My engine wiring harness burned up a couple wires yesterday!

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timk225 said:
The tan alternator power wire goes through the large plastic plug on the firewall, next to where the steering column goes through. There are no other wires on the ammeter. Just the tan going in and a red wire of similar size coming out to the starter relay.
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Factory heavy duty should be a rubber grommet, and the hole should be in one of the locations the factory dimpled for that purpose.

Unfortunately not many examples of heavy duty alternator wiring have been shared or spotted. I think the link above is the only '73 on FABO with this ptional wiring photographed.

If your car had this option, but without rear defrost grid, then perhaps the power is getting to the main splice through the standard alternator output wire.
 
I got some more information on the alternator today. I dropped the starter and alternator off to be cleaned / regreased / rebuilt / repaired, and the old guy who ran the place gave me some details. He claimed the alternator was a later "thin stator" unit from the late 70s or early 80s, likely installed in a K car. The dedicated ground stud was needed because those cars used rubber alternator mounts. Thinking back, I remember those, and yes it is likely true. He said it might be good for up to 70 amps, that needs to be tested.
 
Sounds like a guy who knows his business. If he has an earlier one that draws less field current, I think the voltage regulator arnd wires will have an easier time doing their job and survive longer.
 
I've been working on the wiring. I got the new wiring harness in the mail, and took it to the car to check the lengths. I had to extend 7 wires, for the temp sensor, oil pressure sensor, electric choke, coil, and distributor. I quickly found crimp connectors to be useless, even when crushed hard with vise-grips, the wires pulled right out. So I trimmed the ends of the wires back a half inch and meshed them together, and used a few strands from each wire to wrap around, then soldered them all (60/40 lead & tin solder) and put heat shrink tubing over them.

Today, I went to the car after work and started carefully pulling the old wiring harness out. And in doing that, I found 2 more areas where the wire was burned through the insulation and tape wrap! One was right over the rear edge of the valve cover, I guess it shorted out on that, and then one more spot above the brake booster. Here's a photo of the brake booster one.

I wasn't planning to make a 4th Duster repair video, but I've been videotaping parts of the project so far and taking photos. We'll see how it turns out.

Since I'm already getting the alternator rebuilt, which was going to happen, electrical problems or not, and I got a couple new ballast resistors, and a new voltage regulator, I might as well go ahead and change the coil too. It is tan and looks a little shorter than a stock black Mopar unit.

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Visegrips! Well now you know. At least you checked first to see if they were holding.
What you did should hold. There are issues with soldered joints, but also some advantages. Make sure they are supported and aren't getting strained or vibrated.

Splicing with open barrel can be done with or without soldering. Open barrel terminals are nice because most have a crimp that holds the insulation and provides better support.

Inline wiring splice clips........from the Dodge RAM service manual

!!HUH!! Old man learned something. Was into the Dodge ram service manual and saw a little drawing about inline splice "clips" A simple little "U" shaped clip that you wrap around the "running" wire along with the "to be added" tap wire, and crimp. Solder........Makes a...
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There are other methods that work. Here's one

Clever splice

Saw this a few months ago, just saw it again. Clever splice, looks very strong. WNEC™ - Waterproof Solder Wire Connectors
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If you want OEM type terminations, the original terminals are almost all "open barrel" terminals. Sometimes available in parts stores, often easier to order them. Same with the open barrel crimpers.

Sources for Chrysler type wire terminals

Found some on-line retailers for the 'mopar' style terminals. A couple places call them Packard 58. Need to confirm what covers. Only thing I don't like is one place claim the one covers 3 wire sizes; and the other place skips 16 AWG, and the third only carries one size? Eastern Beaver Open...
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You

A bit of Wiring 101

It seems like the official FABO winter project for 2021 is rewiring your car. A lot of folks have been asking wiring questions over the past couple weeks so I thought I'd try a bit of a how-to. I'm rewiring my 64 Dart wagon after it decided to melt most of the underhood wires into a big mess...
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www.mymopar.com for scanned service manuals, parts books, and Master Tech conference.
Master Technician Service Conference - Chrysler's Training for Mechanics The on-line Imperial Club has a better index of the Tech Conference.

