Mandatory Electrical Components to Start a '47 DeSoto

[Sniper]

You would think so, but I assume it doesn't?

[Bingster]

I really don't know.  There is a guy on YouTube who has a seven-part series and in-depth look at this very same solenoid.  I've watched it several times and deduce what I mentioned. He says that if you bridge the lower two large posts the starter will spin but not crank the engine, which he says means the starter is okay but possibly the solenoid is not.  I may have to bite the bullet and remove the starter and bench test it.

[kencombs]

4 hours ago, Bingster said:

I really don't know.  There is a guy on YouTube who has a seven-part series and in-depth look at this very same solenoid.  I've watched it several times and deduce what I mentioned. He says that if you bridge the lower two large posts the starter will spin but not crank the engine, which he says means the starter is okay but possibly the solenoid is not.  I may have to bite the bullet and remove the starter and bench test it.

You can't really do anything on the bench with the starter assembled that can't be done on the engine.   Remove all wires then test solenoid windings, contact resistance etc.

But all wires should be disconnected as shorts in wiring may be misconstrued.

 

If I were working on it the first thing would be to unhook the wires then make up a couple of test leads. Prably 12ga wire with clips long enough to reach a battery, either in the car or just one to test.   clip one lead on the solenoid 'small post' and the other end to the battery.   At this point polarity doesn't matter.  Now use the other lead clipped to the other 'small post' and momentarily touch the other end to the other battery post.   If it clicks it is likely working, if not use your meter to test for opens or grounds in the solenoid coil.   There are other tests, but that's where I'd start.

Edited October 24, 2023 by kencombs

[Bingster]

I just accidentally ran across a solenoid relay the exact type that I need to replace the possibly bad one. I just figured that in case the relay is bad, I would be very glad to have such a rare part.

 

I don't know if I could repair the solenoid with starter in the car. I wish I could.

[kencombs]

14 hours ago, Bingster said:

I just accidentally ran across a solenoid relay the exact type that I need to replace the possibly bad one. I just figured that in case the relay is bad, I would be very glad to have such a rare part.

 

I don't know if I could repair the solenoid with starter in the car. I wish I could.

I didn't mead 'repair' in the car, just testing.  That is as easily done on the car as on the bench.  And without the weightlifting workout.

[Bingster]

I'm going to try your procedure to rule out anything that could be done with the starter still in the car. 

[Bingster]

Well, I discovered in messing about that I had the generator wiring inverted. I went by what I thought was the diagram location of the A & F posts on the gen.  I had the ground terminal from the upper left post on the solenoid going to Field on the gen and the wires leading to the voltage regulator wrong as well. 

 

So I put them where they ought to be, I thought,  and tried doing what kencombs suggested. Got a big spark when I connected a wire from the upper right left post of the solenoid to the hot negative on the battery.

 

That's when I looked closely at the wiring diagram and saw that it was just possible that the wire from the upper left ground post of the solenoid should actually be put onto the G screw on the gen.  This may seem obvious to you folks, but the wires that were coming off the gen on the diagram were obviously misinterpreted.

 

So I had the ground wire on the solenoid going to field on the gen and nothing really grounded I guess cause nothing was attached to G on the gen.

 

I haven't tried another go at it yet.