I need advise on polarizing my rebuilt generator

[Guest ewing]

First I confess this is a 58 Pontiac, but I am thinking that it is 58 GM so you Buick guys can help me here!

So....I have a 58 Pontiac which has a generator light that came on solid, and I decided to rebuild the generator( 80,000 miles on it). So the rebuild shop completed the job and tells me that the armature was 'shot' and replaced. I have reinstalled the generator and referred to my shop manual that tells me to polarize the generator by momentarily connecting a jumper wire between the BAT and GEN terminals.

I have done that and get no charging indicated ( red light stays on). Basically this is running the + side of the battery to the armature.

Now I have read some how to directions on line and see the advise on the old GM cars is to connect the '[Field' terminal to the Batt terminal on the regulator. Basically this is running the + side of the battery to the field coils....That is the opposite of the manual instruction.

So I plan to try this, ( Field to BATT terminals) to see if that works.

But I have to admit that I am electrically challenged. !

Does anyone have recent experience with this and can advise me which way is correct?

Thanks,

john

[1957buickjim]

John,

Do you have a wiring diagram in the chassis shop manual for your car? That would give you the proper color wires to the proper terminals. Also, when you tried to polarize the generator, you momentarily short out the BAT and GEN terminals on your voltage regulator. Is that what you did?

On my 57 Buick (the same for 58) there is a 10ga. white wire that goes from the A terminal on the gen to the GEN terminal on the voltage regulator. There is a 16ga pink wire that goes from the F term on the gen to the F terminal on the voltage regulator. There is a 14ga yellow wire that goes from ground to ground on the voltage regulator. That is how mine is set up. Hope this helps you in getting the car back on its feet again.

[Guest ewing]

thanks for the feedback Jim.

I did jump the BAT to GEN terminals on the voltage regulator.

I put all the original wiring back where it came from, so unless a wire has broken that should be ok.

Basically jumping the BAT to GEN , I am putting a +ve pole from the battery on the armature.

I have another reference ( albeit from the web and who knows what is right there!), where it is stated that I should connect a jumper from the F (field terminal on the regulator) and touch the BATT terminal). This would put the +ve pole from the battery on the field coils.

This is basically opposite of what the maunal says to do.

I am assuming that the generator is ok, and will produce current when I get the polarity right.

So, I think I will try the reverse polarity to what I have now.... What do you think? That won't hurt anything electrical will it?

[old-tank]

John

My 55 book says to bridge BAT and GEN terminals before starting. That is what the book says, but in reality I have swapped generators and voltage regulators in my shop and on the road without any polarization and it usually worked fine. If it did not work the polarization procedure NEVER solved the problem. The place that rebuilt the generator already polarized it as part of the test procedure. Look elsewhere for the problem, like the voltage regulator; check voltage at the battery before or after starting.

Willie

[1957buickjim]

John,

Another thing to check is that the generator is acutally producing electricity. If you have a multimeter that can be set to 0 - 20v, take the red lead and touch the GEN terminal on your voltage regulator, and touch the black lead to ground with the car running. That will show you if your generator is working properly. Should be in the range of 13.4 - 14.1 volts or so on the meter.

It might also be in your voltge regulator as well. There are a couple of checks you can do on that, with the multi-meter. Test the voltage going to the battery by taking the red lead and putting it on the BAT term on the voltage regulator, and black to ground. That should show you if the charge is getting to the battery. Should be the same range, give or take a few points.

Those will pretty much tell you that your gen is working or that your voltage regulator is working. I have rebuilt 2 generators and both have turned out ok from a working stand point. The usual thing that I have encountered is the burshes are worn down, or the commutator bearing goes bad through lack of lubrication (little oil whole on back of generator). Hope this helps pinpoint your issues. Keep us posted. Thanks.

[wmsue]

Don't remember where I learned it from.....but I can recall jumping Field to Ground to polarize a generator.

[Joseph P. Indusi]

Hook up a voltmeter to the generator, red voltmeter lead to the gen terminal, black voltmeter to a good ground or the battery negative post. Run a jumper from the field or F terminal on the regulator to a good ground. Start the engine and rev it only to 1500 or 2000 RPM. The voltmeter should read above 13.5 to maybe 14.5 volts. If it does not, most likely the generator or the wiring is at fault. If it does read the voltage range above, then disconnect the jumper from F to ground. If the voltage drops then regulator or associated wiring is at fault.

Good luck.

Joe , BCA 33493

[Guest ewing]

Thanks Joe, and all,.... I'll see what gives with these 'checks' and let you know what I find. Thanks.

In the mean time what I do know is that with the car ign on, car running, I get:

13 v at the BATT on the regulator

about 1 v at either the A or F terminal of the generator, and it goes up to about 2 v when I rev up the engine.

I will run again and put a jumper on the F to ground on the regulator to see if the generator output goes up to the 13.5 to 14.5 v range.

If it does go up, joe that would mean the regulator and associated wiring is at fault.?

I can then verify that the generator is ok if the jumper on the regulator from the F to grd results in the gen reading 13.5 to 14.5 v

Hope I have that right.

I'll let you know how I make out.

Edited June 8, 2012 by ewing (see edit history)

[avgwarhawk]

I suspect the generator is working and the regulator is at fault:

A voltage regulator is designed to limit the voltage output of an alternator to 14.5 volts or less to protect the vehicle's electrical system. If the regulator malfunctions and allows uncontrolled voltage to be released, you will see bulbs and other electrical components begin to fail. This is a dangerous and potentially costly problem. Fortunately, this type of failure is very rare. Most failures cause a reduction of voltage or amperage.

[Guest ewing]

based on the testing advise... I get 13.5 v on the generator when I put a jumper from the F to ground. and, about 1 v when I take the jumper off.

I checked all the grounds and they are good.

I checked the continuity of the wires to the generator and they are good.

So I think that leads me to the regulator as the problem.

The shop guy tells me they can put my generator and regulator on the bench and do the adjustments for me on the regulator.

I see the manual gives me directions to adjust the regulator ( on the car)..

What would you guys say? should I try regulator adjustments? Get a new regulator, or take it all to the shop.

Taking all to the shop is messy, as my power steering pump is on the back of the generator. ( but I can do it again, if that makes the most sense.)

What do you think?

[Joseph P. Indusi]

If it were my car I would get a replacement regulator. I understand that NAPA still stocks these old mechanical regulators for generator equipped cars.

Joe

[Guest ewing]

I got a NOS regulator, installed it today, crossed my fingers and fired it up. Everything is working great!

I think I learned a few things along the way too. Thanks for all the good advise and help!

I'm on the road again!

[avgwarhawk]

Good deal. Happy motoring!

[wmsue]

Glad it all worked out.

Have fun driving it.