How does alternator works on BMW 325?

The alternator,also known as charging system.

Description & Operation

The charging system is a 12 volt Direct Current (DC) negative (-) ground system. The system consists of an alternator with an internal voltage regulator, an alternator belt, a charging system light, and a battery.

The alternator is mounted onto the engine and the alternator rotor is supported by two sealed bearings within the alternator housing. One end of the alternator rotor has two electrical contacts called slip rings, and the other end of the rotor's shaft protrudes through the alternator housing and has a pulley attached to it. The rotor shaft's pulley is belt-driven by another pulley that is attached to the engine's crankshaft.

The slip rings are electrical contacts that allow voltage to be supplied to the rotor's electrical windings while it spins. The voltage is supplied to the two slip rings via a pair of spring loaded brushes. The brushes are soft enough to not damage the slip rings, yet are made of a material that will conduct an electrical current. The rotor has an electrical winding that is surrounded by a series of metal fingers.

The initial voltage is supplied to the rotor from the battery and is called the excitation current. This electrical current is used to energize the field to begin the generation of electricity. When the electrical current is supplied to the rotor field winding via the slip rings, the rotor becomes an electromagnet. The rotor is surrounded by a series of small electrical coils called the stator assembly. When the rotor spins, the magnetic field from the rotor is absorbed by the electrical coils of the stator assembly. This generates a series of positive and negative electrical pulses in the coils of the stator assembly creating an Alternating Current (AC) and AC voltage.

Because the vehicle's battery, electrical system and the electrical accessories are DC voltage, the AC voltage must be converted to DC voltage. The alternating current from the stator assembly is channeled through a series of diodes that are grouped together to form a component known as the rectifier. A diode is essentially a one way valve, and designed to allow current to pass in only one direction. The collection of diodes that form the rectifier assembly allows the current to flow in one direction, changing the electrical pulses from alternating current (AC voltage) to direct current (DC voltage). Once the alternator rotor begins to rotate and starts to generate electricity, the excitation current comes from its own output, rather than from the battery, although the battery remains as part of the electrical circuit.

Because the electrical needs of the vehicle change depending on operating conditions, the alternator's output needs to be regulated. To accomplish this, a voltage regulator is used to control the alternator's output. To do this, the regulator controls the voltage to the alternator rotor, which regulates the alternator's output by controlling the strength of the magnetic field. The more voltage the rotor receives, the stronger the magnetic field, and the more electrical current the alternator provides. Conversely, the less voltage the rotor receives, the weaker the magnetic field, and the less electrical current the alternator provides.

The alternator is used to maintain the charge of the battery and to power the components of the electrical system. When the ignition key is turned ON , current flows from the battery, through the charging system indicator light on the instrument panel, and to the voltage regulator in the alternator. When the alternator rotor is not moving, the alternator is not producing an electrical current, and the alternator warning light remains on. When the engine is started, the alternator rotor begins to rotate. As the alternator rotor rotates, the alternator generates an electrical current and turns the alternator light off.

When the engine is running, the alternator produces an electrical current that is used to replenish the battery, which is drained slightly during start-up, and to power the electrical components of the vehicle.

Typical alternator component failures include:

Worn brushes

Failed diode(s)

A failed voltage regulator

Symptoms of worn brushes include:

Insufficient voltage output

Loss of electrical power while driving

Symptoms of a failed diode include:

Insufficient amperage output

Battery loses charge when not driving

Symptoms of a failed voltage regulator include:

Insufficient voltage output

Loss of electrical power while driving

Excessive voltage output

Battery fluid loss

Battery overheating

Warped battery casings

This above mentioned details will help you.

Thanks.

For more car related problem troubleshooting:---

This are the sections, you can go through and click the link to read its troubleshooting.

---------

The car will not start?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-start.html

-----------------

Car will not crank?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-crank.html

-----------

Car has no spark?

http://schematicsdiagram.blogspot.com/2011/06/car-has-no-spark.html

-------------

How to troubleshoot car battery?

http://schematicsdiagram.blogspot.com/2011/06/how-to-troubleshoot-car-battery.html

-----------------

How to test starter solenoid?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-starter-solenoid.html

--------------------

How to test cars starter?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-cars-starter.html

How to replace starter in car?

http://schematicsdiagram.blogspot.com/2011/06/how-to-replace-starter-in-car.html

-----------

car will turn over but will not start?

http://technoanswers.blogspot.com/2011/05/car-will-turn-over-but-will-not-start.html

-----------------

Car wont start?

http://howtobyme.blogspot.com/2011/10/car-wont-start.html

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Alternator testing,inspection and removal on 2005 BMW 325?

Alternator

The alternator is the component/part that charge the battery,when vehicle is running.

If its faulty, then vehicle will not charge.

Diagnosis & Testing

Alternator Output Test

Fig. Typical charging system output voltage test connections

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

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. Perform the voltage drop test to ensure clean and tight alternator/battery electrical connections.
3. Be sure the alternator drive belt is properly tensioned, as outlined in Section 1.
4. Set the parking brake, then place the transmission in Park or Neutral.
5. Start the engine and let it run until it reaches normal operating temperature.
6. 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.

