I've got a charging system problem that developed yesterday on the way home from a local cruise-in.

First, a little background info:
I've got 1 7/8" kooks headers, 427 cube motor. Recently I gave the engine compartment some ventilation by cutting the ACI cowl induction hood and opening up the hood liner, but before that under hood temps were high enough to melt some of the wire insulation on the starter wires.

Yesterday, I started it up and headed out. The dash gage read normal charging voltage. About a half mile from my destination, I noticed the the alternator had stopped charging, and the voltage was reading less than eleven volts.

The car started when I was about to leave, but the voltage was now ten volts and dropping fast. It was still daylight, so no lights were on other than the daytime running lights. However, my car does draw significantly, with a high volume fuel pump, an electric water pump, and of course everything else electrical that makes the car run. On the trip home, the voltage dropped like a rock, and a block away from home the gages died and the car started to miss. I just about made it into the driveway.

Before I shut it off, I checked the voltage at the battery, which was less than eight, although the alternator was at fifteen volts at the hot post.

Today, I checked the starter wires, and tightened up the nut on the lug that supplies voltage directly to the starter motor from the solenoid. The other wires were tight, although the insulation was looking a bit melted.

I bought a new battery today (it was due anyway), and took a test drive and got some fuel.

It was charging fine on the way to the gas station, but when I started it up to drive home, the "charge system fault" warning came on, and again it stopped showing a charge on the dash gage with about eleven volts.

This time, when I home, I checked the battery voltage with the car still running, and it read about about 10 1/2 volts. The alternator however, read zero this time.

I shut the car off, and again read the voltage, which still showed about ten volts or so at the battery, but zero at the alternator.

These are my inexpert conclusions, so someone (Bill?) please correct me if I'm way off base:

1) There was a break (melted, burned, something obviously) in the main lead connecting the battery and the alternator.

2) As a result, the car ran the alternator wide open and thus it has now burned up too

3) Now I have to take the header off, take the starter off, and track down each wire until I find where it's NG.

4) Also, I have to take off the alternator and have it rebuilt

I'd love to hear some thoughts from those out there who may have experience this, and thanks ahead for anyone who takes the time to write some possibilities

 

Bill

As per your PM, Im responding to your post. The POSITIVE connection on the battery should be 100% intact with the connection on the back of the alternator. With the engine OFF, read the VOLTAGE to ground at the battery POS terminal and then at the alternator terminal. Post your results. They should be the SAME.

Disconnect the battery and read the the resistance between the connections from alternator to positive battery cable. You should see very close to zero ohms. Heat does strange things to wires and wiring connections. If you see much more than a couple of ohm of resistance, you will need to find the high resistance connection and fix it.

Each of those wires has an inline FUSEABLE LINK in series with the wire. Thay can deteroriate and cause high resistance.

 

Bill,
Thanks for posting. Evidently, either the fusible link blew because of a short, or the wire simply got cooked until it snapped, since there was zero volts at the alternator hot lead when the battery was good. This should be an easy fix. Thanks again for taking the time to reply.

 

Once you understand that circuit,,,its fairly easy to troubleshoot.

BC