The 1970 Hamtramck Registry Library Page (1970 - 1974) Has Service Bulletins (updates to the parts and service books) and Sales Information (such as options for buyers)

For closed barrel terminals and wire Ancor marine wire products are pretty good. They are carried by chain stores such as West Marine. Some West stores also have reels of marine wire in a wide range of sizes and insulation colors. The wire on reels is sold by the foot. The majority of stores have a more limited selection. They probably also have heat shrink tubing - I always buy from McMaster-carr so haven't paid attention. Mcmaster has oil resistant shrink tubing as well as colors and flexible shrink tubing. Which is best to use depends on the location.

A place to mail order wire in smaller quatities is Wirebarn
 
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timk225 said:
I have a post in the Racing forum, wherein I took my 1973 Duster /6 out for a speed run and made it all the way to 87 mph, followed by the ammeter going to full discharge, a big backfire or loud POP, followed by a brief pause on the side of the road.

This morning the car would not start up. It cranked fine and had gas, but no spark. I researched testing coils and distributor pickups today at work, put the time to good use.

So this evening I started getting into the engine wiring and found what caused the problem. An alternator field wire had finally had enough of its 52 year old insulation, and shorted out a wire along the valve cover hard enough to make about a foot of insulation disappear. I unwrapped the wiring enough to get that wire all pulled out of there, from the alternator to about the #5 spark plug.

As for the distributor pickup, when I test its resistance at the plug, I'm getting 400 ohms, which is in the good range. But then I go to the ECU plug and test it there, I'm getting 8 ohms. So something is still shorted out in there somewhere.

I can bypass the factory wiring and run wires directly from the distributor plug to the ECU plug and see if it runs. I did the same thing back in '10 on my '89 Dodge Turbo Spirit 2.5 when one of the 4 injectors decided to start firing when it shouldn't, causing fuel to drip out the tailpipe and contaminate my new engine oil with gas. I eventually traced it to the #3 injector and used a junkyard injector wiring plug to bypass the factory wiring and run a new wire the the computer plug for that cylinder. It ran fine like that for the remaining 3 years I had that car.

As for my Duster, the most amazing thing to me was that after the wire shorted out, once the engine sat for a couple minutes, I started it and drove it 20 miles, including a stop and restart along the way with not a single problem, then this morning it wouldn't start.
Click to expand...

I've heard of this before.....your going to need a V8
 
I think I understand now, you had to extend wires on a V8 harness to fit your slant 6?
 
str12-340 said:
I think I understand now, you had to extend wires on a V8 harness to fit your slant 6?
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Yes.

I got the old harness out yesterday and got the new one mostly all in place. Just have to install the new coil, and pick up the starter and alternator and get them back in, then I can start it up and see how it goes. It sure was nice working with new wire that can flex and move and isn't all hard and stiff and greasy. All my extensions were long enough. The temp sensor got a 15 inch piece of wire spliced in, and to my surprise, that was just long enough. It has some slack in the wire, so nothing is pulled tight, but I thought it'd be longer.

I'm also going to put in a new wire to activate the A/C clutch. For some reason, the factory wire was partly replaced, but the original piece that is there goes forward past the fuel vapor canister, through the hole in the radiator support towards the front marker light, then the first wire ends and a second wire connects to it, then it comes back through the radiator support and on to the A/C clutch.

And I'll leave it unplugged for now, as the old A/C system is low on refrigerant and there's no point charging it up or converting it to R-134 until I replace the heater core and maybe the A/C evaporator. Don't want the A/C clutch accidentally getting turned on and running with an unknown amount of refrigerant / oil in the system. It is all OLD.
 
Don't know if it's been mentioned but I think the first thing I do would be to take that voltage regular off, clean the surface that it's mounted to. Looks like its covered in turds.

