Sunday, May 1, 2011

how to replace starter on 2003 bmw 525?

Description & Operation


The battery and starter motor are linked by very heavy gauge electrical cables designed to minimize resistance to the flow of current. Generally, the major power supply cable that leaves the battery goes directly to the starter, while other electrical system needs are supplied by a smaller gauge cable. During starter operation, the positive (+) battery power flows from the battery to the starter solenoid, and the starter is grounded through the engine which is grounded by the battery's negative ground strap.

The starter is a specially designed, direct current electric motor capable of producing a great amount of power for its size. What allows the motor to produce a great deal of power is its tremendous rotating speed. It drives the engine through a tiny pinion gear (attached to the starter's armature), that drives the very large flywheel ring gear at a greatly reduced speed. Another factor allowing it to produce so much power is that only intermittent operation is required of it. Thus, little allowance for air circulation is necessary, and the windings can be built into a very small space.

The starter solenoid is an electromagnetic device that is triggered by the small current supplied by the start circuit of the ignition switch. This electromagnetic action moves a plunger that mechanically engages the starter gear and closes the high amperage switch connecting the starter to the battery. The starting switch circuit is part of the ignition switch. The starting circuit wiring includes a safety circuit, such as a neutral safety switch, or clutch pedal switch, that prevents the engine from being started with the transmission engaged. Also included in the starting circuit is the wiring necessary to connect these in series with the starter solenoid.

The pinion, a small gear, is mounted to a one-way drive clutch. This clutch is splined to the starter armature shaft. When the ignition switch is moved to theSTART position, the solenoid plunger slides the pinion toward the flywheel ring gear via a collar and spring. If the teeth on the pinion and flywheel match properly, the pinion will engage the flywheel immediately. If the gear teeth butt one another, the spring will be compressed and will force the gears to mesh as soon as the starter turns far enough to allow them to do so. As the solenoid plunger reaches the end of its travel, it closes the contacts that connect the battery to the starter, and then the engine is cranked.

As soon as the engine starts, the flywheel ring gear begins turning fast enough to drive the pinion at an extremely high rate of speed. At this point, the one-way clutch begins allowing the pinion to spin faster than the starter shaft so that the starter will not operate at excessive speed. When the ignition switch is released from the start position, the solenoid is de-energized, and a spring pulls the gear out of mesh, interrupting the current flow to the starter.

Some starters employ a separate relay, mounted away from the starter, to switch the motor and solenoid current on and off. The relay replaces the solenoid electrical switch, but does not eliminate the need for a solenoid mounted on the starter used to mechanically engage the starter drive gears. The relay is used to reduce the amount of current the start position of the ignition switch must carry.


WARNING
Never compromise personal safety when working with a vehicle's electrical system.

The starter motor assembly consists of two basic components, the starter motor and the starter relay. Some manufacturers prefer to separate the relay from the starter motor, others prefer to combine the two into one unit. The Bosch® starter motor found on BMW models is a combined unit. The relay used on these starter motor assemblies actually serves two purposes. The relay is used to:



Act as a switch to complete a high amperage electrical circuit between the battery and the starter motor.
Engage the starter motor pinion gear with the flywheel ring gear.

The two most common symptoms of a combination starter motor failure are:



Nothing happens when the ignition key is turned to START .
A clicking noise is heard when the ignition key is turned to START .

  1. Assuming the battery is fully charged and all of the battery cables are properly attached and their connections clean, if nothing happens when the key is turned to START most likely the starter motor solenoid has failed. In an emergency situation a remote starter switch could override the relay and allow the starter to function temporarily.
  2. If a clicking noise is heard, that's an indication that the solenoid is engaging, but the electric motor portion of the starter motor has failed. In an emergency situation, sometimes the starter motor can be rapped sharply with a screwdriver or hammer handle which may startle the starter motor enough to function temporarily.

If the starter motor operation is intermittent, check the operation of the ignition switch. If your starter motor is acting up, use the following steps to troubleshoot the cause and replace the starter motor as necessary. A starter motor replacement is much easier to do in an evening after work or on a day off. It's not something you'll want to be doing on the side of the road.




