Electrical: Melting wires, smoke signals, Avanti

[tluz]

If this were an E-Type Jaguar with Lucas electricals I would shrug and assume it's all normal. Except of course that it might burn down my garage.

Here's the scenario; any input you guys have is welcome.

The car: 1963 Avanti R-1, original Stude engine (rebuilt), new Remy/Nippondenso alternator from Rock Auto wired per instructions on Bob Johnstone's web site. New wiring harness from Studebakers West. Dave T-Bow Chrysler electronic ignition.

Background: Car was a non-running basket case restored over 5 years. This summer we finally got it running. This fall I was able to drive it short distances and commenced troubleshooting the many items I *ahem* screwed up. It has started nicely more than a dozen times and has a nice idle. Needs a choke adjustment and other fixes to prevent stalling, but I digress.

The Problem: I hadn't started the car for a few weeks because there was always something more urgent to deal with. Last night I had some time and tried to fire her up. Primed the carb with a little 93 octane and it turned over nice and hard, coughed a few times but did not catch. Tried a few more times and flooded the carburetor. Came back later and still could not get it running. Eventually the battery started to fade and I gave up. I charged the battery and vowed to return to the fight today.

This morning I turned the key and nothing happened. No click, no crank, complete silence.

Hmmm, says I. I put a test light on the battery and got a nice, bright light. Then I saw the melted wire. The white ground wire from the voltage regulator case to the harness had been fried so hot that it melted and broke. This is strange for a couple of reasons. First, the voltage regulator is ornamental at this point because the new alternator is internally regulated and the wires that went to the VR have been reassigned. Second, what would cause a ground wire to melt?

Please note that at all relevant times today the ignition switch was OFF.

I reconstructed the experiment with a new ground wire and accomplished the same result within seconds of reconnecting the battery. Lots of smoke and melted insulation. I didn't wait for the copper to melt this time; I disconnected the power and cogitated. The ignition switch is off, yet there is power running through to the voltage regulator harness ground.

Hmmm, says I again. I ran a new ground, this time not from the harness, but straight to the chassis. 8 gauge solid copper wire. I reconnected the battery and no smoke came from the new ground. Instead, smoke started coming out from under the dash and in the vicinity of the starter solenoid. I disconnected the battery again, checked under the dash and found that the red insulation on the wire from the output terminal of the ammeter to the input side of the solenoid had melted and bubbled. So the short, if that's what it was, migrated. Battery disconnected and more thinking.

Well this is unusual, I think to my self. I draw a wiring diagram of the affected parts and consulted with my friend Jim, whose disease manifests itself in the form of Porsches and spec Miatas, not Studes, but who generally can think things through pretty well. He focused on what could have happened between last night and this morning, and wondered about mice, but was pretty much flummoxed.

I suppose I'll have to start analyzing each connection but would rather not fry too many more wires before I figure out what's going on.

My first unconfirmed suspicion is that there's a short in the harness somewhere. My second unconfirmed suspicion is that the bypassing of the voltage regulator while still using its battery and ignition posts has caused some unanticipated short.

How would you fellows approach this and what would you look at first?

Many thanks,

Tom

[bezhawk]

The red wire to the ammeter comes from the starter solenoid, and the + battery post terminal. It is the heavy terminal opposite the other heavy terminal that goes to the starter cable. Are you sure the melted wire was a PLAIN white wire, and NOT the one with the red tracer stripe?

[tluz]

Yes, positive it was a white, and confirmed on the location of the ammeter wire. The white with red is intact and runs to the Bat terminal on the VR. This wire is always hot with the engine on, running from the B post on the alternator through a 60 amp fuse to the VR.

[brian6373]

As you probably already know, you are getting a direct path to ground in a circuit that is energized when the battery is hooked up. My question would be: where is the power to the VR coming from? If you are using the pos. batt. post on the starter solenoid as a power terminal for other wires try disconnecting all of them, then touch the positive battery cable to the battery terminal and see if there is an arc. if there is no arc connect the battery and take each wire that was on the starter solenoid and touch each one at a time to the solenoid batt. terminal until you get an arc. This will tell you which circuit is grounded and go from there to eliminate possibilities. With a D.C. circuit your power will only go to ground after it has passed through a "load" be it a light , motor, or other device. If I had to guess I would disconnect the hot lead from the VR and see if that is the problem.

[tluz]

Thanks, Brian. Clearly explained and logical. This will be today's project.

