BMW 318/325/M3/525/535/M5 1989-1993 Repair Information

Starter

Print

TESTING



See Figure 1

The starter can be inspected for incorrect operation through visual and operational means. A series of simple checks can help locate the problem with the starting system. The starter consists of 2 main parts, the solenoid and the starter motor. The solenoid engages the starter pinion and acts a high current switch for the starter motor. Note that there is a thick battery cable leading to the solenoid and a braided copper lead going from the solenoid into the motor body. There is a smaller wire going from the ignition switch to the 50 terminal of the solenoid. This is the control signal that actuates the solenoid which in turn passes the larger current from the battery to the starter motor via the braided copper lead.

If the starter will not operate at all, check the condition of the battery. The starter needs a good strong charge to operate correctly. Jump start the car in the proper sequence. If the starter operates, check the charging system for faults. If the starter will not operate, check that all the connections from the battery to the starter are intact and clean. Check that battery voltage is present at the thick cable connection on the solenoid.

If all the connections are clean and tight to the starter, including the engine ground strap, check that the solenoid is getting the start signal from the ignition switch. Check that battery voltage is present at terminal 50 on the solenoid when the ignition switch is turned. If voltage is present, then the solenoid or starter is bad. The solenoid and starter is typically replaced as a unit.

If the solenoid clicks when the ignition switch is turned, but the starter does not crank, check that the copper braid from the starter motor to the solenoid is intact and the connection is tight. If the connection is clean and tight, check if battery voltage is present at the copper braid when the ignition switch is turned. If voltage is present, the starter is bad. If no voltage present, the solenoid is bad.

If the starter cranks slowly, check the condition of the battery and cable connections. This condition is typically caused by a low charge on the battery or high resistance cable connections. Clean all the cable connections and charge the battery. If this doesn't help, it is possible that the front bearing in the starter nose is binding. Replace the starter in this case.

Visual checks of the starter body can show a loose solenoid. Sometimes the solenoid mounting bolts can work loose causing the solenoid to back off from the starter body. This will cause incomplete engagement of the pinion and hard starting.

When the starter is removed, check the pinion gear teeth for chips and wear. Replace the starter if the pinion is damaged. The pinion can be damaged if the starter is engaged while the engine is running or if the starter grinds on engagement. Check the condition of the flywheel ring gear if the pinion is found to be damaged. The ring gear tends to get damaged as the pinion is damaged.



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of a typical Bosch starter

REMOVAL & INSTALLATION E30 3 Series



WITH M42 ENGINE
  1. Disconnect the negative battery terminal. Remove the air cleaner assembly and the hose leading to the throttle body.
  2.  
  3. Remove the intake manifold support. Mark the electrical connectors on the lead duct and disconnect.
  4.  
  5. Move the lead duct towards the side of the engine compartment to access the starter.
  6.  
  7. Mark and remove the wires from the starter. Remove the starter mounting nuts and remove the starter.
  8.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Replace the lead duct and connect the electrical connector in their original positions. Be sure the rubber grommets are installer correctly to prevent water from entering the lead duct.
  6.  
  7. Install the intake manifold support and tighten to 15-17 ft. lbs. (20-24 Nm). Install the air cleaner assembly and connect the negative battery terminal.
  8.  

WITH M20 ENGINE
  1. Disconnect the negative battery terminal.
  2.  
  3. Remove the air cleaner assembly. Drain the coolant and disconnect the heater hoses to allow the starter to be removed from the engine compartment.
  4.  
  5. Disconnect the wires from the solenoid after noting their locations.
  6.  
  7. Remove the starter mounting nuts at the bell housing. You may need to use a curved wrench to reach the upper nut.
  8.  
  9. Remove the rear mounting bracket and remove the starter.
  10.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Connect the heater hoses, fill and bleed the cooling system. Install the air cleaner assembly. Connect the negative battery terminal.
  6.  