Solenoid or Relay


Usually the starter and solenoid are replaced as an assembly. Finding a replacement solenoid is not as easy as finding a complete new or rebuilt starter. It's very possible the cost of the solenoid could be equal to the cost of a rebuilt starter motor. If the solenoid is worn, chances are that the starter motor has an equivalent amount of wear. Replacing both as an assembly reduces the chance of having problems with the starter motor soon after replacing the solenoid.

To replace the solenoid:

  1. Remove the starter motor.
  2. Disconnect the copper braid lead from the solenoid terminal. Be careful not to twist and pull on the lead as the nut is removed.
  3. Remove the 2 or 3 screws at the nose end of the solenoid. A hand impact and Phillips bit may be necessary.
  4. Remove the solenoid. Use care to not lose the spring in the solenoid.

To install:

  1. Install the solenoid onto the body of the starter. Coat the threads of the screws with a suitable thread-locking compound and tighten.
  2. Connect the copper braid lead to the solenoid terminal. Be careful not to twist or pull on the lead as the nut is tightened.
  3. Install the solenoid and reinstall the starter motor assembly.

Testing



Starter Solenoid
Bench Test
  1. Note the radio security code and the radio presets.
  2. Disconnect the battery negative cable then the positive cable.
  3. Remove the starter from the vehicle.
  4. Disconnect the field coil wire from the field coil terminal.
  5. Check for continuity between the solenoid terminal and field coil terminal with a continuity tester. Continuity (resistance) should be present.
  6. Check for continuity between the solenoid terminal and solenoid housing. Continuity should be detected. If continuity is detected, the solenoid is good.
  7. If continuity is not detected in either test, the solenoid has an open circuit, is defective, and must be replaced.

On Vehicle Test
  1. Before testing, assure the parking brake is set, the transmission is in Park (automatic) or Neutral (manual), and the battery is fully charged and in good condition.
  2. Connect a voltmeter from the small terminal (terminal 50) on the solenoid to ground. Turn the ignition switch to the START position and test for battery voltage. If battery voltage is not found, inspect the ignition switch circuit. If battery voltage is found, proceed to next step.
  3. Connect an ohmmeter between the battery negative post and the starter housing. The ohmmeter should read zero (0). If not, repair the faulty ground.
  4. If both tests are performed and the solenoid still does not energize, replace the solenoid.

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

Removal & Installation



The starter motor on some models is very difficult to see from the top of engine compartment as it is covered by the intake manifold. On these models, without removing the intake manifold, the starter motor must be removed from underneath the vehicle. Because the starter motor mounting bolts are not easy to access, a long extension with a universal joint mounted on a proper sized socket could be used. A three foot transmission extension is commercially available from tool vendors that has a 3 / 8 inch drive of the driven end and 1 / 2 inch drive on the drive end. If used with a non-binding impact universal joint and a proper fitting impact socket, the starter motor fasteners can be removed from underneath the vehicle.

Once the starter motor fasteners are removed, the starter motor may have to be moved side-to-side several times to loosen the dowel pin if it has corroded in place.


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.

Starter motor electrical terminal fastener torque specifications for all models:



M5 terminal fasteners: 44 inch lbs. (5 Nm)
M6 terminal fasteners: 53 inch lbs. (6 Nm)
M8 terminal fasteners: 115 inch lbs. (13 Nm)

Starter motor mounting fasteners:



Hex head bolts: 36 ft. lbs. (49 Nm)
Torx bolts: 32 ft. lbs. (43 Nm)

Starter motor electrical terminal fastener torque specifications for all models:



M5 terminal fasteners: 44 inch lbs. (5 Nm)
M6 terminal fasteners: 53 inch lbs. (6 Nm)
M8 terminal fasteners: 115 inch lbs. (13 Nm)

Starter motor mounting fasteners:



Hex head bolts: 36 ft. lbs. (49 Nm)
Torx bolts: 32 ft. lbs. (43 Nm)

