<VV> Re: hot voltge problem

[djtcz at comcast.net]

> Subject: Voltage Failure Heat-Related 
> 
> A few weeks back I asked for help with a voltage drop in my '63 with '70s-style 
> alternator. Many thanks to those of you who replied. 
> 
> The problem hasn't gone away, despite a lot of troubleshooting. In fact, it's  gotten worse! 
> 
> At idle the alternator produces 14.6 volts, measured at the alt or the battery  posts. In the driveway, raising the RPM produces a very slight rise in voltage. 
> 
> But the car will only go a few blocks in the heat until voltage trails off to 
> the point it will no longer power the ignition. The voltage drop also increases  with RPM. 
> 
> Here's a list of things I've replaced: 
> 
> - internal regulator 
> - alternator 
> - battery 
> - slotted belt 
> - new wrapped belt (some temporary improvement) 
> - spring-loaded pulley (some temporary improvement) 
> 
> I've cleaned the terminals at the battery and starter, where the alt wire links up to the battery cable leading to the trunk-mounted battery. Also checked the  battery and engine grounds, and jumpered around the engine ground as an  experiment - no change. 
> 
> I did super-tighten the belt as an experiment and got improvement, but couldn't  leave it that way out of concern for the blower bearing. 
> 
> Obviously I've missed something. Heat is a definite factor - the car drives  fine in the winter months. 
> 

Can you run it for a while in the driveway and make it happen? The voltage at the battery drops when things get warm? How is the battery grounded in the trunk?  I'd probably start by provoking the problem, then run a good quality jumper cable from bat ground terminal  to  front bumper, then back to frame then engine direct.  A volte meter might help taking readings from front to back,