48 P15 Starter

[pkelley3700]

Good afternoon! My apologies if there is an existing thread on this topic, I could not find it.

 

I was working on turning over my engine to check for spark and compression when the starter quit. I was using a jump box running from positive to ground and touch ground to the threaded pole on starter. I removed the starter and disassembled to clean and inspect. Everything seems to be fine. I notice that when the nut on the threaded pole is loose, the starter spins, but when it is tight it does nothing. When it spins, however the bendix does not engage. Is this possibly a field Coil issue? Is it ok to use a jump box to test this 6 volt starter? 

Thanks

 

Edited December 17, 2022 by pkelley3700

[Los_Control]

Not sure what starter you are working with ... I assume it has a solenoid on the firewall?

My truck has a stomp starter on the floor with solenoid attached to the starter .... the solenoids need to be cleaned for good connections.

Possibly your loose "pole" on starter needs cleaning also? ...... Clean electrical connections can be a headache on a vehicle that has sat for a long time.

 

FWIW, your car originally would be positive ground, so your connections are correct.

Just so you know, the starter does not care & will work positive or negative ground. .... So long as it is not connected to the cars wiring

[pkelley3700]

That is correct, the solenoid is separate. Wiring is completey shot on the rig. The loose terminal is where the ground wire connects to the starter. Not a stomp starter type, it's push button. Thanks for the feedback.

 

 

 

 

 

 

[Los_Control]

I wonder if you have a grounding issue. .... Is there some sort of fiber washer missing to keep the stud away from the case?

The stud needs to be tight, you may have to go back in & see whats up.

 

Hopefully someone comes along with a better answer. .... either way the stud needs to be snugged up tight, not left loose.

 

I wonder if you reversed polarity & ran it negative ground, if the problem goes away?

Would confirm a ground issue.

[pkelley3700]

Hmm, good thought. There are fiber washers in middle and top, but I am not sure about the inner washer.

 

 

 

 

 

 

 

 

 

 

[SteveR]

Did you look at the commutator where the brushes ride and what do the brushes look like? Is the commutator brass color or black black and grooved.

[pkelley3700]

Still copper or brass colored. The brushes aren't too bad either.

[SteveR]

9 minutes ago, pkelley3700 said:

Still copper or brass colored. The brushes aren't too bad either.

then start checking your grounds and voltages

[kencombs]

I don't think polarity really makes any difference to the starter, but the ground (black lead) from the charger/booster goes to the stud on the starter, the 'hot' (red) red goes to the starter case.   You terms above kinda confused me.  The stud must be isolated from the case.  Check with a meter.  It would be good practice to just replace all the parts surrounding it, washers/bushings etc, with new just to be sure.

[pkelley3700]

So there should not be continuity from the post to the case? 

[kencombs]

1 hour ago, pkelley3700 said:

So there should not be continuity from the post to the case? 

Exactly, the current flow is from the post through the internal wiring and then to ground.

[pkelley3700]

I will check on that and report back. 

[SteveR]

Here is your wiring diagram

Edited December 18, 2022 by SteveR

[pkelley3700]

Thanks for that. It's a big help!

[Sam Buchanan]

Something you must have if you own an old Mopar:

 

https://www.amazon.com/Plymouth-Service-Manual-1946-1951-Models/dp/B002JY9KVK/ref=sr_1_1?crid=UKROJD7QZURC&keywords=1948+plymouth+manual&qid=1671419689&sprefix=1948+plymouth+manual%2Caps%2C102&sr=8-1

 

[pkelley3700]

Cool. Definitely have to pick that up.

[Sniper]

Rock auto sells it in CD format, if your laptop has a CD player.  I had to dust off my old laptop to copy it over to a thumb drive. They also sell a hard copy version.  But the CD also comes with parts manuals.

[pkelley3700]

Apologies for taking so long to follow up. Looks like a new starter will be in order. The field Coil has a short in it. I could rebuild it, but I may just spring for a new one. Thanks for all the advice!