E36 6-Cylinder Engines
Automatic Transmission Models
  1. Before servicing the vehicle, refer to the Precautions section.
  2. Set the ignition switch to the OFF position.
  3. Disconnect the negative battery cable.
  4. Remove the climate control air intake duct at the rear of the engine compartment as follows:
    1. Release the grille clips at the rear and lift the grille upward from the rubber seal, then remove the seal.
    2. Remove the two self tapping Phillips screws from inside the duct to release the electrical harness housing.
    3. Press the electrical housing downward to expose and remove the two hex head self tapping screws on each side of the duct and lift the duct up and out of the engine compartment.

  5. Remove the intake manifold trim and valve cover trim covers.
  6. Disconnect the ignition coil electrical connectors and ground straps, label for reinstallation and place aside.
  7. Remove the two fasteners that secure the fuel injection electrical connector harness to the rail. Remove the harness and carefully place aside toward the back of the engine compartment behind the right side strut tower.
  8. Remove the intake manifold.
  9. Remove the electrical leads from the starter motor and place aside.
  10. Remove the starter motor mounting fasteners at the transmission bell housing, then remove the two mounting nuts at the L-shaped mounting bracket.
  11. Loosen the L-shaped bracket to engine block mounting bolt slightly, then remove the bolt while supporting the starter motor.
  12. Remove the bracket, then lift the starter motor upward away from the engine.
  13. Visually inspect the starter pinion and ring gears for any signs of damage.
  14. Installation is in reverse order of removal.

Manual Transmission Models
  1. Before servicing the vehicle, refer to the Precautions section.
  2. Set the ignition switch to the OFF position.
  3. Disconnect the negative battery cable.
  4. Raise and safely support the vehicle.
  5. Remove the fasteners for the reinforcement mounted between the frame rails just behind the rear lower control arm bushing brackets. Mark the bar-s direction for proper reinstallation and remove the bar.
  6. Remove the fuel line cover located near the left side rear lower control arm bushing bracket.
  7. Release the fuel lines and reverse light wiring from their routing brackets.
  8. Note the routing of the starter motor electrical wires, remove the wire mounting nuts, and place the wires aside.
  9. Remove the top and bottom starter motor to engine-transmission mounting fasteners.
  10. Remove the two mounting nuts at the L-shaped mounting bracket.
  11. Loosen the L-shaped bracket to engine block mounting bolt slightly, then remove the bolt while supporting the starter motor.
  12. Remove the bracket and carefully lower the starter motor downward away from the engine.
  13. Visually inspect the starter pinion and ring gears for any signs of damage.
  14. Installation is in reverse order of removal.

E46 Models
  1. Before servicing the vehicle, refer to the Precautions section.
  2. Set the ignition switch to the OFF position.
  3. Disconnect the negative battery cable.
  4. Remove reinforcement plate on front axle support.
  5. If equipped vacuum reservoir for exhaust flap.
  6. Unclip fuel line from holders.
  7. Unlock plug of crankshaft pulse generator and disconnect.
  8. Remove nut and disconnect battery positive leads from starter motor.
  9. Remove nuts.
  10. Remove lines from starter motor.
  11. Remove both starter motor mounting bolts on transmission: Release starter mounting bolts from transmission output end with a long extension and a universal joint.
  12. Withdraw starter motor from transmission flange and remove towards bottom.
  13. To install, reverse removal procedure.

E60 & E85 Models

CAUTION
No steel screws/bolts may be used due to the threat of electrochemical corrosion. A magnesium crankcase requires aluminum screws/bolts exclusively. Aluminum screws/bolts must be replaced each time they are released. The end faces of aluminum 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).

  1. Before servicing the vehicle, refer to the Precautions section.
  2. Set the ignition switch to the OFF position.
  3. Disconnect the negative battery cable.
  4. Remove intake manifold.
  5. Unlock electrical plug and remove. Unfasten nut. Remove battery positive lead.
  6. Remove bolts and remove starter motor.
  7. To install, reverse removal procedure. Check starter pinion and ring gear for damage, replace starter motor if necessary. Replace aluminum screws.

