAKE SILENCER HOUSINGS .
• Remove EXHAUST SYSTEM  .
• Remove both control sensors. See REPLACING LEFT CONTROL SENSOR (N63) and REPLACING RIGHT CONTROL SENSOR (N63) .
• Remove both monitoring sensors. See REPLACING LEFT MONITOR SENSOR (N63) and REPLACING RIGHT MONITOR SENSOR (N63) .

Picture shows the left side, carry out the operation for the right side in an identical way.

Release screws (1).

Remove cable clips on left and right.

Fig 1: Identifying Cable Clips On Left And Right With Screws

Courtesy of BMW OF NORTH AMERICA, INC.

Remove rubber mounts (1) and release screws underneath.

Tightening torque 13 71 5AZ .

Remove cable clip (2).

Remove the HEAT SHIELD (3) at top.

Fig 2: Identifying Rubber Mounts, Cable Clip And Heat Shield At Top

Courtesy of BMW OF NORTH AMERICA, INC.

Remove heat shield (1) at rear left and right.

This is described further below in the instructions.

Release screws (2) on catalytic converter.

Tightening torque 18 32 4AZ .

Loosen the clamps (3) from the catalytic converter.

Replace clamps (3).

Tightening torque 18 32 1AZ .

Installation note: 

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

Fig 3: Identifying Heat Shield At Rear Left And Right, Clamps And Screws On Catalytic Converter

Courtesy of BMW OF NORTH AMERICA, INC.

Installation note: 

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

Tightening torque 18 32 1AZ .

Fig 4: Identifying V-Band Clamps

Courtesy of BMW OF NORTH AMERICA, INC.

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 5: Locating V - Band Clamps Gap

Courtesy of BMW OF NORTH AMERICA, INC.

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 6: Locating V - Band Clamps Position

Courtesy of BMW OF NORTH AMERICA, INC.

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

Screw (1) is located between the catalytic converters.

Fig 7: Identifying Screws On Heat Shields And Catalytic Converters

Courtesy of BMW OF NORTH AMERICA, INC.

Release screws (1) on left heat shield.

Unclip left heat shield and remove.

Fig 8: Identifying Screws On Left Heat Shields

Courtesy of BMW OF NORTH AMERICA, INC.

Release screw (1) on right heat shield.

Fig 9: Identifying Screws On Right Heat Shields

Courtesy of BMW OF NORTH AMERICA, INC.

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

Unclip heat shield and remove.

Fig 10: Identifying Screw On Heat Shields At Bottom Right

Courtesy of BMW OF NORTH AMERICA, INC.

Picture shows the left side, carry out the operation for the right side in an identical way.

Release screws (1).

Detach hose (2) from cylinder head cover.

Release screws (3) on holder.

Tightening torque 18 32 2AZ .

Fig 11: Identifying Hose On Cylinder Head Cover And Screws On Holder

Courtesy of BMW OF NORTH AMERICA, INC.

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

Tightening torque 18 32 3AZ .

Fig 12: Identifying Screws On Catalytic Converter Cylinders 1-4 On Back Of Cylinder Head

Courtesy of BMW OF NORTH AMERICA, INC.

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

Tightening torque 18 32 3AZ .

Fig 13: Identifying Screws On Catalytic Converter, Cylinders 5--8, Rear, At Cylinder Head

Courtesy of BMW OF NORTH AMERICA, INC.

1. Remove catalytic converter for cylinders 5 - 8 (1).
2. Remove catalytic converter for cylinders 1 - 4 (2).
   Fig 14: Identifying Catalytic Converter For Cylinders 5-- 8 And Cylinders 1-- 4

   Courtesy of BMW OF NORTH AMERICA, INC.

Installation note: 

Picture shows the engine removed.

Replace the seals (1) on the exhaust turbocharger.

Fig 15: Identifying Seals On Exhaust Turbocharger

Courtesy of BMW OF NORTH AMERICA, INC.

Installation note: 

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

Clean sealing surfaces.

Replace gasket (1).

Fig 16: Identifying Gasket

Courtesy of BMW OF NORTH AMERICA, INC.

Assemble engine.

Check exhaust system for leak tightness.