GMC 1988723 Starter Motor, Remanufactured

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To install the brush assembly to the field frame, first, install the brushes to their holders and then assemble the insulated and grounded brush holders together with the V-spring and locate the unit on its support pin. Push the holders and spring to the bottom of the support and rotate the spring to engage the V in the support slot. Connect the ground wire to the ground brush and the field lead wire to the insulated brush and repeat the operations for the second set. Smear silicone oil onto the drive end of the armature shaft and slide the clutch assembly (pinion to the front) onto the shaft, followed by sliding the pinion stop/retainer onto the shaft with its open end facing away from the pinion. Stand the armature vertically on a piece of wood, position the snap-ring on the end of the shaft, and using a hammer and a piece of hardwood, drive the snap-ring onto the shaft. Slide the snap-ring until it drops into its groove. Install the thrust collar on the shaft so that the shoulder is next to the snap-ring and use pliers to squeeze the thrust collar and stop/retainer together until the snap-ring fully enters the retainer.

Please be aware that the disassembly and testing of the starter motor are critical processes, and it might be advisable for the home mechanic to consider purchasing a new or factory-rebuilt unit instead. However, if the decision is made to overhaul the starter, check the availability of singular replacement components before proceeding. To begin, disconnect the starter motor field coil connectors from the solenoid terminals and unscrew and remove the through bolts. Next, remove the commutator end frame, field frame assembly, and the armature from the drive housing, along with the solenoid and shift lever assembly. Slide the two-section thrust collar off the armature shaft and expose the snap-ring by driving the stop/retainer up the armature shaft using a suitable tube. Extract the snap-ring from its shaft groove and slide the stop/retainer and overrunning clutch assembly from the armature shaft. Proceed to dismantle the brush components from the field frame and release the V-shaped springs from the brushholder supports. Remove the brushholder support pin and lift the complete brush assembly upwards. If the brushes are worn down to half their original length and need replacement, disconnect the leads from the brushes. The starter motor is now completely dismantled, except for the field coils. If the field coils are found to be defective during the tests described later, the removal of the pole shoe screws should be done at a service station with the necessary pressure driver. Clean all components and replace any obviously worn ones. Note that roller-type clutches should not be disassembled and are serviced as complete units. Under no circumstances should the insulation between the commutator segments on molded type commutators be undercut. However, on conventional commutators, undercut the insulation by in using an old hacksaw blade, ensuring the groove is square at the bottom. Once undercutting is complete, brush away all dirt and dust. Clean the commutator by spinning it with number '00' sandpaper wrapped around it (do not use any other abrasive material). If the commutator is severely damaged, it may be turned down in a lathe to provide a new surface, but make sure to undercut the insulation after turning. To test the armature for ground, use a lamp-type circuit tester by placing one lead on the armature core or shaft and the other on a commutator segment. If the lamp lights up, the armature is grounded and needs replacement. To test the field coils for an open circuit, place one test probe on the insulated brush and the other on the field connector bar. If the lamp does not light, the coils are open and must be renewed. To test the field coils for ground, place one test probe on the connector bar and the other on the grounded bush. If the lamp lights up, the field coils are grounded. Finally, remember that the overrunning clutch cannot be repaired, and if it is faulty, it must be replaced as a complete assembly.

To remove and install the starter, begin by disconnecting the negative battery cable and raising the car on jackstands. Remove any starter braces or shields in the way, then remove the starter motor-to-engine bolts and allow the starter to drop down. Disconnect the solenoid wires and battery cable before removing the starter.

Ensure that the speed selector lever is in 'N' or ‘P’ for automatic transaxle or that the clutch pedal is depressed for manual transaxle. Verify that the battery is charged and all cables, at both the battery and starter solenoid terminals, are secure.

Raise the vehicle and support it with jack stands.

Clean the commutator by spinning it with number '00' sandpaper wrapped around it. Do not use any other abrasive material.

During starter installation, be sure to install the shims (if any) that were noted during removal.

Make sure that the shift lever is in Neutral or Park (automatic transmission) or that the clutch pedal is depressed (manual transmission). Also, check that the battery is charged and that all cables, both at the battery and starter solenoid terminals, are secure.

Connect the ground wire to the grounded brush and the field lead wire to the insulated brush.

Remove the starter.

No, there is no adjustment provided for the pinion clearance. If the clearance is incorrect, the starter will have to be dismantled again, and any worn or distorted components renewed.

Run the engine to normal operating temperature, disconnect the battery feed wire to the distributor cap to prevent engine firing during cranking, then connect a voltmeter positive lead to the starter motor terminal of the solenoid and the negative lead to ground. Ignite the switch, take the voltmeter readings once steady, but don't let the starter motor turn for more than 30 seconds at a time. A reading of 9 volts or more with normal cranking speed indicates a good condition, while the same voltage but slow cranking speed denotes a faulty motor.

Disconnect the leads at the starter solenoid, marking each with coded tape for easy identification later.

After removing the snap-ring and overrunning clutch assembly, proceed to dismantle the brush components from the field frame and release the V-shaped springs from the brushholder supports. Remove the brushholder support pin and lift the complete brush assembly upwards.

The fault lies in the main solenoid contacts or the starter motor itself.