57 Bird - gen lite brightens with RPM

[cscolastico]

I was on my way home Saturday night from a car show when just about a mile or so from home my gen light came on at a stop. It normally flickers a bit but this was a steady dim illumination. The odd part is that when I increased the RPMs, the gen light brightened and then would go dim when back to idle. The next day I tried to trouble shoot but the gen light behaved as normal. I checked the voltage at the battery ~12.5, ~13.5 idle and ~14.5 revved up. I've lived long enough to know that these issues rarely go away on their own. I hate intermittent problems. Needless to say, I am hesitant to drive any distance from home without knowing or fixing the problem. I checked the belt and connections Any ideas why the problem would be intermittent -or what it might be? I reviewed the shop manual and was going to do a gen output test but my suspicion is that it will show 14~v just as it did at the battery and would be a waste of time.

Thanks for any help

[1957Birdman]

I have had somewhat the same problem with my car, but it happens when the car is just warming up. I think it is related to the voltage regulator or maybe a wire isn't grounded properly. A friend in out local club adjusted the regulator and that seemed to help. I would try that first unless someone else on the forum has a better idea.
Good luck,
Lew Bachman
1957 Colonial White

[paul2748]

Check all the connections at the regulator and generator. Not just tightness but make sure contact areas are nice an shiney

[cscolastico]

Thanks for the tips guys!

[thessler]

If it were mine I would replace the regulator. Maybe a waste of money but I would just do it for a piece of mind.
Tom

[voltron]

I've seen this scenario a few times in my life that besides the voltage regulator, it was caused by worn brushes in the generator. When worn down the brush spring tension decreases.

[1957Birdman]

That makes sense, but in my case it happened when the generator was just serviced and new brushes were installed. Mine does it now only when the engine is cold. As soon as it warms up for a few minutes the circuit seems to act normally.
Lew Bachman
1957 Colonial White

[cscolastico]

Thanks all for the help. I think I'm going to do generator output test (in car) per the shop manual and if that is normal I'm going to replace the regulator and go from there.