55 Generator trouble-I think I screwed up

[Jeff Rosansky CLC #28373]

Ok. I think we were stupid. Let me explain.

55 Caddy. Glove box left open with light on for a couple weeks with battery tender on. When we finally started it, generator not charging with gen light on. Posted that earlier and advice was to ground the field. Did that and engine lugged a bit and got 15 volts. Determined regulator bad. Got another one and son installed it but didn't start it. After a few days I got antsy because he hadnt started it because he was doing his finals (Imagine working on finals instead of the car). Well here is where i/we were stupid. He said it was installed and we discussed polarizing the regulator but he didn't do it. So, impatient me, I started it. Putting out 15 volts. Per manual, removed field terminal and the generator dropped off line. Regulator ground good so just determined bad new regulator. Got another one and same thing-charging 15+ volts and drops off line when field wire is pulled...... Have I lost you yet? Anyway, after troubleshooting I found that the field terminal on the generator itself is now grounded.
So, 2 questions- The field post should not be grounded, correct? And #2, did we (I) trash the generator by not polarizing the regulator before starting it?
As you can imagine I wanted to type this differently saying he screwed up. But---
Thanks
Jeff

[fishnjim]

I guess I don't follow your description?
If it's charging and putting out 15 Vs, it's working OK.  Don't mess with it.
You only need to polarize, if not out-putting.
Suggest you take to your local auto-electric shop and get a second opinion.

ps: there's lethal amperage on those wires, so be careful what you do.

[Jeff Rosansky CLC #28373]

Yah, I agree I was wordy. I just wanted to get the chain of events in here to help diagnose what is going on.
Basically I have 15+ volts at about 12-1300 rpm with a fully charged battery. That seems high.
Thanks for the amperage warning. Appreciate it. We have kept that in mind.
Jeff

[Jon S]

 I would expect 13.8 to a max of 14.7 Volts

[PHIL WHYTE CLC 14192]

Sounds like the voltage regulator needs adjusting.

[Jeff Rosansky CLC #28373]

Yes. But I put on 2 brand new units and got the exact same problem.  Regulator ground is good. When the 1st regulator was bad, I grounded the field terminal and the generator came on line. Logically that makes me think that the field terminal isn't always grounded because if it was, then grounding it again would make no difference.  Now, the field terminal is grounded all the time.
With the regulator disconnected, should I get ground at the field terminal?
Thanks
Jeff

[savemy67]

Hello Jeff,

Back in the day, my research indicated that any DC generator should be polarized before engine start if any or all the charging system connections (battery, regulator, generator) were disconnected.  Failure to do so would most likely result in a damaged or destroyed regulator.

One of my troubleshooting diagrams indicates that if grounding the (F)ield terminal of the generator causes generator output to increase to a high value (near 14.3 or more volts for a '55), then the regulator is defective.

If you installed two new regulators, and did not polarize the generator both times, then it is possible you damaged both regulators.  Polarization is done with all connections in place, but before engine start.  A momentary short is made between the BAT and GEN terminals of the regulator.  This provides a surge of current from the battery to the generator so the generator orients north/south relative to the battery.

I think it is more likely to have damaged the regulators than the generator.  You can test the generator in or out of the car to determine if the mechanical/electrical function of the generator is OK.  There are different ways to do this.  Essentially you make the generator a motor.  If the generator tests OK, it may be time for a third regulator. 

The F terminal should not be directly grounded during normal operation, but be sure the generator case has a good ground through the mounting brackets to the block.

Respectfully submitted,

Christopher Winter

[PHIL WHYTE CLC 14192]

I usually polarise the generator by running it as a motor with the fan belt off.

[z3skybolt]

Jeff,

You know far more about this stuff than I. But....after having two regulators fail I was able to purchase a quality, made in the USA regulator for my LaSalle.  They have both positive and negative ground regulators. It was pricey as you can see. $70.00 more than the made in China stuff.  There has to be a difference in quality. Mine has worked perfectly for over 1,000 miles. They have 12 volt systems as well.

https://brillman.com/product/6-volt-delco-type-voltage-regulator-premium/

Good luck,

Bob

[Jeff Rosansky CLC #28373]

Apologies if I wasn't clear with my question.
Should I have continuity between the field terminal and ground? If the answer is no, is there anything short of a rebuild that can fix it?
Thanks

[J. Gomez]

Apologies if I wasn't clear with my question.
Should I have continuity between the field terminal and ground? If the answer is no, is there anything short of a rebuild that can fix it?
Thanks

Jeff,

It all depends on how and under what conditions you are checking continuity.

With engine not running, ignition switch in the off position you will see continuity between ground and the “F” terminal on both gen and V/R. The contacts at the V/R voltage and current relays are closed and the voltage relay contact is connected to ground.

If you current drops when you disconnect the “F” at both the gen and the V/R that means the gen is working (no grounds on it) and the V/R is also working but if your charging voltage is high the voltage regulator relay may need to be adjusted.

There should be a procedure on the Service Manual to adjust the voltage regulator relay. 

Although your V/R is new it may have been adjusted on the high end from the factory, it is always a good idea to recheck and tweak for each new installation.   

Good luck…!   

[Lexi]

Further to Jose's comments. I had a new VR on my car, which had operational issues. Physically, it looked the same as the original except when I opened the cap there were no adjusting screws. I spoke to the rebuilder who sold me the unit and he advised to manually adjust the contact points starting with 5000 of an inch increments. While the VR proved faulty, I was disappointed that this repro did not have adjusting screws. Clay/Lexi

[Jeff Rosansky CLC #28373]

Ok, thanks guys. I just wanted to be sure which gremlin I should be chasing.
Yes. There are no screws for easy adjustments here. I figured it may be off but that seemed like more than I expected. And as I got basically the same readings as I did when I grounded the field I just figured something went bad in the generator. That's why I appreciate everything and love this forum. I admit I have never adjusted a regulator before and, although I understand the principles of how they work, they are somewhat of a mystery to me. 

Thanks for the tip on where to look for another one Bob.
Jeff