BMW Cars 1999-06

Alternator

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Diagnosis & Testing



Alternator Output Test


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Fig. Typical charging system output voltage test connections



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Fig. VAT-40 charging system tester. Similar testers are available that perform as well



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Fig. A rear view of the alternator showing the regulator, end cover and full field access hole locations

Most automotive repair facilities purchase specialized test equipment to check a vehicle's charging system. The test equipment is expensive, however it is fast and easy to use and able to pinpoint the cause of the problem. This type of test equipment is a good investment for a repair shop, however an alternator can be checked with the use of a reasonably priced volt-ohm (VOM) meter as discussed in Section 1.

A volt/amp tester such as the VAT-40 or an equivalent, which is equipped with a battery load control (carbon pile rheostat), full field tester and an inductive-type pickup clamp (ammeter probe) can be used to test an alternator's diodes, amperage and voltage output following the directions supplied with the tester.

This information is useful for someone who may take it upon themselves to open up an alternator and replace the defective internal part. Almost all alternators used in today's vehicles have internal voltage regulators. Thus when replacing the alternator the voltage regulator no longer must be purchased separately. Because the voltage regulators have no moving parts and are electronically controlled, the only wear related item found in an alternator would be the brushes. More often than not, the alternator brushes are part of the voltage regulator, so in order to replace the brushes, the voltage regulator must be replaced.

The only drawback is that at times the cost of the voltage regulator/brush assembly may be almost as expensive as the alternator itself. Therefore it makes more sense to replace the alternator assembly rather than just one failed component. One common symptom of a failed voltage regulator/brush assembly is that the battery warning light does not operate when the ignition switch is first turned to the ON position without the engine being started. The battery must be disconnected and the alternator removed to replace the voltage regulator.

To test the voltage output of the alternator, use a VOM meter capable or reading at least 20 Volts DC and proceed as follows:

  1. Before starting the test, make sure the battery is in good condition and is fully charged. Check the conditions of the battery cables.
  2.  
  3. Perform the voltage drop test to ensure clean and tight alternator/battery electrical connections.
  4.  
  5. Be sure the alternator drive belt is properly tensioned, as outlined in Section 1.
  6.  
  7. Set the parking brake, then place the transmission in Park or Neutral.
  8.  
  9. Start the engine and let it run until it reaches normal operating temperature.
  10.  
  11. Connect the VOM meter to the battery following the proper polarity for the leads. Connect the positive lead to the positive terminal of the battery and attach the negative lead of the VOM meter to the negative terminal of the battery or a known good ground on the vehicle.
  12.  


NOTE
On vehicles with a trunk mounted battery, the auxiliary jump connectors can be use in the engine compartment. For details see the jump starting procedures in Section 1.

  1. Raise the engine speed to 1,500 rpm and check the voltage. The voltage should be 13.5-14.2 Volts. If the voltage is not within specification replace the alternator.
  2.  


NOTE
If the voltage exceeds 14.2 Volts the battery could be damaged. Higher than recommended charging system voltages can warp the battery casing, boil the fluid out of the battery, and warp the internal plates. If battery damage has occurred, neutralize the battery mounting area with a 50 / 50 solution of baking soda and water, then replace the battery.

Voltage Drop Test

NOTE
These tests will show the amount of voltage drop across the alternator output wire from the alternator output (B+) terminal to the battery positive post. They will also show the amount of voltage drop from the ground (-) terminal on the alternator.

A voltmeter with a 0-18 volt DC scale should be used for these tests. By repositioning the voltmeter test leads, the point of high resistance (voltage drop) can easily be found. Test points on the alternator can be reached by either removing the air cleaner housing or below by raising the vehicle.

  1. Before starting the test, make sure the battery is in good condition and is fully charged. Check the conditions of the battery cables.
  2.  
  3. Start the engine, let it warm up to normal operating temperatures, then turn the engine OFF .
  4.  
  5. Connect an engine tachometer, following the manufacturer's directions.
  6.  
  7. Make sure the parking brake is fully engaged.
  8.  
  9. Start the engine, then place the blower on HIGH, and turn on the high beam headlamps and interior lamps.
  10.  
  11. Bring the engine speed up to 2,400 rpm and hold it there.
  12.  
  13. To test the ground (-) circuitry, perform the following:
    1. Touch the negative lead of the voltmeter directly to the positive battery terminal.
    2.  
    3. Touch the positive lead of the voltmeter to the B+ output terminal stud on the alternator (NOT the terminal mounting nut). The voltage should be no higher than 0.6 volts. If the voltage is higher than 0.6 volts, touch the test lead to the terminal mounting stud nut, and then to the wiring connector. If the voltage is now below 0.6 volts, look for dirty, loose or poor connections at this point. A voltage drop test may be performed at each ground (-) connection in the circuit to locate the excessive resistance.
    4.  

