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How to Tell a Bad Starter Drive

The proper nomenclature for a starter drive is a Bendix. The starter motor drive shaft has a spiral groove on which the Bendix rides. The Bendix is normally posed next to the motor when not in operation. When the motor is actuated, the spinning of the motors shaft causes the Bendix, complete with gear, to move away from the motor where it engages the flexplate gear. When the motor stops turning, spring pressure retracts the Bendix to its stationary position.

Instructions

1

Try to start the engine. If you hear a loud whirring noise, the starter motor has engaged and there is definitely something wrong with the starter or flexplate gear. If you hear no sound, the starter has not actuated.

2

Open the hood and test the battery voltage with the voltmeter. Connect the red voltmeter lead to the positive terminal on the battery and the black lead to the negative terminal. There should be 12.5 volts or better. If not, charge the battery and test again. If it does not take a charge replace it. If it does take a charge, watch the voltmeter as a helper turns the key to start. If the voltage remains constant, a wire or solenoid problem exists. If the voltage drops below 10.5 volts replace the battery. Check the alternator output if the battery took a charge.

3

Check the power to the starter solenoid B+ terminal. This is the wire cable directly from the battery to the solenoid. Place the black voltmeter lead on a good ground and probe the solenoid terminal with the red wire. Battery voltage should be present if the wire and battery terminals are good.

4

Check the S-terminal on the solenoid. This is the small terminal that receives power from the ignition switch that actuates the starter. Remove the S-terminal small wire and probe it while a helper turns the key to the start position. It should have power. If it doesnt, the ignition switch is bad. If there is power at both terminals and the starter just clicks or makes no noise at all, replace the starter. If the starter runs but does not turn the engine proceed to the next step.

5

Remove the negative cable on the battery using a wrench. Raise the front of the vehicle with the floor jack and place the jack stands under the frame. Lower the vehicle so that it rests on the jack stands.

6

Remove the starter bolts with a socket and pull the starter out. Disconnect the large primary power wire on the B+ terminal and the small wire on the S-terminal using a wrench. Lay the starter on the ground in front of the vehicle.

7

Test the starter using the jumper cables. Connect the black lead to the negative terminal on the battery and the other end of this cable to the body of the starter. Connect the red lead to the positive terminal on the battery. Take the red lead in hand and momentarily touch the large stud just below the large B+ terminal. Watch the starter Bendix. It should immediately snap out to the end of the starter motor shaft as the motor is spinning. As soon as the motor stops the Bendix should retract. If not, replace the starter. If it does operate perfectly, the problem is the flexplate gear. The ring gear that surrounds the flexplate is what the Bendix engages to turn the engine. This requires removing the transmission and torque converter in order to replace.

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