93 ATX almost loses electrical power after two miles

[TwistedD85]

The 93 was fine just yesterday, but this morning I was taking it out and about a half mile to a mile from the house I had to turn around and come back because the car was losing power, electrical power. It was the morning so it was just regular driving and the headlights. But after waiting for the rain to stop I went out to see how it was and checked the battery with a multimeter, it says around 12.3v. So I turned the key and everything started just fine, I was thinking the alternator, but I thought a bad alternator would leave the battery sapped for power, especially after I could barely get the window up after coming back this morning. I'm going outside now to do some more tests before the rest of the rain comes, but any thoughts on this or methods of testing whether it's the alternator or battery would be of great help.

:thankyou:

 

[TwistedD85]

Update: Tested the battery voltages under load and I got the following.

11.91v at idle with no accessories on, just the hood lamp.
11.66v under load with headlights on bright and revving the engine up to around 2-2.5k
12.05v in small bursts when I first revved it to test and sometimes while idling or sustaining an RPM, it kind of 'leaps' a hundred RPMs or so and gives me over 12v

I also pulled out my stethoscope and placed it to the alternator housing, while I'm sure I'm picking up the squeaky idler pulley nearby to a point it still sounds like a different kind of grinding than the pulley's putting out or so I want to believe. Also the battery's voltage rarely fluctuates once it reaches the voltages above, it simply stays at those until I change the load, it's very consistent and it starts strong. So at this point I'm thinking alternator bearings?

Oh and the battery has no corrosion, for once, the grease works! :woo-hoo:

 

[93markVIII]

the bearings might be bad and loud/squeaky/grindy, but thats not why the alternator isn't charging.

you need a new alternator. or to have yours rebuilt. (voltage regulator and brushes are common failure points.)

 

[TwistedD85]

I'm gonna get to keep this alternator once I swap it out, so I'm going to look around and brush up on rebuilding it, maybe get to keep it as a spare and learn a little something. Thanks for the help :thankyou: