I've daily driving her for awhile. Alternator quit charging. Simple, change the alt. Used a spare I had. Charging fine, on multimeter. Gauge in car is not accurate. Get to work, it's over charging. Bad voltage regulator? That was my thought. Bought a new one. Smelt hot and slowly increased to higher voltage. Exchanged it. Hooked up the new one. Charging great. Drive it 15 miles. Still great. Another 15 and it's charging at 16.5 again. Tried 2 new battery, grounds are clean. My gas gauge started working in the middle of this scenario and stopped again. My a/c quit working sometime ago. I can jump power to it and it turns on. Any opinions on this would be great. I'm racking my brain around this. Is it safe to say I got another bad alternator? Or do I have something thats causing over charge? It slowly increases voltage output

Is the regulator separate from the alternator in those years / models?  I skipped from a 78 to a 86, so I don't know.  Anyway, overcharge would be a regulator problem, whether it's internal to the alternator or external.

Double check the chassis, engine, and alternator grounds.

Mine is internally regulated. Grounds are clean and seem to be working correctly. Maybe I am just working with another bad alternator

Mine is internally regulated. Grounds are clean and seem to be working correctly. Maybe I am just working with another bad alternator

Check the Black/white wire at the 2 prong connector.  If it is not getting 12v from IG. switch, or is a poor connection, it could be making the Alt try like hell to raise the voltage with no effect.

 

Also, It may be a good idea to replace/add a new 10 or 8 gauge wire straight from the Main output terminal on alt to the Battery (using a 1~2 inch long piece of 8 gauge Fusible link wire at the batt end)

I'll check that out. I don't believe I have checked that. It is hooked to the output power. I know I'm getting full power at the end of the output wire. The white with red goes to the gauge, and that doesn't always show correct voltage. Has been different reading with all alternator.

Check battery as well while you’re doing all this. Could a battery with internal issues help cause this?

Edited November 6, 20178 yr by idosubaru

I thought maybe a battery issue. But I have tried 2 new batteries causing the same reaction. I may just change the wiring to my alternator and see if that makes a difference.

I thought maybe a battery issue. But I have tried 2 new batteries causing the same reaction. I may just change the wiring to my alternator and see if that makes a difference.

white/red goes to "charge " light, not the gauge.