12 31 020 Removing and installing or replacing alternator (M52, M52TU, S50US, S52, M54, M56)

WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2005 BMW 325xi, 2005 BMW 325i, 2005 BMW 325Ci, 2004 BMW 325xi, and 2004 BMW 325i. However, it is still accessible from the selected car via links, so may be relevant.

Necessary Preliminary Tasks:

Read out stored fault messages.
Switch off ignition.
Follow instructions for disconnecting and connecting battery, refer to 12 00... INSTRUCTIONS FOR DISCONNECTING AND CONNECTING BATTERY .
Disconnect and cover battery negative terminal
Remove suction filter housing, refer to 13 71 000 REMOVE AND INSTALLING INTAKE FILTER HOUSING (M52TU, M54) .
Remove fan clutch, refer to 11 52 020 REMOVING AND INSTALLING/REPLACING FAN CLUTCH (S52 / S54 / M52 / M52TU / M54 / M56) .
Remove alternator drive belt, refer to 11 28 010 REPLACING ALTERNATOR DRIVE BELT (M52 / S52 / M52TU / M54 / M56) .

If necessary, drain supply tank for power steering pump, remove with holder and place to one side.

NOTE: Lines on supply tank for power steering pump remain connected.

If fitted:

Remove air hose.

Fig 1: Removing Air Hose

G03164324

Courtesy of BMW OF NORTH AMERICA, INC.

Version 1

Take off cap on connections.

Disconnect plug connection (1).

Fig 2: Disconnecting Plug Connection

G03164325

Courtesy of BMW OF NORTH AMERICA, INC.

Release nut (2) and disconnect battery positive lead.

Tightening torque, refer to 12 31 1AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES - 325I, CI & XI - E46 .

Version 2

Unlock and detach plug connection (1).

Release nut (2) and disconnect battery positive lead.

Fig 3: Disconnecting Battery Positive Lead

G03164326

Courtesy of BMW OF NORTH AMERICA, INC.

Tightening torque, refer to 12 31 1AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES - 325I, CI & XI - E46 .

Version Without Idler Pulley:

Release alternator screws in succession while simultaneously gripping alternator firmly.

Remove alternator.

Fig 4: Removing Alternator

G03164327

Courtesy of BMW OF NORTH AMERICA, INC.

Version With Idler Pulley:

Remove cover from idler pulley (1).

Fig 5: Removing Cover From Idler Pulley

G03164328

Courtesy of BMW OF NORTH AMERICA, INC.

Release screw and remove idler pulley (1).

Release screw and remove alternator (2).

Version With Idler Pulley:

Installation:

Turning lock of tensioning roller must engage in alternator groove.

Fig 6: Turning Lock Of Tensioning Roller Must Engage In Alternator Groove

G03164329

Courtesy of BMW OF NORTH AMERICA, INC.

Interrogate fault memory of DME control unit.

Now clear the fault memory.