12 31... Replacing alternator belt pulley

Special tools required: 

• 12 7 121
• 12 7 122
• 12 7 123

Necessary preliminary tasks: 

• Remove drive belt.

Procedure with special tool 12 7 121. 

Illustration shows N42:

If fitted, remove protective cap from belt pulley.

Depending on the alternator version, hold down alternator axis with:

• Torx key
• Hold inner multi-wrench tool (special tool 12 7 122).
  Fig 1: Removing Protective Cap From Belt Pulley

  Courtesy of BMW OF NORTH AMERICA, INC.

Release freewheel with special tool 12 7 121 and remove.

Installation note: 

Tightening torque: 12 31 8AZ .

Procedure with special tool 12 7 123. 

Depending on the alternator version, hold down alternator axis with:

• Torx key
• Hold inner multi-wrench tool (special tool 12 7 122).

Release freewheel with special tool 12 7 123 and a ring spanner and remove.

Installation note: 

Tightening torque: 12 31 8AZ .