  14.  
  15. To test the positive (+) circuitry, perform the following:
    1. Touch the positive lead of the voltmeter directly to the negative battery terminal.
    2.  
    3. Touch the negative lead of the voltmeter to the ground terminal stud on the alternator case (NOT the terminal mounting nut). The voltage should be no higher than 0.3 volts. If the voltage is higher than 0.3 volts, touch the test lead to the terminal mounting stud nut, and then to the wiring connector. If the voltage is now below 0.3 volts, look for dirty, loose or poor connections at this point. A voltage drop test may be performed at each positive (+) connection in the circuit to locate the excessive resistance.
    4.  

  16.  
  17. This test can also be performed between the alternator case and the engine. If the test voltage is higher than 0.3 volts, check for corrosion at the alternator mounting points or loose alternator mounting.
  18.  

Precautions



Several precautions must be observed with alternator equipped vehicles to avoid damage to the unit.



ALWAYS observe proper polarity of the battery connections. Use extreme care when jump starting the car. Reversing the battery connections may cause the battery to explode, or result in damage to the one-way rectifiers.
 
ALWAYS remove the battery or, at least, disconnect the cables while charging to avoid damaging the alternator.
 
ALWAYS match and/or consider the polarity of the battery, alternator and regulator before making any electrical connections within the system.
 
ALWAYS disconnect the battery ground terminal while repairing or replacing any electrical components.
 
NEVER use a fast battery charger to jump start a vehicle with a dead battery.
 
NEVER attempt to polarize an alternator.
 
NEVER use test lights of more than 12 volts when checking diode continuity.
 
NEVER ground or short out the alternator or regulator terminals.
 
NEVER separate the alternator on an open circuit. Make sure all connections within the circuit are clean and tight.
 
NEVER use arc welding equipment on the car with the battery cable, PCM or alternator connected.
 
NEVER operate the alternator with any of its or the battery's lead wires disconnected.
 
NEVER subject the alternator to excessive heat or dampness (for instance, steam cleaning the engine).
 
When utilizing a booster battery as a starting aid, always connect the positive to positive terminals and the negative terminal from the booster battery to a good engine ground on the vehicle being started.
 

Several precautions must be observed with alternator equipped vehicles to avoid damaging the unit. They are as follows:



If the battery is removed for any reason, make sure it is reconnected with the correct polarity. Reversing the battery connections may result in damage to the one-way rectifiers.
 
When utilizing a booster battery as a starting aid, always connect it as follows: positive to positive, and negative (booster battery) to a good ground on the engine.
 
Never use a fast charger as a booster to start vehicles with alternating-current (AC) circuits.
 
When servicing the battery with a fast charger, always disconnect the battery cables.
 
Never attempt to polarize an alternator.
 
Avoid long soldering times when replacing diodes or transistors. Prolonged heat is damaging to alternators.
 
Do not use test lamps of more than 12 volts for checking diode continuity.
 
Do not short across or ground any of the terminals on the alternator.
 
The polarity of the battery, alternator and regulator must be matched and considered before making any electrical connections within the system.
 
Never operate the alternator on an open circuit. Make sure all connections within the circuit are clean and tight.
 
Turn OFF the ignition switch and then disconnect the battery terminals when performing any service on the electrical system or charging the battery.
 
Disconnect the battery ground cable if arc welding is to be done on any part of the vehicle.
 

Removal & Installation



During installation of the alternator, refer to the following information for proper tightening of the fasteners. Alternator fastener torque specifications for all models:



Alternator terminal M6 fasteners: 61 inch lbs. (7 Nm)
 
Alternator terminal M8 fasteners: 115 inch lbs. (13 Nm)
 
Alternator bearing block fasteners: 31 ft. lbs. (43 Nm)
 
Alternator crankcase fasteners (M8 thread): 15 ft. lbs. (21 Nm)
 
Alternator V-belt type pulley nut: 33 ft. lbs. (45 Nm)
 
Alternator ribbed belt pulley nut (with cooling jacket): 59 ft. lbs. (80 Nm)
 
Alternator ribbed belt pulley nut (without cooling jacket): 51 ft. lbs. (70 Nm)
 

During removal and installation of the alternator, refer to the following information for proper tightening of the fasteners.

