Help Please A Problem no one has been able to diagnose

GS400M03

Newbie
Hello All, new to the forum. I really need your expertise with this, all my resources are baffled

I just picked up a 1967 GS400 Convert automatic no air.

I was cleaning up the underside of the front lower motor from years of leaks, I grabbed the Positive cable to the starter and started wiping the oil off of it and the starter started spinning full speed. It did not engage the flywheel thankfully. I quickly lowered the car so I could disconnect the cable at the battery, by the time I disconnected it, the spinning had slowed down to almost a stop. The cable and starter were warm, my guess is it was spinning for about 60 seconds.

The wiring gutter is in tact on the Passenger-side of the block with the aluminum cover in place. All the wiring was tight and separated. I removed all the wiring and see no breaks or bare wiring. Any idea what would caused the starter to spin like that without engaging the flywheel? What should I be checking for with wiring and starter?

I only thing I noticed was the ring terminal of the yellow starter wire was close to the battery cable stud.

Prior to this event all starting events were normal. I checked the battery and it was at 85% charged after the event.
 
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I would think that the only scenario that could have caused that would be, the positive cable to the starter is always hot, if it was loose on the starter, somehow it came in contact with the "other side" of the relay where the positive goes into the starter motor, after the relay ( the metal band from the bottom of the relay that disappears through the grommet into the motor). It did not go through the relay because the starter would have engaged to complete the circuit. The condition or separation of the wires did not cause this problem, they could cause other problems, like big sparks!.

I would suggest checking all the wires on the solenoid for satisfactory separation and tightness.
 
The starter motor is always connected to positive. When you turn the ignition key, the relay in the solenoid completes the circuit and it pulls a plate that connects the solenoid's positive terminal with the starter's positive terminal. This same piston has a lever that pushes out the shaft in the starter to connect the gear with the flywheel. In normal position only the solenoid positive terminal is connected to the battery. Through this plate the starter gets powered where a heavy rotor spins up that spins a shaft that ends with a gear that is sitting on the flywheel -> it starts cranking the engine.

What you described above can only happen if you apply 12V to the motor's positive terminal _directly_. If you used any fluids, touched the terminal with your hand, or with a wrench or any tool that connected the 2 positives then your starter motor could have spinned up _without_ the piston pushing the gear. The rotor in the starter is very heavy, because you need a good amount of torque to spin the flywheel, so it spins up to full speed without load relatively slowly.

By "accident" I have a starter in my garage.
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_NEVER_EVER_ clean your car, remove wires, touch any terminals when you have the battery connected! Always disconnect the battery before you touch the electronics!
 
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Sounds like you have an internal issue with the solenoid. When you grabbed the battery cable at the starter to clean it you made a connection within the solenoid directly to the starter motor. This is most likely due to a short in the solenoid. It works normally when you turn the key to start the car because the connections in the solenoid are at rest and in normal positions. I would bet if you change the solenoid your problems will go away. Actually, it was a good thing you found it this way as opposed to being on the road and having the starter start spinning and then burn up from overheating. This is certainly a weird problem but these things happen due to faulty parts and/or all the vibrations that go on in the starter through normal use. Good luck with the problem...sounds like a great car, Ken
 
This happens if the always hot battery cable shorts to the purple start wire. Undo the purple wire from the solenoid and check it for power with ignition off, if it has power it is shorted to an always hot source.. When you turn the switch to start, the purple wire supplies batter voltage to the Solenoid S Terminal. When the solenoid pulls in it contacts a tab which supplies batter voltage to the coil. This bypasses the resistor wire which lowers voltage to the coil. During crank battery voltage drops to about 10 and when combined the resistor wire the voltage at the coil would be too low. If you take the purple wire off the solenoid and it still cranks there is an internal short in the solenoid, I have never seen that failure. The most common failure is overheating the harness and melting the purple wire into a B+ wire. I forget exactly what happens if you switch the Coil wire and the switch wires at the starter it would not work, just i forget the failure mode. . If you have a damaged harness someone like Painless can probably get you a better than new harness.



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