1982 f 150 inline six . 4 speed manual . alternator is charging battery at 16.8 volts while i am drivng . with hi beams and blower on high . sound like a voltage regulator ? battery is new and alternator has new brushes and bearings . with no headlights and blower off , iy charges over 17 volts . if i let it sit for a day or two . theres not enough juice in the battery to even turn her over . I took the field wire off the alternator and it stopped discharging . It also won't charge the battery with the field disconnected . Is it possible that the diodes in the alternator are damaged ?

 

Yes, it is very likely the alternator's diodes are toast. But the regulator surely is as well. You need to fix it ASAP or there will be other problems as well.

 

thank you . are diodes something i can pick up and replace or is a new alternator the way to go ?

 

As I'm rebuilding an alternator at present, I'd say get a rebuilt one. I'm going to have more in mine than a rebuilt would cost. Your local parts store can test yours and sell you another if it is bad.

 

Most parts stores will only check output.
Check for backflow yourself if you have a multimeter with diode test.
Just ohming it out often won't put enough current to the diode. (depending on your meter)

A regulator is cheap, but check first to make sure yours is getting 'sense' voltage from the system.
Could be a broken wire or a corroded plug if your regulator is that style.

 

Not sure which alternator you have, if it's the 1G or 2G. But I just bought a rebuild kit for mine and a new slip ring for $35. New brushes, holder, springs, new HD rectifier, new slip ring, new voltage regulator. Local parts store wants $70 for a china reman 2G... I'll do it myself and do a better job at it than they do. Sounds like yours is pretty messed up.

Edit: noticed yours is an 82, so it should be a 1G. 86 was the first year for the internally regulated 2G fire hazard.

 

yup . External regulator . Have a Motorcraft regulator coming in a few days . That should solve the overcharging deal . I had a guy put new brushes an d bearings in the old alternator , still may need to replace the diode trio . We'll see . One thing at a time !

 

If it is discharging through the alternator you need the diodes.

 

Don't run an alternator with problems on a new regulator as you are likely to fry the new regulator.

 

New diode bridges are cheap on Ebay. Just type in Ford 1G alternator diodes and you should see it come up.

 

I agree with the last 3 posts . I checked on diodes and they're only a few dollars . I'll replace them before the new reg goes in . Thanks .