Alternator fastener torque specifications for all models:



M6 fasteners: 61 inch lbs. (7 Nm)
 
M8 fasteners: 115 inch lbs. (13 Nm)
 
Alternator mounting fasteners: 31 ft. lbs. (43 Nm)
 
Alternator pulley nut (V-belt type): 33 ft. lbs. (45 Nm)
 
Alternator pulley nut (ribbed drive belt type): 51 ft. lbs. (70 Nm)
 

Alternator brush minimum length:



Distance from housing to end of brush: 0.20 inches (5 mm)
 

During installation of the alternator, refer to the following information for proper tightening of the fasteners. Alternator fastener torque specifications for all models:



Alternator terminal M6 fasteners: 61 inch lbs. (7 Nm)
 
Alternator terminal M8 fasteners: 115 inch lbs. (13 Nm)
 
Alternator bearing block fasteners: 31 ft. lbs. (43 Nm)
 
Alternator crankcase fasteners (M8 thread): 15 ft. lbs. (21 Nm)
 
Alternator V-belt type pulley nut: 33 ft. lbs. (45 Nm)
 
Alternator ribbed belt pulley nut (with cooling jacket): 59 ft. lbs. (80 Nm)
 
Alternator ribbed belt pulley nut (without cooling jacket): 51 ft. lbs. (70 Nm)
 

E30 Models

NOTE
When the battery is disconnected the radio code, on-board computer and clock settings will be lost. The radio code should be obtained before disconnecting the battery or radio. Once the battery has been reconnected, the radio will not function unless the code is keyed in.

  1. If needed, read the stored fault memories from the control module.
  2.  
  3. Turn the ignition switch to the OFF position.
  4.  
  5. Disconnect the negative battery cable. Remove the air cleaner assembly.
  6.  
  7. Disconnect the wires from the rear of the alternator, marking them for installation. Note the presence of a ground wire on some vehicles. On the 325i and M3 models, it may be easier to remove the alternator mounting bolts first, then turn it, and remove the wires.
  8.  
  9. If equipped with an alternator cooling duct, loosen the hose clamp on the alternator and remove the cooling duct.
  10.  
  11. Loosen the lock bolt, turn the tensioning bolt to loosen the belt tension and remove the belt. Remove the mounting bolts and remove the alternator.
  12.  

To install:

  1. Install the alternator in position and secure with the retaining bolts.
  2.  
  3. The tensioning bolt on the front of the alternator must be turned so as to tension the belt, using a torque wrench, until the torque is approximately 60 inch lbs. (7 Nm). Then, hold the adjustment nut with one wrench while tightening the locknut at the rear of the unit. Make sure, if the unit has a ground wire on the alternator, it has been reconnected as removed
  4.  
  5. Install the fan and cowl.
  6.  
  7. Install the air cleaner and connect the hoses as necessary.
  8.  
  9. Install the alternator cooling duct, then reconnect the wires to the alternator.
  10.  
  11. The balance of the installation is the reverse of the removal procedure, making sure to re-code the radio as necessary and tighten the alternator fasteners, as follows:

    M6 fasteners: 61 inch lbs. (7 Nm)
     
    M8 fasteners: 115 inch lbs. (13 Nm)
     
    Alternator mounting fasteners: 31 ft. lbs. (43 Nm)
     
    Alternator pulley nut (V-belt type): 33 ft. lbs. (45 Nm)
     
    Alternator pulley nut (ribbed drive belt type): 51 ft. lbs. (70 Nm)
     

  12.  

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Set the ignition switch to the OFF position.
  4.  
  5. Disconnect the negative battery cable. Remove the air cleaner assembly.
  6.  
  7. Disconnect the wires from the rear of the alternator, marking them for installation. Note the presence of a ground wire on some vehicles. On the 325i and M3 models, it may be easier to remove the alternator mounting bolts first, then turn it, and remove the wires.
  8.  
  9. If equipped with an alternator cooling duct, loosen the hose clamp on the alternator and remove the cooling duct.
  10.  
  11. Loosen the lock bolt, turn the tensioning bolt to loosen the belt tension and remove the belt. Remove the mounting bolts and remove the alternator.
  12.  