[Rerun]

Tom, We are looking forward to seeing you and the Avanti at York, so lets get this straightened out. My guess is that when you were doing the cranking, the tips of the solenoid welded together, creating a high resistance path to the starter, even with the key off. The starter bendix would still be engaged in the flywheel. When the battery was re-connected, there would be voltage at the starter lug, but not enough current to turn the starter. There would be an additional path back through the ammeter, to the battery, with enough current to smoke the white and/or red wires. Remove one of the cables from the solenoid, and check for any continuity between the heavy lugs. Hopefully, its something that simple.

[typeSblood]

Tom,

I don't know the answer to your electrical problem, but I sure do enjoy your writing style.

Your inspiration from out of the past...

Andre Ampere

[Pat Dilling]

To repeat an oft used phrase on the forum: "It's a ground!"

Be sure that you have a ground strap from the motor to the frame/chassis. This sounds to me like the primary ground has been lost and electricity will seek the path of least resistance to find a ground. If that path is down a wire of insufficient gauge to handle the current it will melt the wire. I have had a couple experiences in my automotive life where this has happened. I would check the ground path before digging into the harness. Good luck and let us know what you find.

[brian6373]

I agree with Pat about grounds. I've added ground wires between the frame and engine and frame and body to make sure there are good grounds for all electricals. The most important is to make sure the batt. to engine has good electrical and mechanical connection. A test light works well for determining where power is, but if you don't have a volt/ohm meter to check resistance, it's hard to determine weather something is good or not. I would suggest H.F.'s cheapest meter. They will do what you need to do without investing a lot of money in an instrument that will be used infrequently. Good Luck, and let us know what you find.

[11SecAvanti]

Did the wire leaving the ammeter also melt? If so, the short or false grounding is coming further up the harness trail. If not then the short grounding is coming directly from the ammeter area. Check to make sure the feed through terminals on the ammeter itself are insulated from the casing metal. Also I have seen the headlight switching area short out to the casing frame. The terminals are tightly packed in that area.

[tluz]

Thanks, guys. Excellent suggestions as always. I got hung up cooking turkey soup today so had no chance to fry any more wires I will figure this out and let you know what I learn.

The one thing I did was to go to Walmart and buy a couple of fire extinguishers.

[tluz]

Thanks for this Jim. Not only do I appreciate the advice but also your support through this process. For what it's worth, your brake booster works perfectly!

[WCP]

Tom, you are not going to like what I have to say about your problem. Firstly, I suspect that you have a shorted diode or similar problem in that new alternator. Secondly, you have "bypassed" the regulator of the original circuit and therefore removed the circuit breaker that was meant to protect the wiring in the event of these types of malfunctions. You also mentioned that a 60 amp fuse has been added to the circuit. I surmise from that that the new alternator is also a 60 amp unit. Avantis don't need anything larger that a 40 amp unit and the wiring should be protected with nothing larger that a 16 gauge fusible link. A 60 amp fuse is way way too much.
Now for the bad news. If you have smoked a wire in a harness, then that whole section of the harness is suspect. To illustrate, some years ago I worked on a fairly valuable Avanti and one of the things I discovered was a wire that had been added outside of the harness that went from the coil to the ignition switch. It was apparent that the original wire had shorted probably by chafing on the bottom edge of the emission shielding. When I removed the harness and unwrapped that area passing thru the firewall, I discovered a melted solid mess of burnt wire and fused plastic jacketing. That car had presumably been driven many miles and changed ownership in that condition. It's a miracle that that car had not gone up in flames during its subsequent operation.
Don't look for shorts with a live battery.

[tluz]

Thanks, Bill. I gratefully accept all advice and am happy to have it, even if the news is not great.

Jim and I opened and inspected the harness today. Fortunately there is no more damage. I have removed and replaced the ammeter wire with new 14-gauge.

What we discovered is that the voltage regulator (bought new from SI) is cooked at the BAT terminal, where the hot wire from the alternator came in. We also learned that there is current running through the case when the case is grounded, probably as a result of the destruction of the insulation in the VR. The case itself is a mess, with the paint bubbled off and some warping of the metal.

Photos are attached.

There is no click at the solenoid with the ignition in the "on" position. Plenty of spark getting to the hot post in the solenoid and a spark at the negative post with the key turned on. Starter does not budge, however.

I have not yet tested Jim's theory of burned solenoid points other than to determine that big sparks occur when you touch the hot end.

Don't know if this changes anyone's views. Your thoughts on what the next test should be and how to proceed otherwise are welcome.

[StudeRich]

This may be a really dumb question, but is there a reason that the original Voltage Reg. was left in the circuit, when there is a Built-in one in the Alternator?