WITH S14 ENGINE
  1. Disconnect the negative battery terminal.
  2.  
  3. 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.
  4.  
  5. Disconnect the wires from the solenoid after noting their locations.
  6.  
  7. Remove the starter mounting nuts at the bell housing. You may need to use a curved wrench to reach the upper nut.
  8.  
  9. Remove the rear mounting bracket and remove the starter.
  10.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Connect the coolant return line, fill and bleed the cooling system. Install the intake manifold assembly. Connect the negative battery terminal.
  6.  

E36 3 Series

WITH M42 ENGINE
  1. Disconnect the negative battery terminal. Mark and remove the wires from the solenoid.
  2.  
  3. Remove the upper starter bolt from inside the engine compartment.
  4.  
  5. From under the car remove the lower starter bolt. Remove the starter from the car.
  6.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Connect the negative battery terminal.
  6.  

WITH M50 ENGINE

See Figures 2 and 3

Click image to see an enlarged view

Fig. Fig. 2: Disconnect the starter wires from the solenoid



Click image to see an enlarged view

Fig. Fig. 3: Upper starter mounting bolt

  1. Disconnect the negative battery terminal. Remove the air cleaner assembly.
  2.  
  3. Remove the intake manifold. Mark and remove the wires from the solenoid.
  4.  
  5. Remove the upper starter bolt from inside the engine compartment.
  6.  
  7. From under the car remove the lower starter bolt. Remove the starter from the car.
  8.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Install the intake manifold. Connect the negative battery terminal.
  6.  

E34 5 Series

WITH M20 ENGINE
  1. Disconnect the negative battery terminal.
  2.  
  3. Disconnect the wires from the solenoid after noting their locations.
  4.  
  5. Remove the starter mounting nuts at the bell housing. You may need to use a curved wrench to reach the upper nut.
  6.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Connect the negative battery terminal.
  6.  

WITH M50 ENGINE
  1. Disconnect the negative battery terminal. Disconnect the alternator cooling duct and remove the air cleaner assembly. Remove the intake manifold.
  2.  
  3. Disconnect the wires from the solenoid after noting their locations.
  4.  
  5. Remove the starter mounting nuts at the bell housing. You may need to use a curved wrench to reach the upper nut.
  6.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Install the intake manifold, alternator cooling duct and the air cleaner assembly. Connect the negative battery terminal.
  6.  

WITH M30 ENGINE
  1. Disconnect the negative battery terminal. Remove the screws from the coolant expansion tank and move to the side to gain better access to the mounting bolts.
  2.  
  3. Disconnect the wires from the solenoid after noting their locations.
  4.  
  5. Remove the starter mounting nuts at the bell housing. You may need to use a curved wrench to reach the upper nut.
  6.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Connect the negative battery terminal.
  6.  

WITH S38 ENGINE
  1. Disconnect the negative battery terminal. Remove the intake manifold.
  2.  
  3. Disconnect the wires from the solenoid after noting their locations.
  4.  
  5. Remove the starter mounting nuts at the bell housing. You may need to use a curved wrench to reach the upper nut.
  6.  

To install:
  1. Install the starter and tighten the mounting nuts and bolts to 34-36 ft. lbs. (47-50 Nm).
  2.  
  3. 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).
  4.  
  5. Install the intake manifold, alternator cooling duct and the air cleaner assembly. Connect the negative battery terminal.
  6.  

SOLENOID REPLACEMENT



It is most common to replace the starter and solenoid as an assembly. Finding a replacement solenoid is not as easy as finding a complete new or rebuilt starter. 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.

  1. Remove the starter.
  2.  
  3. Disconnect the copper braid lead from the solenoid terminal. Be careful not to twist and pull on the lead as the nut is removed.
  4.  
  5. Remove the 2 or 3 screws at the nose end of the solenoid.
  6.  
  7. Remove the solenoid. Be careful not to lose the spring in the solenoid.
  8.  

To install:
  1. Install the solenoid onto the body of the starter. Coat the threads of the screws with threadlocker compound and tighten.
  2.  
  3. Connect the copper braid lead to the solenoid terminal. Be careful not to twist or pull on the lead as the nut is tightened.
  4.  
  5. Install the solenoid.
  6.  

 
label.common.footer.alt.autozoneLogo