To install:

  1. Install the alternator in position and install the retaining bolts.
  2.  
  3. The tensioning bolt on the front of the alternator must be turned so as to tension the belt, using a torque wrench, until the torque is approximately 60 inch lbs. (7 Nm). Then, hold the adjustment nut with one wrench while tightening the locknut at the rear of the unit. Make sure, if the unit has a ground wire on the alternator, it has been reconnected as removed
  4.  
  5. Install the fan and cowl.
  6.  
  7. Install the air cleaner and connect the hoses as necessary.
  8.  
  9. Install the alternator cooling duct, then reconnect the wires to the alternator.
  10.  
  11. The balance of the installation is in reverse order of removal.
  12.  

E36 Models
4-Cylinder Engines

NOTE
When the battery is disconnected the radio code, on-board computer and clock settings will be lost. The radio code should be obtained before disconnecting the battery or radio. Once the battery has been reconnected, the radio will not function unless the code is keyed in.

  1. If needed, read the stored fault memories from the control module.
  2.  
  3. Turn the ignition switch to the OFF position.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Rotate the electrical connector at the Mass Air Flow (MAF) sensor counterclockwise and carefully pull the connector off.
  8.  
  9. Remove the intake air filter upper housing complete with the air-flow sensor.
  10.  
  11. On M42 engines:
    1. Loosen the alternator belt adjustment fasteners and remove the drive belt. For specific details, refer to Section 1.
    2.  
    3. Disconnect the alternator-to-body ground strap at the body.
    4.  

  12.  
  13. On M44 engines:
    1. Remove the alternator drive belt. For specific details, refer to Section 1.
    2.  
    3. Remove the upper belt roller to access the upper alternator mounting bolt.
    4.  

  14.  
  15. Remove the wire cover cap and disconnect the wires at the alternator.
  16.  
  17. Remove the alternator mounting bolts and remove the alternator assembly.
  18.  

To install:

  1. Installation is the reverse of the removal procedure making sure to re-code the radio as necessary and tighten the alternator fasteners, as follows:

    M6 fasteners: 61 inch lbs. (7 Nm)
     
    M8 fasteners: 115 inch lbs. (13 Nm)
     
    Alternator mounting fasteners: 31 ft. lbs. (43 Nm)
     
    Alternator pulley nut (V-belt type): 33 ft. lbs. (45 Nm)
     
    Alternator pulley nut (ribbed drive belt type): 51 ft. lbs. (70 Nm)
     

  2.  



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Fig. A top side view of the alternator installed on M42 engines



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Fig. A suitable prytool is used to remove the guide pulley dust cover-M44 engine shown



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Fig. The guide pulley must be removed to access the top alternator mounting bolt



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Fig. Once the guide pulley is removed, the top alternator mounting bolt is easy to access



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Fig. Remove the two alternator mounting bolts and the alternator is ready to remove

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Set the ignition switch to the OFF position.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Rotate the electrical connector at the mass air flow sensor counter clockwise and carefully pull off connector.
  8.  
  9. Remove the intake air filter upper housing complete with the air-flow sensor.
  10.  
  11. On M42 engines:
    1. Loosen the alternator belt adjustment fasteners and remove the drive belt.
    2.  
    3. Disconnect the alternator-to-body ground strap at the body.
    4.  

  12.  
  13. On M44 engines:
    1. Remove the alternator drive belt.
    2.  
    3. Remove the upper belt roller to access the upper alternator mounting bolt.
    4.  

  14.  
  15. Remove the wire cover cap and disconnect the wires at the alternator.
  16.  
  17. Remove the alternator mounting bolts and remove the alternator assembly.
  18.  
  19. Installation is in reverse order of removal making sure to re-code the radio as necessary.

    Click image to see an enlarged view

    Fig. A top side view of the alternator installed on M42 engines

  20.  

6-Cylinder Engines

NOTE
When the battery is disconnected the radio code, on-board computer and clock settings will be lost. The radio code should be obtained before disconnecting the battery or radio. Once the battery has been reconnected, the radio will not function unless the code is keyed in.

