BMW 12411269696 Exchange Starter Motor

This type of starter incorporates a solenoid mounted on the starter body, which, when the ignition switch is operated, moves the starter drive pinion into engagement with the flywheel starter ring gear through the shift lever. As the solenoid reaches the end of its stroke and the pinion is fully engaged with the flywheel ring gear, the fixed and moving contacts close, energizing the starter to rotate the engine. This fractional pre-engagement of the starter drive significantly reduces wear on the flywheel ring gear compared to inertia type starters. To remove the starter, first disconnect the lead from the battery negative terminal, then disconnect the leads from the starter solenoid terminals and release the starter front mounting. Next, unbolt the starter from the bell housing and withdraw it. Installation is simply the reverse of removal.

The starter is a brush type series-wound motor with overrunning clutch, solenoid operated, and the armature shaft is provided with non-adjustable metal bushes that do not need renewal at intervals. The engagement lever is used to shift the pinion in contact with the engine ring gear; when this is done; closing of the solenoid circuit helps turn the engine. When started the rotating ring gears force the pinion to overrun the clutch and armature, it remains engaged until the switch is closed to release otherwise, it goes back to the initial position under the spring pressure. Checking the headlamp when the starter is engaged is a sign of service while a non operational starter should have its connections checked for tight connection and the battery recharged if needed. If the above is not audible the wiring of the starter and connections should be checked. To unmount the starter, it is necessary to unbolt the battery earth cable, and the wiring, and unbolt the fixing bolts after which the starter can be lifted from the engine. For solenoid dismantling, the following steps should be followed, these include; disconnecting the solenoid, removal of screws holding the solenoid, detachment of the solenoid, and removal of the end cap to ensure the shim thickness of the armature was altered to ensure that there is a correct armature end play. Cleaning entails removal of dirt by blowing and also use of brush on the brushes which should be inspected for signs of wear out and replaced if is the case. The surface of the commutator has to be smooth and clean, and should be wiped with a cloth and polished if necessary; as for the armature, it should be checked for any signs of damage. Field coils need insulation breakdown checks and the drive pinion assembly can be wipe clean but no solvent. In particular, bearings must be changed if worn out and solenoids should not be repaired but replaced if found faulty. The reassembly process is done in reversal to the dismantling process; this to allow checking and replacement of loose lubricant and tightening of the parts.

Begin by disconnecting the motor field winding lead from the solenoid terminal.