Voltage Regulator problem

70 Challenger RT.
The Voltage regulator is dripping a resin type substance from the back. It is running down the firewall, and making a mess.
This happened with the last one, so I replaced it thinking it was defective. Now it is happening again with the second one. Both new, original type regulators.
I noticed it last night after a 20 minute drive. Using laser temp gun, the firewall was about 105 degrees, the regulator was about 130 degrees.
Any guidance is appreciated.
Mike

My theory is they aren't getting a good ground, and over heating melting the rein. They are case grounded by the case screws to the firewall. What I did was to scrape a little paint off the back at the bolt holes, and the same on the fire wall, then after I installed it, I took the plastic air screen off the cowl, and put toothed washers that would dig into the metal, with self locking nuts.

71birdJ68,
Thanks for the tip.
That sounds plausible. I will try that and post back.
My thoughts would be:
alternator putting out excessive voltage.
another wiring issue somewhere.

Anyway, I'll modify the mounts and see how that will work.

Anybody know if the Voltage regulator runs a hotter temp than surrounding firewall? If so what would be normal?
Thanks.

The alt wouldn't have anything to do with it. I can't remember the correct terms here, so bear with me. The reg looks at the voltage from inside the car, which what one of its wires are for, and tells the alt what to do with the other wire. It also looks at under hood temps. If you have bad connections, or corrosion in the connections it could see less than 12 volts, and tell the alt to charge more than needed.
I think you would have better luck getting responses with questions like this if you posted over in the question and answer section, cause a lot of those guys don't bother with restoration stuff.

Yes.
Here's a crude diagram of the regulator wiring.
Blue wire provides electricity to the Alternator's field windings (the ones the spin) AND
Blue wire also goes to the Voltage Regulator to indicate system voltage.

Green Wire is the outlet for the field windings. It goes to ground through the Regulator. The regulator controls power by the amount of current allowed to flow to ground.

Here is the same diagram with the switch closed.
Everything with yellow is system voltage.
With the switch on, but engine not running, some current current flows through the field. If the battery is 12.5 Volts, the blue wire will be close to 12.5 Volts. The green wire will be less because power is used by the windings generating the magnetic currrent.

If the engine was running, the ammeter would be centered (or show charging if the battery needed charging). The system voltage would be 14 Volts more or less, and would come from the alternator output (Bat) stud. The blue wire would be the same. The green wire would be noticibly less than 14 Volts if current was flowing (when power is needed), and 14 Volts if no power was needed.

The regulator grounds through the bolts to the firewall. The toothed washers help greatly.

Scraping the paint off is helping nothing and asking for problems later from the rust that will form. Auto manufacturers have been grounding items to the body for decades, they never scrape the paint off. Un necessary waste of time folks.

I disagree

Well, its not too hard to check if there is a ground problem. When the alternator is running, measure voltage difference between the Battery Negative and the Regulator body. Then check the mounting bolt and the body if there's a measureable difference.

While at it, measure the voltage difference between the blue wire and the regulator body. This is the voltage difference which determines how much current the regulator will let through the field. Lets say it is low due to poor grounds or poor connection on the feed. Either way, it might result in the regulator trying to max the field and eventually overheat itself. Just a possibility.

The easy way; I run a separate wire from the head to all items on the firewall needing a good ground, not like the factory, but effective.

My 2 cents.

Joe