  1. If needed, read the stored fault memories from the control module.
  2.  
  3. Turn the ignition switch to the OFF position.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Remove the intake air filter housing as follows:
    1. Rotate the electrical connector at the Mass Air Flow (MAF) sensor counterclockwise and carefully pull the connector off.
    2.  
    3. Loosen the hose clamp at the intake manifold side of the 90° air intake bellows and remove the hose from the throttle plate.
    4.  
    5. Loosen the air filter mounting fasteners at their support brackets.
    6.  
    7. Remove the air filter housing complete with the MAF sensor and the 90° air intake bellows. If necessary, release the clips between the sensor and the air filter housing and remove separately.
    8.  

  8.  


NOTE
The fan clutch assembly has left hand threads! Loosen by turning clockwise.

  1. Remove the radiator cooling fan and fan clutch assembly by supporting the water pump pulley with Tool No. 11 5 030 or its equivalent and loosen the fan clutch by turning it clockwise with Tool No. 11 5 040 or its equivalent.
  2.  
  3. If equipped with air conditioning, and additional space is desired, remove the air conditioner drive belt. For specific details please refer to Section 1.
  4.  
  5. Remove the alternator belt as outlined in Section 1.
  6.  
  7. If equipped, remove the vent hose from the rear of the alternator.
  8.  
  9. Remove the alternator wire terminal protective cap from the back of the alternator.
  10.  
  11. Label and remove the wires from the alternator.
  12.  
  13. If equipped, remove the belt guide roller from the top of the alternator.
  14.  
  15. While supporting the alternator, remove the alternator mounting fasteners, then remove the alternator.
  16.  
  17. Installation is the reverse of the removal procedure making sure to re-code the radio as necessary and tighten the alternator fasteners, as follows:

    M6 fasteners: 61 inch lbs. (7 Nm)
     
    M8 fasteners: 115 inch lbs. (13 Nm)
     
    Alternator mounting fasteners: 31 ft. lbs. (43 Nm)
     
    Alternator pulley nut (V-belt type): 33 ft. lbs. (45 Nm)
     
    Alternator pulley nut (ribbed drive belt type): 51 ft. lbs. (70 Nm)
     

  18.  



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Fig. The engine cooling fan is removed by holding the drive pulley and rotating the fan/fan clutch assembly clockwise



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Fig. When installing the belt idler tensioner roller, make sure the alignment tab is seated into the slot-M50 engine shown

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Set the ignition switch to the OFF position.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Remove the intake air filter housing as follows:
    1. Rotate the electrical connector at the mass air flow sensor counter clockwise and carefully pull off connector.
    2.  
    3. Loosen the hose clamp at the intake manifold side of the 90° air intake bellows and remove the hose from the throttle plate.
    4.  
    5. Loosen the air filter mounting fasteners at their support brackets.
    6.  
    7. Remove the air filter housing complete with the mass air flow sensor and the 90° air intake bellows. If necessary, release the clips between the mass air flow sensor and the air filter housing and remove separately.
      NOTE
      The fan clutch assembly has left hand threads. Loosen by turning clockwise.

    8.  

  8.  
  9. Remove the radiator cooling fan and fan clutch assembly by supporting the water pump pulley by using Tool No. 11 5 030 or its equivalent and loosen the fan clutch by turning it clockwise with Tool No. 11 5 040 or its equivalent.
  10.  
  11. If equipped with air conditioning, and additional space is desired, remove the air conditioner drive belt.
  12.  
  13. Remove the alternator belt.
  14.  
  15. If equipped, remove the vent hose from the rear of the alternator.
  16.  
  17. Remove the alternator wire terminal protective cap from the back of the alternator.
  18.  
  19. Label and remove the wires from the alternator.
  20.  
  21. If equipped, remove the belt guide roller from the top of the alternator.
  22.  
  23. While supporting the alternator, remove the alternator mounting fasteners, then remove the alternator.
  24.  
  25. Installation is in reverse order of removal making sure to re-code the radio as necessary.

    Click image to see an enlarged view

    Fig. The engine cooling fan is removed by holding the drive pulley and rotating the fan/fan clutch assembly clockwise



    Click image to see an enlarged view

    Fig. When installing the belt idler tensioner roller, make sure the alignment tab is seated into the slot-M50 engine shown

  26.  