Also there's quite a bit of splice'ins going on
 
I didn't want to do any splicing, but M&H doesn't make a Slant 6 version of the wiring harness. All the extensions are in the plugged in part of the harness, from the rear of the /6 valve cover on. So making a special version shouldn't be a problem, except for sales and profits.

I wasn't sure if the old voltage regulator got damaged or not, so it is being replaced. The ballast and coil are also being changed. The old ballast tested ok, about 1.8 and 5.8 ohms, so it will be a spare. And I'm not putting the new voltage regulator on those standoffs that the previous electrical genius had engineered, it is already bolted to the firewall next to the brake booster, where it should be, with clean connections for grounding. I may run another wire from its metal case to ground, just for extra grounding.

I just talked to the guy rebuilding the starter and alternator, and got some interesting news. According to him, the fan came loose from the rotor in the alternator and grounded itself out. Seems like a good way to burn up some wires. And it happened just as I was doing a SPEED RUN, so that alternator was likely at the highest rpms it has seen in a long time. He said the fan is spot welded to the rotor, he replaced the whole fan / rotor assembly with another used one he had.

So that one field wire got a whole lot of power shoved down it the hard way! Maybe it wouldn't be a bad idea to add a few in line fuses.
 
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Here are a couple photos of the old alternator rotor. The initial point of failure. The rebuilder guy said my starter was a 1976 model and the alternator was either a 76 or 78, the date in the circular year casting mark was hard to read. Anyway, here is how the fan came loose from the rotor and contacted the insulated field wire tabs, thereby making them non insulated. The fan doesn't wiggle around all over the place, it just spins about a half inch in either direction instead of being welded in one spot. The rebuilder said he has seen few failures like this over the years.

I got the rebuilt starter and alternator put back into the car today, along with a new coil. And I used the original capacitor to the coil + bolt. My multimeter showed it testing at 0.8 uF. How much capacitance is it supposed to have? The Slant 6 started right up and idled nicely, the ammeter was charging at nearly 40 amps for a good 20 minutes, then it settled down to about 25 amps by the time I got done doing some other things on the car. The battery needed power put back into it. While charging at 40 amps I was at 13.7 volts across the battery terminals.

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You'll be lucky if some of the connectors don't look like this now
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and this
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Also the battery got cooked. About 10-15 amps is typically max charging rate.

Charging Battery with Alternator - Warning

We've discussed this here more than a few times. Usually about how easy it can be to cook the battery or overloading the charge wiring. Here's another reason. "Any attempt to charge a low battery by the alternator will result in stator windings burning out" ebay item # 222689173585 This is...
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Nah, it's fine. I think. It better be. The repair shop said it was a 70 amp alternator. Also, my alternator + charge wire doesn't run through the firewall connector. It is a separate heavier wire that runs directly to the ammeter then to the starter relay, and it has a thin purple fusible link at the relay end. Nothing blew. I have the alternator charge wire from the new wiring harness taped over and out of the way at both ends.

If anything it was a good load test of the system. The battery is new, or at least it was new last August.
 
The battery is getting a normal charge now. I borrowed a battery charger and it began charging at 8 amps a couple hours ago. It is on 1.5 amps now.
 
Everything seems to be ok. I let it charge for a few hours last night, then it got done, so I switched it to some sort of reconditioning option it had (Black and Decker charger) and let that run all night.

Today I put a total of 57 miles on the car, went and filled it up with 90 octane ethanol free gas at a Sheetz station in the area, then took it out on the highway for a longer ride home. I got to my one good area for speed runs, pulled over and waited for the cars to clear out to give me an empty piece of highway, then ran it up to speed. I made it to 102 mph. The Slant 6 was running around 3600 rpm and I had the throttle mostly open, but any more would have it pinging. Once I got home I pulled a couple degrees of timing out so now it is around 3 degrees initial timing. It probably needed to be done anyhow, as I was having trouble getting it to hot idle under 1000 rpms. But once I pulled the timing back a little it was able to do it more easily. The throttle blade on the 1920 Holley is fully closed and it runs on the idle circuit, as it should.

I recorded enough video of the repair process, so I can make a part 4 Duster video sometime soon.
 
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