hmartin

Hi, we had the original generator rebuilt on my grandpa's 62 Olds Starfire and now it seems after warming up and driving the battery is weak. I remove the battery cable and it dies. The generator light has also been on as well and the turn signals in the dash and blinkers are not working. Is their anyway to check the charging output of the generator on the car while it is running? I am trying to convince my dad this is the problem, just some info I was born 11 years later after the car was built new!Thanks

MDchanic

Yeah - put a voltmeter on the the output stud and see what the voltage is.

Are you sure it's connected properly?

Are the connections and grounds clean?

Is this a generator or an alternator?

- Eric

hmartin

Eric, I just tried a voltmeter on the A (Armature?) F(Field?). I took the red lead to each terminal while grounding out and no voltage while idling. I also checked the battery and it showed 11.98. When the battery has a full charge it does not load up and runs fairly clean. This wasn't the case earlier, loading up bad while cold and still heavy exhaust fumes after warming up!

hmartin

Sorry, forgot to add this is an original Delco Generator, the car is 62 Starfire without air conditioning. I read this was a change over mid year to alternators. Thanks

MDchanic

I'm no generator expert, but I know that the generator should be putting out some current not too far above idle.

I think you missed one connection on the generator - the big one with the thick wire - that is where you should test.

A voltage of 11.98 at the battery indicated no charging is going on.
Either the generator was put together wrong, it is connected wrong, the connections or grounds are dirty, the regulator is bad, or the belt is REALLY loose.

- Eric

hmartin

Eric I checked the A post which is a larger brown wire with a wire going to the radio condensor and the F post which is a blue wire, pretty sure that is right. Just put a new regulator on, belt seems tight, the only thing we haven't done is put a ground strap on the engine (394) itself. Does that all make any sense? The guy that rebuilt it said that it was in excellent shape for a rebuild which with 82,xxx original miles it should be.

MDchanic

Okay, then the A post should be about 13 volts.

The engine should definitely be grounded, too, either by a strap or wire from the engine to the body, or there should be a heavy wire from the battery to the engine and a lighter wire (about 10ga) from the battery to the body.

Could always be your regulator.

To test, you can hot-field the generator (or at least you can on most cars - as I say, I'm no generator expert - I've done this in the past, but never on a GM) by connecting the F terminal to +12V (disconnecting it from its wire and jumping the terminal to the A post) - the voltage at the A-post should jump up over 15 (only do this for a second).

This should prove the generator good, so you can go on to check other things.

- Eric

rocketraider

Did you polarize the generator after installation?

OK, see Eric already mentioned it. Flash the field by jumpering from 12v+ to the F (field) terminal and see if it starts charging. (I think that's the right way, haven't done this in 40 years).

hmartin

The generator has never been polarized itself since the rebuild! We just replaced the regulator a week ago and followed the instructions sent with the regulator to polarize it. If weather is permitting I will try the polarizing procedure for the generator as well as a suitable ground. I have 3 grounds on my 67 Chevelle, I know this is critical!

stellar

1st the reg does not get polarized. The genny does. MDchanic and Rocket raider give good advise, but it is for ford application. To polarize YOUR GM genny with all wires connected at the gen and reg, you will take a jumper wire and flash the connections at the reg BAT to GEN or it May say Bat and ARM Some regs will have the terminal that comes from the gen A post marked either gen or arm They are one and the same. So if the wires are not connected on the reg you can just touch the bat wire to the gen arm wire for only an instant. Personally I prefer to polarize the gen with the reg wires disconnected, but it can be done either way. Now if you have the reg wires disconnected you can then ground the field wire and you should get output from the Arm wire. Again like Eric said do not do this for very long. At this point, if you get output from the Gen A wire you know the wires and gen are good theoreticaly. Now connect the reg wires and retest. If you still have a no charge condition, I hate to say you may have a bad reg or even a bad gen. Just because the gen puts out when full fielded does not mean it will work properly thru the reg. This is when you should ask the rebuilder if he ran the rebuilt gen thru a reg when it was tested. Unfortunatley the regs being made today are not quite what I think they should be. You may need to have it adjusted by a qualified tech even tho it is new.

MDchanic

Thanks, Stellar, and you're right - I've dealt with VW and '40s F_rd generators, but never with GM.

If I recall, there's usually a big card or sheet of paper with every new or rebuilt generator or alternator that tells you what you need to do to polarize them. It's been a while.

- Eric

hmartin

So will the regulator need adjusted or generator? Sorry guys this type of charging system is new to me, I am trying to learn, thank you for the info

stellar

The reg may need adjusted. The gen will either work right or not. There are no gen adjustments. Have you polarized it and tested for gen A output?

hmartin

Stellar I will put the new ground strap on tomorrow, polarize, and post my results. Hoping to cruise when the weather straightens out soon, thanks for the info. Like I said in the beginning posts I thought polarize new regulator, good to go, didn't know about the generator.

stellar

Take it one step at a time. Don't be sorry. That is why we are here. You can learn a lot here. This olds forum has a lot of good guys. I'm sorry I forgot so much of this older stuff. It takes a minute for it to come back. oldtimers disease I guess. Just kidding. It is still there. If it is new to you don't worry it is a pretty simple system and you will figure it out fast. If not we can walk you thru it.

stellar

If you polarized it with all the wires connected to the reg and gen, then the genny is already polarized. Let us know what happens when you retest. Mark

rocketraider

Actually, Stellar- the last one I did was on a 1954 Farmall Super A tractor!

stellar

Yep thats a ford generator on the farmall. I just had a fellow come to the shop last fall with a generator for one of the old farmalls. 6Volt with the wide pulley about a 1 inch wide belt. He was a bit suprised when I had one on the shelf already rebuilt and ready to go. He was restoring his grandfathers tractor and wanted his rebuilt to keep it original even though it had a chunk broken off the pulley. He had pictures of it now and when he was a child riding it with his grand pap. That is a beautiful machine and they were work horses. I wonder if any of the tractors built today will last 60-70 years and still work good.

hmartin

Well guys even though I had to sewer snake our lateral line at our house it was a good day. I polarized the generator like stellar suggested and what do you know at idle 10volts lowest for just a moment to mostly 13.4-13.8 volts and no more generator light, HURRAY! Battery voltage was also 13.8 idling. I will post a new thread about turn signals and courtesy lights. I want to thank you guys for the help

MDchanic

Thank Mark, he's the expert. My suggestions were ham-handed.

I'm glad you got it, though!

I may be more help with the other questions.

- Eric

stellar

I'll take the show position. I believe Rocketraider and Eric were first to mention polarization, so they get the win and place positions. The winner was hmartin. He bet on all the right horses.

MDchanic

Aw, shucks.

rocketraider

You're welcome. Stellar got you on the right track for a Delco-Remy generator.

And once again the Forum works.