M50/M52/S50 Engines
  1. Disconnect the battery ground cable.
  2.  
  3. Remove the air cleaner and air mass sensor.
  4.  
  5. Remove the fan and cowl.
  6.  
  7. Loosen the hose clamps on the intake manifold.
  8.  
  9. Unclip the upper section of the filter housing and place to one side.
  10.  
  11. Loosen the hose clamp on the vent hose and remove the vent hose.
  12.  
  13. Remove the covers of the tensioning roller and the reversing roller. Loosen and remove the drive belt.
  14.  
  15. Remove the protective cap. Disconnect the wires from the rear of the alternator, marking them for later installation.
  16.  
  17. Remove the bolts and remove the alternator.
  18.  
  19. If the voltage regulator needs to be replaced unfasten the two cover screws on the back of the alternator and lift out the voltage regulator
  20.  

To install:

  1. If the voltage regulator was removed, clean the contact surfaces and check the contact spring tension. The contacts should extend at least 5 mm from the voltage regulator body. Install the voltage regulator, replace the cover and install the two cover screws.
  2.  
  3. Position the alternator and install the bolts. Tighten the bolts to 2.5 ft. lbs. (3.5 Nm).
  4.  
  5. The tab on the tensioning roller must be engaged in the slot/groove .
  6.  
  7. Connect the wires to the back of the alternator.
  8.  
  9. Route the drive belt and tighten. Replace the covers on the rollers.
  10.  
  11. Install the vent hose and tighten the hose clamp.
  12.  
  13. Position the upper section of the filter housing and clip the fasteners.
  14.  
  15. Tighten the hose clamps on the intake manifold.
  16.  
  17. Install the fan and cowl.
  18.  
  19. Install and connect the air cleaner and air mass sensor.
  20.  
  21. Connect negative battery cable.

    Click image to see an enlarged view

    Fig. Remove the drive belt-M50/M52/S50 engine



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    Fig. Alternator wires-M50/M52/S50 engine



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    Fig. Tensioner tab alignment-M50/M52/S50 engine

  22.  

M54 And S54 Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Suction filter housing
     
    Fan clutch
     
    Alternator drive belt
     
    Power steering pump supply tank, secure aside with hoses attached
     
    Alternator air hose, if equipped
     
    Electrical connectors
     
    Idler pulley, if equipped
     
    Bolts and remove the alternator
     

  4.  
  5. To install, reverse the removal procedure. Torque all fasteners properly. When installing the belt idler tensioner roller, make sure the alignment tab is seated into the slot

    Click image to see an enlarged view

    Fig. Mounting bolt (1) and idler pulley (2) used on some models



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    Fig. Mounting bolt on models without idler pulley



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    Fig. When installing the belt idler tensioner roller, make sure the alignment tab is seated into the slot

  6.  

M60/M62 Engines
  1. Disconnect the battery ground cable.
  2.  
  3. Remove the holder of the vacuum hoses on the radiator cowl panel.
  4.  
  5. Hold the fan pulley with tool 11 5 030 or equivalent. The tool is designed to be bolted to 2 of the pulley bolts and to provide the resistance to allow the fan to be unscrewed from the pulley.
  6.  
  7. Unscrew the fan bolts clockwise. Remove the fan and keep upright. Be careful of the radiator fins.
  8.  
  9. Remove the fan cowl by disconnecting the left and right clips. Take off upwards.
  10.  
  11. Loosen the drive belt tensioner nuts to slacken the drive belt. Remove the drive belt. Remove the drive belt tensioner nuts and the tensioner pulley bolt. Remove the tensioner.
  12.  
  13. Loosen the oil filter nuts and pull the oil filter forward about 5/32 inch (4mm).
  14.  
  15. Remove the top and side alternator mounting bolts.
  16.  
  17. Lift and safely support the vehicle. Remove the splash guards.
  18.  
  19. Disconnect the vent hose of the alternator at the alternator.
  20.  
  21. Remove the bottom alternator mounting bolt.
  22.  
  23. Pull the alternator forward. Remove the protective cap. Disconnect the wires (B+ and D+) from the rear of the alternator, marking them for later installation.
  24.  
  25. Lower the vehicle.
  26.  
  27. Disengage the radiator at the left and right sides by pushing in with a screwdriver.
  28.  
  29. Protect the radiator with a sheet metal plate to prevent damage while removing the alternator. Unscrew the pulley on the water pump.
  30.  
  31. To remove the alternator: the alternator mounting flange must be turned clockwise out from underneath the oil filter mounting flange. Pull the alternator forward. Remove the alternator upwards.
  32.  
  33. To remove the voltage regulator, remove the two bolts from the rear of the alternator and carefully remove the voltage regulator. Clean the contact surfaces and check the tension of the spring contacts.
  34.  

