All,
I am having an issue with the voltage regulator on my '58 3200 with a 235. I have tried two good quality made in the USA replacement regulators from two different manufacturers and they both have the same issue.
The Cutout relay is not working properly. I cannot seem to get it to work reliably. Either I have it fail to activate and so I don't get any charging of the battery or it won't open and the battery drains through the generator after stopping the truck.
My diagnosis steps are the following.
First I disconnected the generator and grounded the field to the frame. I ran the truck and measured the voltage at the armature post on the generator. The voltage was about 12v at idle and increased linearly with the RPM of the engine up to about 65 volts. When I rebuilt the generator I bench tested it by running it as a motor and measuring the current draw. I don't recall the number, but it was within tolerance (I think 7 amps).
Next, I checked all of the wiring. I checked for shorts in the wires as well as touching wires. I checked the engine ground, field wire from generator to regulator, armature wire from generator to regulator, charge wire from regulator to ammeter and charge wire from ammeter to positive post on the starter. All wires are good. No shorts to ground and no wires shorting to each other. I connected and triple checked the connections.
Then, I checked that the regulator is properly grounded. I checked continuity between the regulator base, the generator frame, the engine and the negative battery post. All grounding checked out and I double checked all the connections.
I verified that the generator and regulator are working to regulate the voltage by measuring the voltage at the armature post on the regulator while the truck is running. At idle I have around 13 volts and it rises to 14.2 volts at high rpm.
I consistently have battery voltage at the BATT terminal of the voltage regulator. I pulled the cover off the regulator and manually engaged the cutout relay and the BATT terminal went up to the armature voltage and the battery began to charge. After restarting the truck the cutout relay again failed to engage and the truck wouldn't charge.
Neither of the regulators are adjustable. So, I bent the tab for the spring on the cutout relay to decrease spring tension. I moved it only a tiny bit and the relay began to engage. But, when I stopped the truck the cutout failed to disengage and allowed current to flow through to the generator and discharge the battery.
No matter how small of an adjustment I made I could not get the cutout relay to work reliably. It either failed to engage or failed to disengage. I followed the service manual instructions for heating up the regulator by running it for a while and then cycling the points.
At this point I am stumped. I don't think two different regulators from two different manufactures would fail in exactly the same way. It makes me think that something external is causing the failure, but I don't know what that could be.
My next step just to get the truck running is to install a large diode in the line to prevent discharging through the generator when the truck is stopped. But, I would like to find the culprit here and fix the problem.
Thank,
Chad
