My 87 NA show 14 volts on the gauge when the engine is cold but after driving a while it falls to just above 12 volts. Consequently, my battery is not charging well. The battery is only about a year old and alternator belt is adjusted right. I tried to read the voltage from the 2 prong connector on the back of the alternator per the factory manual but couldn't get the probe in without grounding against the alternator casing.

Any suggestions on where to start looking?

Thanks.

 

Take your alt and have it tested. Most places test for free...

 

Your Stator Winding Insulation is shot. Get it tested and replace it

 

Could this be underdrive pulleys?

The guy who owned the car before myself put those on and it is screwing me up. When the engine is cold it idles at 1500, and is charging normal, but when the engine is warm and idles at 800 the charge drops. I am pretty sure that this is the cause because when I am driving it, or I just rev it up, the volts go back to normal.

Has anyone confirm this or has ever heard of such a thing?

 

thats a distinct possibility, I have seen it before. But the only way to be sure is to have the alt. tested.

Jarrett

 

Your alternator is dying. The underdrive pullies are simply making the problem more apparent. Replace the alternator.

 

if it has pulleys already on it then it's normal to go down to 12 when warm at night, when at a red light for example (headlights and brake lights sap a lotta power). I have it on my car too w/ my UR pulleys and a brand new alternator. FD alternator is the solution, 70 amps for these cars is barely enough for stock let alone a car w/ pulleys.

 

for about 4 days, mine was like that, then suddenly my car wouldn't start unless I push started it, and the electronics started messing up... radio would trun on and off whenever, tach jumped around, etc. then I replaced my alt. with one I had lying around, and problem fixed!!!!!