E65 Models
  1. Before servicing the vehicle, refer to the Precautions section.
  2. Set the ignition switch to the OFF position.
  3. Disconnect the negative battery cable.
  4. Remove reinforcement plate. Remove right exhaust manifold
  5. Remove heat shield.
  6. Unlock electrical plug and remove. Unfasten nut. Remove battery positive lead.
  7. Release screws and pull starter motor out of transmission mounting and remove.
  8. To install, reverse removal procedure. Check starter pinion and ring gear for damage, replace starter motor if necessary. Replace aluminum screws.

M42 & M44 Engines
  1. If needed, read the stored fault memories from the control module.
  2. Relieve the residual fuel system pressure. For details, refer to Section 5.
  3. Set the ignition switch to the OFF position.
  4. Disconnect the negative battery cable.
  5. Remove the mounting fastener for the dipstick guide tube, remove the guide tube and O-ring and plug the hole in the oil pan with a suitable shop towel.


NOTE
The Torx® fasteners used to mount the starter are removed with an E-12 sized socket.

  1. The following two procedures can be performed working from above or from underneath the vehicle after the vehicle is raised and safely supported:
    1. Label and remove the wires from the starter motor solenoid.
    2. Remove the top starter motor mounting bolt.

  2. Raise and safely support the vehicle.
  3. Place a suitable drain pan below the fuel lines. Label, then carefully remove the fuel lines
  4. If not performed from above:
    1. Label and remove the wires from the starter motor solenoid.
    2. Remove the top starter motor mounting bolt.

  5. Remove the lower starter motor mounting bolt.
  6. Move the starter motor assembly out and downward, then rotate counterclockwise to remove, taking care not to damage the electrical leads.
  7. Visually inspect the starter pinion and ring gears for any signs of damage.
  8. Installation is the reverse of the removal procedure making sure to re-code the radio as necessary and tighten the retainer as follows:

    M5 terminal fasteners: 44 inch lbs. (5 Nm)
    M6 terminal fasteners: 53 inch lbs. (6 Nm)
    M8 terminal fasteners: 115 inch lbs. (13 Nm)
    Hex head bolts: 36 ft. lbs. (49 Nm)
    Torx® bolts: 32 ft. lbs. (43 Nm)




Click image to see an enlarged view

Fig. A view of the starter motor mounting fasteners and dowel pin. The mounting bolts are threaded into the starter motor



Click image to see an enlarged view

Fig. The starter motor mounting bolts are a different size than the transmission-to-engine mounting bolts

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2. Relieve the residual fuel system pressure.
  3. Set the ignition switch to the OFF position.
  4. Disconnect the negative battery cable.
  5. Remove the mounting fastener for the dip stick guide tube, remove the guide tube and O-ring and plug the hole in the oil pan with a suitable shop towel.
    NOTE
    The torx fasteners used to mount the starter are removed with an E-12 sized socket.

  6. The following two procedures can be performed working from above or from underneath the vehicle after the vehicle is raised and safely supported:
    1. Label and remove the wires from the starter motor solenoid.
    2. Remove the top starter motor mounting bolt.

  7. Raise and safely support the vehicle.
  8. Place a suitable drain pan below the fuel lines. Label, then carefully remove the fuel lines
  9. If not performed from above:
    1. Label and remove the wires from the starter motor solenoid.
    2. Remove the top starter motor mounting bolt.

  10. Remove the lower starter motor mounting bolt.
  11. Move the starter motor assembly out and downward, then rotate counterclockwise to remove, taking care not to damage the electrical leads.
  12. Visually inspect the starter pinion and ring gears for any signs of damage.
  13. Installation is in reverse order of removal.