To install:

  1. Mount the voltage regulator and install the two bolts.
  2.  
  3. Lower and rotate the alternator into position making sure to align the mounting holes.
  4.  
  5. Install the pulley on the water pump and remove the sheet metal protective plate from the radiator. Torque the pulley nut to 40 ft. lbs. (55 Nm).
  6.  
  7. Install the clips on the radiator and squeeze together so that the splines are heard to engage several times.
  8.  
  9. Raise and safely support the vehicle.
  10.  
  11. Connect the wires to the back of the alternator.
  12.  
  13. Install the bottom alternator mounting bolt.
  14.  
  15. Connect the vent hose of the alternator and tighten the hose clamp.
  16.  
  17. Install the splash guards. Lower the vehicle.
  18.  
  19. Install the top and side alternator mounting bolts.
  20.  
  21. Return the oil filter to its original position and tighten the nuts.
  22.  
  23. Route the drive belt. Install the drive belt tensioner and pulley. As shown in illustration, preload the adjusting plate on the hexagon nut (1) up to the end of the slot (2). Tighten the nuts (3).
  24.  
  25. Install the fan cowl by connecting the left and right clips.
  26.  
  27. Install the fan using tool 11 5 040 or equivalent wrench and holding tool 11 5 030 or equivalent. Torque the nut to 29 ft. lbs. (40 Nm). If using the tool set the torque wrench to 22 ft. lbs. (30 Nm). The additional length of the tool multiplies the torque to achieve 29 ft. lbs. (40 Nm) at the nut.
  28.  
  29. Install the holder of the vacuum hoses on the radiator cowl panel.
  30.  
  31. Connect negative battery cable.

    Click image to see an enlarged view

    Fig. Drive belt routing-M60/M62 engines



    Click image to see an enlarged view

    Fig. Drive belt tensioner-M60/M62 engines

  32.  

M62 And S62 Engines
Air Cooled Alternator
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Fasteners from oil filter housing, place housing aside
     
    Electrical connectors
     
    Cooling air guide
     
    Bolts and remove the alternator
     

  4.  
  5. To install, reverse the removal procedure. Torque all fasteners properly.

    Click image to see an enlarged view

    Fig. Alternator mounting bolts on M62/S62 air cooled alternator

  6.  

Liquid Cooled Alternator
  1. Before servicing the vehicle, refer to the Precautions section.
    WARNING
    Be sure to perform this procedure with the engine cool only.

  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Fan impeller and clutch from water pump
     
    Drain coolant
     
    Three bottom bolts from the alternator
     
    Electrical connectors
     
    Fastener from roller and lay aside
     
    Remaining mounting bolts and alternator
     
    Pull alternator towards front and out. Disconnect upper coolant hose if necessary
     

  4.  
  5. To install, reverse the removal procedure. Replace the sealing ring. Torque all fasteners properly.
  6.  

N52 Engines

CAUTION
Aluminum-magnesium material. No steel fasteners may be used due to the threat of electrochemical corrosion. A magnesium crankcase requires aluminum fasteners exclusively. Aluminum fasteners must be replaced each time they are removed. The end faces of aluminum fasteners are painted blue for purposes of identification. Torque specifications and torque angles must be observed for risk of damage.

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Drain coolant
     
    Radiator
     
    Intake filter housing
     
    Alternator drive belt
     
    Electrical connections and slacken nut
     
    Remove bolts and remove alternator
     

  4.  
  5. To install, reverse the removal procedure. Replace all aluminum bolts. Torque all fasteners properly.
  6.  

N62 Engines
  1. Before servicing the vehicle, refer to the Precautions section.
    WARNING
    Be sure to perform this procedure with the engine cool only.

  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Drain coolant
     
    Radiator
     
    Alternator drive belt
     
    A/C compressor drive belt
     
    Antifriction bearings on left and right of stabilizer bar
     
    Stabilizer bar and secure from falling
     
    Holder from lines on power steering pump
     
    Guide pulley
     
    Electrical connections
     
    Mounting bolts and alternator
     

  4.  
  5. To install, reverse the removal procedure. Replace the sealing ring. Torque all fasteners properly.
  6.  

 
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