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Home >> BMW >> 2008 >> 323i Automatic >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Engine Electrical System - Repair - E90/E91, Z4 >> 31 Alternator with drive >> 12 31 020 Removing and installing or replacing alternator (N52, N52K, N51, N53)

12 31 020 Removing and installing or replacing alternator (N52, N52K, N51, N53)

IMPORTANT: Aluminium-magnesium materials.

No steel screws/bolts may be used due to the threat of electrochemical corrosion.

A magnesium crankcase requires aluminium screws/bolts exclusively.

Aluminium screws/bolts must be replaced each time they are released. 

The end faces of aluminium screws/bolts are painted blue for the purposes of reliable identification.

Jointing torque and angle of rotation must be observed without fail (risk of damage). 

Necessary preliminary tasks: 

Unlock plug (1) and remove.

Slacken nut (2).

Installation: 

For tightening torque refer to 12 31 1AZ in ALTERNATOR WITH DRIVE .

Release screws and remove alternator (3).

Installation: 

Replace aluminium screws. 

For tightening torque refer to 12 31 2AZ in ALTERNATOR WITH DRIVE .

Fig 1: Identifying Alternator, Mounting Screws, Plug And Nut
G04725686Courtesy of BMW OF NORTH AMERICA, INC.