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.

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. Start the engine, let it warm up to normal operating temperatures, then turn the engine OFF .
3. Connect an engine tachometer, following the manufacturer's directions.
4. Make sure the parking brake is fully engaged.
5. Start the engine, then place the blower on HIGH, and turn on the high beam headlamps and interior lamps.
6. Bring the engine speed up to 2,400 rpm and hold it there.
7. To test the ground (-) circuitry, perform the following:
   1. Touch the negative lead of the voltmeter directly to the positive battery terminal.
   2. 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.
8. To test the positive (+) circuitry, perform the following:
   1. Touch the positive lead of the voltmeter directly to the negative battery terminal.
   2. 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.
9. 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.

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. Turn the ignition switch to the OFF position.
3. Disconnect the negative battery cable. Remove the air cleaner assembly.
4. 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.
5. If equipped with an alternator cooling duct, loosen the hose clamp on the alternator and remove the cooling duct.
6. 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.

To install:

1. Install the alternator in position and secure with the retaining bolts.
2. 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
3. Install the fan and cowl.
4. Install the air cleaner and connect the hoses as necessary.
5. Install the alternator cooling duct, then reconnect the wires to the alternator.
6. 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)

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Set the ignition switch to the OFF position.
3. Disconnect the negative battery cable. Remove the air cleaner assembly.
4. 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.
5. If equipped with an alternator cooling duct, loosen the hose clamp on the alternator and remove the cooling duct.
6. 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.

To install:

1. Install the alternator in position and install the retaining bolts.
2. 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
3. Install the fan and cowl.
4. Install the air cleaner and connect the hoses as necessary.
5. Install the alternator cooling duct, then reconnect the wires to the alternator.
6. The balance of the installation is in reverse order of removal.

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. Turn the ignition switch to the OFF position.
3. Disconnect the negative battery cable.
4. Rotate the electrical connector at the Mass Air Flow (MAF) sensor counterclockwise and carefully pull the connector off.
5. Remove the intake air filter upper housing complete with the air-flow sensor.
6. On M42 engines:
   1. Loosen the alternator belt adjustment fasteners and remove the drive belt. For specific details, refer to Section 1.
   2. Disconnect the alternator-to-body ground strap at the body.
7. On M44 engines:
   1. Remove the alternator drive belt. For specific details, refer to Section 1.
   2. Remove the upper belt roller to access the upper alternator mounting bolt.
8. Remove the wire cover cap and disconnect the wires at the alternator.
9. Remove the alternator mounting bolts and remove the alternator assembly.

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)

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

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

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

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

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. Set the ignition switch to the OFF position.
3. Disconnect the negative battery cable.
4. Rotate the electrical connector at the mass air flow sensor counter clockwise and carefully pull off connector.
5. Remove the intake air filter upper housing complete with the air-flow sensor.
6. On M42 engines:
   1. Loosen the alternator belt adjustment fasteners and remove the drive belt.
   2. Disconnect the alternator-to-body ground strap at the body.
7. On M44 engines:
   1. Remove the alternator drive belt.
   2. Remove the upper belt roller to access the upper alternator mounting bolt.
8. Remove the wire cover cap and disconnect the wires at the alternator.
9. Remove the alternator mounting bolts and remove the alternator assembly.
10. Installation is in reverse order of removal making sure to re-code the radio as necessary.
    
    
    

    

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

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. Turn the ignition switch to the OFF position.
3. Disconnect the negative battery cable.
4. 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. Loosen the hose clamp at the intake manifold side of the 90° air intake bellows and remove the hose from the throttle plate.
   3. Loosen the air filter mounting fasteners at their support brackets.
   4. 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.

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. If equipped with air conditioning, and additional space is desired, remove the air conditioner drive belt. For specific details please refer to Section 1.
3. Remove the alternator belt as outlined in Section 1.
4. If equipped, remove the vent hose from the rear of the alternator.
5. Remove the alternator wire terminal protective cap from the back of the alternator.
6. Label and remove the wires from the alternator.
7. If equipped, remove the belt guide roller from the top of the alternator.
8. While supporting the alternator, remove the alternator mounting fasteners, then remove the alternator.
9. 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)

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

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. Set the ignition switch to the OFF position.
3. Disconnect the negative battery cable.
4. 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. Loosen the hose clamp at the intake manifold side of the 90° air intake bellows and remove the hose from the throttle plate.
   3. Loosen the air filter mounting fasteners at their support brackets.
   4. 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.
5. 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.
6. If equipped with air conditioning, and additional space is desired, remove the air conditioner drive belt.
7. Remove the alternator belt.
8. If equipped, remove the vent hose from the rear of the alternator.
9. Remove the alternator wire terminal protective cap from the back of the alternator.
10. Label and remove the wires from the alternator.
11. If equipped, remove the belt guide roller from the top of the alternator.
12. While supporting the alternator, remove the alternator mounting fasteners, then remove the alternator.
13. Installation is in reverse order of removal making sure to re-code the radio as necessary.
    
