80 sc laternator problem
 

I have a 80 sc with an alternator problem I have been trying to correct. Some months ago I had the internal voltgage regulator go bad and with help from this board I took the alternator out , replaced the regulator, and then had an alternator shop check it out to make sure everything was ok before reinstalling it. It was fine for awhile but then I began to get a very faint red light on the dash after starting and running. I charged the battery and then reinstalled. Still have the faint light. Battery voltgage is 12.75 volts sitting in the driveway. When I run the engine at 2000 rpm the faaint light becomes a little more noticeable. Before removing the alternator again, am I missing something? Thanks for the help.

Fan belt tension right? Less than a half inch deflection. Could be a bad VR but before you remove it again, make sure you have the belt tight. YMMV

+1 on the fan belt.

Did you put the shims back as they were?

Also,

What is your battery voltage with the engine running?

It should be 13.5-14.5V

A bad VR normally increases the above numbers, and eventually cooks the battery.

Loose connection at the alternator?

Bad re-build?

Good luck,

Gerry

you need to measure the voltage both at idle and running.

If youre getting erratic voltage, too low, then high, etc, probably the VR. If you're getting only 12.75 with no fluctuation, alternator is bad.

I have had this symtom happen to me, where the red light would appear & get brighter with more rpm.
It was none other than the VR.
Somethin failed within its internal diode or somethin like that.
(sadly, not all new components are 100%)