67 charging issue

[67440NewYorker]

Got my car running a few days ago. Been doing great until tonight im cruising and my volt guage is around 12.5V. I get it home and put my tester on it and verify my guage is correct. I rev the car up and it goes up to 12.7V. Im suspecting my voltage regulator but i know nothing about these old ones.

 

[Big_John]

Here's how you test it.

Take a voltage reading at the battery just for reference, car not running.

Disconnect the green wire from the alternator and make a jumper wire that goes from the connector on the alternator to (EDIT) the output post on the alternator.

Turn on the headlights on high beam and start the car.

Check the voltage at the battery again. It should be 14-15 volts at minimum. If it's not, there's a problem with the alternator. If there is, the problem is either the voltage regulator or the wiring to the VR.

Don't run the car for long like this. Just long enough to check voltage.

This duplicates the FSM procedure except you are using the headlights to load the battery rather than the carbon pile. What we are doing is bypassing the VR to perform the test. The VR controls the alternator by completing the circuit in the field to positive 12 volts.

 

[67440NewYorker]

Just did the test and it started out at 12.72v with nothing on. Started the car with highbeams on and dropped to 12.25V. I unhooked the green wire and ran a jumper right to the negative on the battery

 

[Ross Wooldridge]

Alternator.

 

[67440NewYorker]

Alternator.

Thanks for the advice! It was charging great when I went for a cruise and noticed a problem when my blinkers were on. At least I made it home before dark! Car hasnt been on the road in about 3yrs and I have been cruising it every night since I got the engine back in!

 

['66 Fury I]

Pic in post#1 looks like the old pre electronic regulator. If so there should be only one field terminal on the alternator. The other brush is grounded. If this is the case, I believe the test should be to remove the wire from the field terminal at the alternator and supply battery voltage to it and complete the test a Big John suggested. Lindsay

 

[413]

Yes you put 12 volts to the green field wire, grounding the green wire will do nothing.

 

[Big_John]

Guys I screwed up and wrote to connect the wire to ground. I meant to the positive terminal.

No excuse... I'll edited my post and I apologize for any confusion, especially to @67440NewYorker who did the work.

Connecting to ground for the later (70 and up) is the correct way, but earlier cars, with the single field connection connects to positive.

 

[67440NewYorker]

Pic in post#1 looks like the old pre electronic regulator. If so there should be only one field terminal on the alternator. The other brush is grounded. If this is the case, I believe the test should be to remove the wire from the field terminal at the alternator and supply battery voltage to it and complete the test a Big John suggested. Lindsay

I will do this tonight and post my results. Thanks!

 

[67440NewYorker]

Guys I screwed up and wrote to connect the wire to ground. I meant to the positive terminal.

No excuse... I'll edited my post and I apologize for any confusion, especially to @67440NewYorker who did the work.

Connecting to ground for the later (70 and up) is the correct way, but earlier cars, with the single field connection connects to positive.

I unhooked the green (field) wire and hooked it to the positive terminal with lights on. And with running a little off idle.

 

[67440NewYorker]

Guys I screwed up and wrote to connect the wire to ground. I meant to the positive terminal.

No excuse... I'll edited my post and I apologize for any confusion, especially to @67440NewYorker who did the work.

Connecting to ground for the later (70 and up) is the correct way, but earlier cars, with the single field connection connects

I unhooked the green (field) wire and hooked it to the positive terminal with lights on. And with running a little off idle.

View attachment 612830

I ordered a newer alternator as they cant find one for this car and im gonna wire in a newer electronic voltage regulator for it as I have those parts on the shelf. I guess I should modernize it a little bit while im at it.

 

[413]

Just take the dual field alternator and ground one terminal and put the car. No reason to change anything.