Starter continues to spin.
 

1970 T/A. After releasing the key, the starter motor continues to spin. I must remove battery cable to get starter to stop spinning. The starter motor was just professional rebuilt by an electrical specialty shop and included a new solenoid. I just took the starter back out and to another specialty shop that only does starters/alternators and it tested out just fine. The battery is new and fully charged and has 12.7 volts at rest. Replaced the ignition key/cylinder mechanism with new, problem persists. Replaced the the ignition switch on steering column with new unit from NAPA, problem persists. The battery cable and the wiring harness are new and connections are clean and tight. None of these wires are touching each other. Now that I have replaced all of these items, I'm not sure what my next step should be. Any ideas?

When I replaced the solenoid in my tractor the same thing happened. The solenoid was not releasing. Bench tested fine. I got rid of the cheap Chinese crap solenoid and was able to find an NOS solenoid. Alls been good for over a year.

This is best to do with the starter off the engine but still connected to the wiring. Remove the nut holding the small wire (I believe it's purple) and have someone crank the engine. Have them stop cranking and you remove the purple wire from the starter. Does it keep cranking? If yes the problem is in the starter. If no then you are going to have to trace back and see what is feeding the purple wire. If you already replaced the ignition switch I would look at the neutral safety switch or the firewall connector. The Purple wire is connected to the "S" terminal isn't it?

Purple goes to "S" and yellow goes to "R". Can I remove the purple wire and use a jumper wire from the purple to the post on the solenoid where purple belongs?

Yes, you can..


Is the ignition system still points? If not, remove the yellow wire from "R" and try again. What happens?

It still has points and everything is stock on the car.

This will most likely be a mechanical problem instead of electrical.

Plunger in the solenoid is being held back by mechanical force instead of magnetic when you let off on the ignition switch. Plunger drawn in is what pushes the disc (under the solenoid cap) against the battery and starter motor lugs. As long as the disc makes contact the starter motor is going to run.

There's a few things that can make this happen, that just looking during a bench test wont show.

Lack of slack between plunger, throwout lever and bendix/drive gear, with solenoid engaged, would be highly suspect. Or make that slack in the wrong direction.

Weak disc return spring and weak plunger return spring don't help when it comes to the disc breaking contact and solenoid disengaging.

Over extension of bendix from broke or missing parts, on drive end of armature, will let the bendix go too deep in the ring gear and use up the slack needed for solenoid disc to disengage.

Slack needed can be tested on the bench with plunger return spring removed. Pry the bendix towards the nose and see if the plunger is pushing the disc far enough to make contact with the lugs.

Mark Stellar, here on PY (stellar), may have specs to get all the parts working together like they should.

Just some thoughts
Clay

Clay has it pretty well covered. The only other thing I could add is the drive pinion may be too tight against the ring gear and not letting it release. An additional starter shim may help. How much is the starter shimmed now?

I just measured the two starter shims and the combined thickness is 7/32. This car has been restored top to bottom and most everything is new. The first 10-12 times I started the motor, there were no problems with the the starter. Then this problem began. Due to moving from GA to FL and that entire hassle, there are less than 2 miles of "shake down" driving on the car. Once I figure this problem out, I will get the front end aligned and several other details taken care of. Thanks.

If you pull the starter out, take a pic of the drive and the armature shaft in the starter. I just reread your original post. I did assume that after disconnecting the battery and then replacing it the starter is no longer running until you try to restart it. Is this the case?

stellar, the answer to your question is "yes". If I disconnect the starter cable, the starter stop spinning. Then when I reconnect the starter cable the starter is still not spinning. When I then turn the key to start the engine, the starter then continues to run even when the key is released.

Dave

What happens when the engine fires off?

Clay

I'd try putting a stronger spring in the solenoid, or try stretching it out a little to see if it corrects the problem?

:confused:

Update/test results
 

I put a Jumper clip from the "S" side of the solenoid to the disconnected purple wire that normally goes to that post. I then attempted to start the engine and after releasing the key, the starter continued to spin. I then quickly disconnected the jumper wire from the purple wire and the starter still continued to spin. I then had to disconnect the negative battery cable from the battery in order to get the starter to stop spinning. I think this proves that the solenoid is the issue and not the starting circuit? Is this correct and should I replace the solenoid? Thx.

If it were me, I definitely would change the solenoid.

It sounds like a solenoid problem. Probably either the small spring against the solenoid cap is missing or one of small posts under the solenoid cap has twisted and allowing contact to the copper disc when in the energized position. If a replacement solenoid does not correct the problem the drive is getting stuck in the extended position. Be careful not to over tighten the nuts on the small posts.

Thanks everyone, I will purchase a new solenoid today and let you know if that does the trick. Dave

Look for a missing collar and snap-ring on the end of the armature.

I've seen the collars break and fall off. That lets the drive gear over extend (uses up slack) that's needed for the disc to move away from the lugs in the solenoid cap.

Clay

I got bit with this on a reman starter years ago. I had to take it apart to find it out, then went back to the parts store with it to show them. I think the guy who "rebuilt" it forgot to put it back on.

Update on replaced solenoid.
 

I purchased a new solenoid from NAPA and installed it yesterday. I tested the starter and solenoid unit on my bench before installation and it looked, sounded and acted corretly. I then installed it in the motor but I STILL have the same problem. "Starter continues to spin after I release the key and it wont stop spinning until I disconnect the Batter cable". Now I am really stumped! Ideas???