I have my wiring harness including charging system all attached to a remote insulated positive stud under my hood which is fed from the big hot lug on my mini starter which is fed by a 0g cable to the battery under my truck bed. The only things attached directly to the battery are grounds, the cable to the starter, and the constant power to my sniper EFI.

When I started and warmed up the truck this morning I thought I heard an extra whirring sound but I wasn’t sure- it’s a little loud with 3.5” exhaust. Everything seemed normal until I went to leave I noticed that my sniper dashboard was flashing yellow on battery voltage and it was down to 10v. Huh that’s wierd I thought- my autometer voltage gauge in the dash is reading 13.5 like my charging system is healthy and it sure cranked fast when I started it. Then the sniper battery volt gauge went down to 9.9, 9.8, 9.7, then smoke started pouring out from underneath with electrical fire smells!

I successfully shut off the motor with the key and unplugged the sniper main harness connector, negative battery cables, then positive cables, and the smoke from my starter tapered off. My engine bay is tight so I had the starter wrapped in a dei blanket held on with two neatly twisted shut loops of bailing wire. I think the fiberglass and foil blanket contained any fire if there was one. I suspected that I had wired the blanket on too tight or somehow crossed or shorted my 0g cable but at the time I just wanted to make it safe and get to work ten mins late and smelling like an electrical fire.

I just got home and started investigating, expecting to find my heavy cable all melted to hell. To my surprise it was the cable that’s part of the starter on the bottom that melted! If my trigger wire had shorted it would have stayed on and cranking despite removing the key and if the jackshaft had stayed popped out into the converter ring gear I expect I would have heard more mechanical racket?

What’s y’all’s guess on cause of death on this POS? Did I do something wrong that needs fixin on version II? I have another mini starter here so I guess I’ll just throw it in but wow this was a scary morning for a minute!

Open it up and take a look.
My guess is the motor itself because that wire is goes to the outer windings.
I just had one apart to replace the boot on the ring terminal and look over general condition.

Photos are in reverse order.
1st one is the motor.
2nd will be the solenoid removed
3rd will be the solenoid and cap.

I don't have my notes but expect both US ignition wrench sizes and metric sockets will be needed. maybe 11/32 1/4 11 or 13 mm?

Ring gear still looks good- barely got the purple paint scraped off the edges. I’m gonna fix it later this week but I got paranoid about my stall converter that only has two tanks of gas run thru it so far

I have a working used OEM one out of a dakota I’m gonna throw in. This one was a brand new DB Electrical SND0165 from amazon. I thought for $80 it would be decent. I’m guessing chinese though

That wire internal to the starter is only hot when the solenoid is engaged.

I suspect the issue was the solenoid and everything else was symptomatic.

I just wonder if the solenoid stuck then why didn’t the starter continue to crank when I turned off the ignition? Maybe the motor was already fried and making a dead short instead of cranking power? Then why don’t I see more ring gear damage?

Ugh I’m going to try and pull it for a better autopsy later today. I’m out to lunch after checking out the Philadelphia modifyers nistalgia drags at atco this morning. Gotta get her back running by tomorrow I have a tenative date with the chassis dyno around 7!

A starter motor that stays engaged with the ring gear will become a generator at a given RPM. This in turn fried the wire from the motor to the solenoid which likely led to a dead short and caused you voltage readings to drop

I suspect your solenoid stuck on, or the 12v signal from the ignition switch did not switch off thereby keeping the solenoid engaged. You got very lucky.
There would be no ring gear damage as the ring gear was driving the starter instead of the other way around.
And yes you probably correct that in the process the starter motor fried itself

BTW your starter cable lug needs to be properly crimped / soldered and should have shrink tube sealing the connection.

Thanks that would make sense. I was wondering how the motor being turned would play into the situation- it would make reverse polarity power right? Either that or a dead short or a combo must have been drawing down the battery voltage.

That cable is just a ground I don’t care what it touches. My hots are done up cuter with heavy duty shrink wrap

You need to treat your grounds with the same care as your hot cables. The supply and the return of an electrical circuit are equally important and by not sealing your connections you can allow corrosion to start and cause odd issues.

Hmm never thought of it that way. Ok y’all taught me something thanks.

Here’s the guts of the solenoid. The spring was still springy and the contacts don’t look mangled?

And my hots. I’ll shrinkwrap the ground ends too.

Do I need one of those sheetmetal starter shim things? I have gotten away with not ever using one so far but I also have a plain stud in the top mounting hole of the starter to the bell- the bottom edge of the casting lines up perfect from bell to starter...