M50/M52/S50 Engines
  1. Disconnect the negative battery cable.
  2. On 6-cylinder engines with 6 identical intake tubes, it may be necessary to remove No. 6 intake tube for clearance. On 4-cylinder vehicles, remove the intake cowl from the mixture control unit.
  3. On the 5 Series models, make sure the engine is cool. Drain some coolant from the cooling system and then remove the expansion tank.
  4. Operate the brake pedal hard 20 times. Disconnect the power steering line that would otherwise prevent access to the starter.
  5. Cut off the straps and remove the solenoid switch insulating cover, located right near the solenoid.
  6. Cut off the straps and remove the solenoid switch insulating cover, located right near the solenoid.
  7. Remove the starter solenoid wire leads, marking them for later installation, unless they have already been removed. On 4-cylinder vehicles, disconnect the mounting bracket at the block.
    NOTE
    Remove the accelerator cable holder on automatic transmission equipped vehicles.

  8. Unbolt and remove the starter.
    NOTE
    On the 5 Series models, it may be necessary to use a box wrench with an angled handle to unscrew the main starter mounting bolts.


To install:

  1. Install the starter and install the retaining bolts. Install all removed components on all vehicles.
  2. Make sure to reconnect all hoses and refill and bleed the cooling system or power steering system.
  3. Where the solenoid switch cover has been unstrapped, reinstall it with new straps to locate it properly for electrical safety.

M60/M62 Engines
  1. Disconnect negative battery cable. Lift and safely support the vehicle.
  2. Remove the splash guard.
  3. Remove the heat baffle plates on the right side of the engine, on the starter motor, and from in front of the front axle carrier.
  4. Remove the electrical leads from the starter motor.
  5. Remove the mounting bolts for the starter motor. Remove the starter motor by lifting out from the back of the ring gear, and remove the starter downwards.

To install:

  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2. Connect the wires to the original locations on the solenoid. If the battery cable connection is all metal, torque to 3.6-4.4 ft. lbs. (5-6 Nm). If the battery cable connection is plastic, torque to 0.7-1.1 ft. lbs. (1.0-1.5 Nm).
  3. Install the heat baffles that were previously removed, and the splash guard.
  4. Lower the vehicle, and connect the negative battery cable.

S14 And M20 Engines
  1. Disconnect the negative battery cable.
  2. Remove the intake manifold assembly. Drain the coolant and disconnect the coolant return pipe to allow the starter to be removed from the engine compartment.
  3. Disconnect the wires from the solenoid after noting their locations.
  4. Remove the starter mounting fasteners at the bell housing. A curved-shaped (horseshoe) wrench may be necessary to access the top mounting fastener.
  5. Remove the rear mounting bracket and remove the starter.
  6. Visually inspect the starter pinion and ring gears for any signs of damage.

To install:

  1. Install the starter and tighten the mounting nuts and bolts, as follows:
    1. Starter motor electrical terminal fastener torque specifications:

      M5 terminal fasteners: 44 inch lbs. (5 Nm)
      M6 terminal fasteners: 53 inch lbs. (6 Nm)
      M8 terminal fasteners: 115 inch lbs. (13 Nm)

    2. Starter motor mounting fasteners:

      Hex head bolts: 36 ft. lbs. (49 Nm)
      Torx® bolts: 32 ft. lbs. (43 Nm)


  2. Connect the wires to the original locations on the solenoid.
  3. Connect the coolant return line.
  4. Fill and bleed the cooling system.
  5. Install the intake manifold assembly.
  6. Connect the negative battery terminal.
  7. Re-code the radio as necessary.

Testing & Troubleshooting



Feed Circuit Resistance Test

Before proceeding with this test, refer to the battery tests and starter feed circuit test. The following test will require a voltmeter, which is capable of accuracy to 0.1 volt.


CAUTION
The ignition system must be disabled to prevent engine start while performing the following tests.