    
    

    

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

    

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

M50/M52/S50 Engines

1. Disconnect the battery ground cable.
2. Remove the air cleaner and air mass sensor.
3. Remove the fan and cowl.
4. Loosen the hose clamps on the intake manifold.
5. Unclip the upper section of the filter housing and place to one side.
6. Loosen the hose clamp on the vent hose and remove the vent hose.
7. Remove the covers of the tensioning roller and the reversing roller. Loosen and remove the drive belt.
8. Remove the protective cap. Disconnect the wires from the rear of the alternator, marking them for later installation.
9. Remove the bolts and remove the alternator.
10. 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

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. Position the alternator and install the bolts. Tighten the bolts to 2.5 ft. lbs. (3.5 Nm).
3. The tab on the tensioning roller must be engaged in the slot/groove .
4. Connect the wires to the back of the alternator.
5. Route the drive belt and tighten. Replace the covers on the rollers.
6. Install the vent hose and tighten the hose clamp.
7. Position the upper section of the filter housing and clip the fasteners.
8. Tighten the hose clamps on the intake manifold.
9. Install the fan and cowl.
10. Install and connect the air cleaner and air mass sensor.
11. Connect negative battery cable.
    
    
    

    

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

    

    Fig. Alternator wires-M50/M52/S50 engine
    
    
    
    

    

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

M54 And S54 Engines

1. Before servicing the vehicle, refer to the Precautions section.
2. 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
3. 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
   
   
   

   

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

   

   Fig. Mounting bolt on models without idler pulley
   
   
   
   

   

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

M60/M62 Engines

1. Disconnect the battery ground cable.
2. Remove the holder of the vacuum hoses on the radiator cowl panel.
3. 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.
4. Unscrew the fan bolts clockwise. Remove the fan and keep upright. Be careful of the radiator fins.
5. Remove the fan cowl by disconnecting the left and right clips. Take off upwards.
6. 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.
7. Loosen the oil filter nuts and pull the oil filter forward about 5/32 inch (4mm).
8. Remove the top and side alternator mounting bolts.
9. Lift and safely support the vehicle. Remove the splash guards.
10. Disconnect the vent hose of the alternator at the alternator.
11. Remove the bottom alternator mounting bolt.
12. 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.
13. Lower the vehicle.
14. Disengage the radiator at the left and right sides by pushing in with a screwdriver.
15. Protect the radiator with a sheet metal plate to prevent damage while removing the alternator. Unscrew the pulley on the water pump.
16. 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.
17. 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.

To install:

1. Mount the voltage regulator and install the two bolts.
2. Lower and rotate the alternator into position making sure to align the mounting holes.
3. 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).
4. Install the clips on the radiator and squeeze together so that the splines are heard to engage several times.
5. Raise and safely support the vehicle.
6. Connect the wires to the back of the alternator.
7. Install the bottom alternator mounting bolt.
8. Connect the vent hose of the alternator and tighten the hose clamp.
9. Install the splash guards. Lower the vehicle.
10. Install the top and side alternator mounting bolts.
11. Return the oil filter to its original position and tighten the nuts.
12. 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).
13. Install the fan cowl by connecting the left and right clips.
14. 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.
15. Install the holder of the vacuum hoses on the radiator cowl panel.
16. Connect negative battery cable.
    
    
    

    

    Fig. Drive belt routing-M60/M62 engines
    
    
    
    

    

    Fig. Drive belt tensioner-M60/M62 engines

M62 And S62 Engines
Air Cooled Alternator

1. Before servicing the vehicle, refer to the Precautions section.
2. 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
3. To install, reverse the removal procedure. Torque all fasteners properly.
   
   
   

   

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

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. 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
3. To install, reverse the removal procedure. Replace the sealing ring. Torque all fasteners properly.

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. 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
3. To install, reverse the removal procedure. Replace all aluminum bolts. Torque all fasteners properly.

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. 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
3. To install, reverse the removal procedure. Replace the sealing ring. Torque all fasteners properly.

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For more car related problem troubleshooting:---

This are the sections, you can go through and click the link to read its troubleshooting.

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The car will not start?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-start.html

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Car will not crank?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-crank.html

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Car has no spark?

http://schematicsdiagram.blogspot.com/2011/06/car-has-no-spark.html

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How to troubleshoot car battery?

http://schematicsdiagram.blogspot.com/2011/06/how-to-troubleshoot-car-battery.html

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How to test starter solenoid?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-starter-solenoid.html

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How to test cars starter?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-cars-starter.html

How to replace starter in car?

http://schematicsdiagram.blogspot.com/2011/06/how-to-replace-starter-in-car.html

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car will turn over but will not start?

http://technoanswers.blogspot.com/2011/05/car-will-turn-over-but-will-not-start.html

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Car wont start?

http://howtobyme.blogspot.com/2011/10/car-wont-start.html

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