Alternator Overcharge

[n3w6uy]

I had been in and out of my 73 Valiant 225 all day yesterday running errands and on my way home i start my car and notice my dash lights are VERY bright and my alternator guage is maxed out above 40+ if I have any kind of acceleration going on. If its idleing, the guage reads straight up, but any increase in RPM and the guge shoots all the way up. What could be the cause?

 

[69Dartconvt69]

On the back of the engine there is a plug at the firewall, pull it apart and check for corrosion. If it's corroded, clean it and that should solve your problem. Also check your battery for a bad cell, this can cause the regulator to see a low battery condition.

It also could be your regulator but check the other two things first before you start replacing parts. I've watched "mechanics" replace everything in a case like yours and still have the same problem, you can spend a couple hundred $ and find out it may have cost you some time only.

Let me know what you find.

 

[damnimcooltom]

Or one of your field wires could have worn through due to vibration and is grounding out, causing the alternator to put out 100%. Or the alternator itself could have had an internal issue causing the same issue. You might want to pull the brushes and clean them up or replace them. Don't lose or forget to reinstall the insulating washers, or you'll be causing the same problem.

 

[cudajim]

I'd start by unplugging the regulator. It sounds like it's not regulating the field of the alternator or, as previously stated above, you have a ground path on the regulated side of the field winding. The other side of the field .should be connected to a positive supply. In any case, don't run it for long until you fix it or you will fry your battery or worse.

 

[n3w6uy]

Fixed it, it was the regulator. Local autoparts stores can have it in about a week; man I love having spare slanted A's laying around

Thanks everyone for your help, this is why I love FABO!