  1. Disable the ignition system.
  2. With all wiring harnesses and components (except for the coils) properly connected, perform the following:
    1. Connect the negative (-) lead of the voltmeter to the negative battery post, and the positive (+) lead to the negative (-) battery cable clamp. Rotate and hold the ignition switch in the STARTposition. Observe the voltmeter. If the voltage is detected, correct the poor contact between the cable clamp and post.
    2. Connect the positive (+) lead of the voltmeter to the positive battery post, and the negative (-) to the positive battery cable clamp. Rotate and hold the ignition switch key in the STARTposition. Observe the voltmeter. If voltage is detected, correct the poor contact between the cable clamp and post.
    3. Connect the negative lead of the voltmeter to the negative (-) battery terminal, and positive lead to the engine block near the battery cable attaching point. Rotate and hold the ignition switch in the START position. If the voltage reads above 0.2 volt, correct the poor contact at ground cable attaching point. If the voltage reading is still above 0.2 volt after correcting the poor contact, replace the negative ground cable with a new one.

  3. Refer to removal and installation procedures to gain access to the starter motor and solenoid connections. Perform the following steps:
    1. Connect the positive (+) voltmeter lead to the starter motor housing and the negative (-) lead to the negative battery terminal. Hold the ignition switch key in the START position. If the voltage reads above 0.2 volt, correct the poor starter to engine ground.
    2. Connect the positive (+) voltmeter lead to the positive battery terminal, and the negative lead to the battery cable terminal on the starter solenoid. Rotate and hold the ignition key in the STARTposition. If the voltage reads above 0.2 volt, correct poor contact at the battery cable to the solenoid connection. If the reading is still above 0.2 volt after correcting the poor contacts, replace the positive battery cable with a new one.
    3. If the resistance tests did not detect feed circuit failures, refer to the starter solenoid test.


Feed Circuit Test

CAUTION
The ignition system must be disabled to prevent engine start while performing the following tests.

  1. Connect a volt-ampere tester (multimeter) to the battery terminals.
  2. Disable the ignition system.
  3. Verify that all lights and accessories are off, and the transmission shift selector is in Park (automatic) or Neutral (manual). Set the parking brake.
  4. Rotate and hold the ignition switch in the START position. Observe the volt-ampere tester:

    If the voltage reads above 9.6 volts, and the amperage draw reads above 250 amps, go to the starter feed circuit resistance test (following this test).
    If the voltage reads 12.4 volts or greater and the amperage reads 0-10 amps, refer to the starter solenoid and relay tests.



WARNING
Do not overheat the starter motor or draw the battery voltage below 9.6 volts during cranking operations.

  1. After the starting system problems have been corrected, verify the battery state of charge and charge the battery if necessary. Disconnect all of the testing equipment and connect the ignition coil cable or ignition coil connector. Start the vehicle several times to assure the problem was corrected.

Starter/Ground Cable Test

When performing these tests, it is important that the voltmeter be connected to the terminals, not the cables themselves.

Before testing, assure that the ignition control module (if equipped) is disconnected, the parking brake is set, the transmission is in Park (automatic) or Neutral (manual), and the battery is fully charged and in good condition.

  1. Check voltage between the positive battery post and the center of the B+ terminal on the starter solenoid stud.
  2. Check voltage between the negative battery post and the engine block.
  3. Disconnect the ignition coil wire from the distributor cap and connect a suitable jumper wire between the coil cable and a good body ground.
  4. Have an assistant crank the engine and measure voltage again. Voltage drop should not exceed 0.5 volts.
  5. If voltage drop is greater than 0.5 volts, clean metal surfaces. Apply a thick layer of silicone grease. Install a new cadmium plated bolt and star washer on the battery terminal and a new brass nut on the starter solenoid. Retest and replace cable not within specifications.

Testing Preparation

NOTE
The air temperature should be between 59-100°F (15-38°C) before any testing.

The starting system consists of an ignition switch, starter relay, neutral safety switch, wiring harness, battery, and a starter motor with an integral solenoid. These components form two separate circuits: a high amperage circuit that feeds the starter motor up to 300 or more amps, and a control circuit that operates on less than 20 amps.

Before commencing with the starting system diagnostics, verify:



The battery posts and terminals are clean.
The alternator drive belt tension and condition is correct.
The battery state-of-charge is correct.
The battery cable connections at the starter and engine block are clean and free from corrosion.
The wiring harness connectors and terminals are clean and free from corrosion.
Proper circuit grounding.



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