My keyswitch gets fused power from the fusebox and a single run of wire straight through the firewall down to the trigger post on the starter for cranking. I am considering putting in a small red cranking voltage indicator light off the trigger wire for insurance. I have some holes open in the ‘54 dashboard from deleted pull knobs- choke, throttle, etc so it would fill one and look cool too. Then I would know if the trigger wire ever stayed energized.

I’m trying to avoid having this happen again soon. Right now my only suspect is that the imported probably chinese starter itself just freakishly died an early death. The one I installed today off the 89 dakota chassis donor vehicle and is also a mini style but about an inch longer than the dead one (which spun my 10.25:1 512 like a champ). Hopefully it’s the same one that MP sells for $150. It turned over the dak v6 nicely before I yanked it.

I'm thinking you are set (just a starter issue).

Thanks Robert

Holley wants the EFI constant power direct to the battery but I have a master disconnect on the negative cable from the battery (big nhra style switch but on neg not +) that I used while building and shaking down the truck before welding or letting it sit for a few days. Using it with the sniper constant ground still hooked to the battery side post led to wierd ground loop problems- the IAC was ticking like a clock and hunting around and the fuel pumps had a wierd low voltage ghost. I swapped all the chassis grounds to the same side of the switch and was using it only to lift the grounds on the fuel pumps in case of emergency (never needed it but the battery is somewhat tucked away and that makes me nervous).

Well this episode made me want to use it as a master disconnect again so now one side has my - battery cable and the other side of the disconnect switch has the fat grounds to the frame & block, the fuel pump grounds, and the EFI constant ground. Hopefully it won’t be too noisy.

I agree I was lucky but my system actually worked exactly as intended. The battery acted as a damper so the sniper only saw a slow voltage drop, and my secondary main cable (4g) from the fat starter lug (0g to batt + from there) has a 50 amp maxi fuse that blew when things got wierd. That’s why my autometer gauge read steady 13.5 while the battery was draining and the starter was waging war on itself. The front half of my harness was disconnected from the battery and perfectly happy to run off my ‘89 dakota alternator and brand new regulator.

It was a busy day- Atco in the AM then dinner guests, then the game of thrones finale, but I got the new starter in this afternoon and finished the wiring after the show. First I left the sniper harness disconnected and tried my key. All my lights and gauges are working and the starter hits and turns over the motor nicely. It disengages quickly with the cranking pressure off the key left in the run position. I crossed my fingers and plugged in the sniper main harness. No wierd noises with the master disconnect off so I turned it on and still good. I turned the key to run and the sniper dash came to life and I heard the fuel pumps come on then off like normal, the injectors priming, and the IAC valve parking. So hopefully that’s all good too. I didn’t want to wake up the neighbors so I’ll test it out for real tomorrow.

Thanks for all the helpful responses fellas!

Radar

You may need a relay in the circuit depending on how much current the starter solenoid draws and what your ignition switch contacts are rated for. This may or may not be the root cause of the problem.

Also as previously mentioned you cable crimps look a bit suspicious. They appear to have been just flattened rather that crimped with a proper tool and / or soldered.

Yup that long 4g negative cable was kind of an add on after everything was done. The heavy copper lug was indeed just smashed flat in a vice instead of crimped in my press and soldered and shrinkwrapped like my positive connections. I was under the impression that a good crimp that wouldn’t let go and didn’t break any strands was the gold standard in aerospace? Maybe I heard wrong?

The whole truck I tried to only make a few connections and splices which were neatly soldered and heat shrinkwrapped. Every other connection is either weatherpack connectors (insulated dry crimp terminals) or ring terminals (dry crimp and sometimes shrinkwrap). There are no extra connections in runs of wire, barrel crimp connectors, twist & tape, any of that nonsense. All my ring terminals and the few spade connectors here & there (msd coil, hhr fan) are well protected with dielectric grease.

I never tried that hard to keep ground connections as tidy as hots- I always figured that if they touch somewhere other than the bolt or lug who cares it’s not gonna spark or cause problems. The thing that convinced me to change my ways and start shrink wrapping grounds was the idea that I don’t want my crimp with bare wire showing to turn green and powdery and lose efficiency. The grease will eventually go away and the green will set in so doing a better job there makes sense.

I had a feeling my my keyswitch could possibly be the problem too. I didn’t put a relay but I did divorce it from the keyswitch. Now I have a 30 amp momentary switch for cranking, fed by a fuse in the run bus.

marine heat shrink with the sealing glue inside, is what i am using these days. that stuff is great in my opinion.