Hot Rods Where there's smoke...

After I got the trans tunnel more or less finished, I got in and was going to start the roadster. I turned the key, and nothing. Turned it off, back to "Start", and white smoke BILLOWED from under the dash and the firewall.
I ran to the back of the car and unhooked the battery, then ***essed the damage. The + feed from the starter to a junction block to the ignition and alternator was HOT, and black plastic insulation bubbling through the linen wrap.
What the???
I pulled the gauge pod, no connections or wires bare touching the dash or anything that I could see, so I got my multi-meter out and began testing continuity. Then I touched the ignition feed to the coil, and then to ground, and got a tone.
That's not right, so I tested the "Ignition" post on the switch, in the "ON" position, and ground. Tone. Switch off, no tone. Same at the coil.
So, what I think is the issue is the (new) ignition switch is faulty, and grounds internally when in the "ON" position. I'll get a new one tomorrow, and evaluate the wire from the starter post to the ignition switch. It's OK, I think, but it looks bad, so I'll probably have to get a length of new wire from Rhode Island Wire to replace that little section, about 10 feet long. I'm glad, and pretty lucky, that I was able to intervene before the entire harness melted, or caught fire and burned the car to the ground.

 

I thought you were going to say it was your pertronix
...that wasn't nice...
Fast reflexes and good save

 

Crazy how fast it can happen, I still haven't ordered a new harness to replace my melted one for my 41 yet

 

Lucas wiring?

 

LOL, that's COLD, man!

 

yep, wiring may work for a long time. but, hiding may be corrosion, brittle strands, weak grounds, etc. might consider putting a kill switch under car for easier access during emergency

 

here, in California, already have too much smoke from fires

 

Uh, it's all brand, spanking new stuff.

 

I'm just thinking that when something like that happens I usually end up going back to see if anything happened while I was doing the last thing I did that may have caused an issue.

 

I sometimes cheat traditional, and put a fusible link in the main power feed wire from the battery connection at the starter (or starter relay, or at the battery, depending where it is on the car). I don't know if it would help, because I've never blown one out....but still....

Glad it didn't do much damage! scary stuff.

 

I see some wires very close to the CAD built trans tunnel,,,,,hope that wasn’t an issue ?

Tommy

 

Funny story involving Lucas wiring. Back in 1980-81, I was stationed in England and driving my (ot) '67 Mini Cooper. I noticed smoke coming from my wiring and hit the brakes to stop. No brakes, what, the brakes are hydraulic, not electric, what's going on? Anyway, I get stopped and find the problem. The connection on the electric fuel pump on rear sub frame had been rubbing on the brake line. Just as it rubbed thru, the wire shorted and fluid came out at the same time...wire smoking and no brakes. What a coincidence.

 

- next time spend more time letting those know exactly what you are working on when you ask for help -sounds like installer error - hot/power wire connection wrong

 

They were, in that photo. I broke that neutral safety switch trying to bend the prongs a bit to get the wires away from that edge. Turns out they're brittle and do not bend. I had them disconnected from the switch and wired with a jumper to try to start the thing. New switch for the shifter on the way, and I 'll get a new ignition switch.

 

Never in this thread did I ask for "help". Next time you offer "advice" consider whether it's been asked for. I'm relating what happened. The switch is most definitely shorted internally. With the battery disconnected it goes to ground in the "On" position. That's not "installer error", that's a faulty switch.

 

Was the faulty switch something that we should watch out for ? Or do you feel this was a single occurrence ? Name brand , off brand , generic ??

 

Brand new stuff isn't always good stuff ................

 

Obsessing about the near immolation of the roadster yesterday, I got up at 0630 and went out to the shop to look at things when I wasn't all jacked up. Here are some photos of the offending (offended?) 12V lead from the battery lug, to the (now used only as a junction block) voltage regulator, to the ammeter. It's the ONLY wire that got hot. The lead from the regulator to the alternator, not damaged. The lead(s) from the ammeter to the switch don't have insulation boiled from the jackets, but the switch itself was HOT to touch several minutes after this all happened and took it out of the gauge pod.

As was suggested I'm going to put a 50A fuse in the 12V wire from battery lug on the starter to the junction block and thence to the ammeter. That should prevent the harness from going up in smoke, ala Sir Lucas, Prince of Darkness. I thought perhaps the "hot" post on the ammeter could have contacted the back of the dash, or perhaps the bracing for it or even the bourdon tube for the temp gauge, but no, everything clears with plenty of room, as it did when the dash was in a '52 DeSoto.

I'm also getting a new switch, and enough wire to replace that lead that's damaged (ordering from Rhode Island Wire monday), although I'm going to byp*** it for now with some new 10 gauge, and just abandon that wire until I get the new piece.

I know ammeters aren't used in new cars today for this reason, but that doesn't seem to be the root of the problem, as I (nervously) hooked up the battery, and turned on the key, and with no smoke anywhere, fired it up like nothing ever happened. I DID find the "Ignition" post on the switch wasn't tight, (I could swivel the connector), and the post on the ammeter wasn't fully tight either. Either one of those things could have lead to resistance, and thus heat in that wire, but I'm still laying blame on the parts store tractor ignition switch being intermittently shorted. It did go to ground last night when I tested it while it was still hot from the near blaze.

 

Absolutely true. I was just pointing out that old, corroded wires and connectors weren't the problem. My finding that two of my connections weren't tight may well have been the problem, and I'm going to fix all that too. Along with that parts store tractor ignition switch...

 

It's a generic, tractor switch from NAPA. No "Accessory" position, just "Off", "Run", "Start". And, "Smoke"...

 

Brian while you are fixing things up why not add a kill switch? You are right this could have been so much worse. I have one near my battery in the trunk and when the car sits for semi long periods of time with a tender on it I hit the kill switch just because...

 

Bought one just this morning with all the other stuff, including a 150A breaker. I think I'm going to byp*** the ammeter as well, the alternator has an idiot light lead that I didn't use (but is tucked up behind the gauge panel), so I can just eliminate that potential problem source as long as I'm re-doing things.

 

That's crazy f'd up...glad you acted quickly and are safe with somewhat minimal damage to the goods...walk arounds and just grabbing connectors and giving a little wee twist isn't a bad idea especially after a good drive every once and awhile...that said if a component fails that's hard to check...

 

Please consider a short in the ammeter. This picture shows dis-colorization (and an overheated wire) on only one terminal of the ammeter. The other terminal and the wires show no sign of heating. I would suspect that the wire to the ignition switch would show sighs of heating.

Good luck, Russ

 

In my Buick I replaced the Ammeter with a voltage gauge. Just took an aftermarket gauge apart and used the guts behind the stock dash gl***. Now 12 volts is straight up and to the right of center is more. If the needle goes left of center I know it is discharging.

 

+1 on the shorted ammeter; my first thought when I saw that picture. Just for the record, resistance at a bad connection will cause heat at that point but not in the wire that feeds it, which will actually be carrying less current than it would if everything were tight.

 

Your short is at one end or the other of the wire that got so hot. I'm guessing the ammeter has a problem. If the wires to the ignition switch didn't fry, it isn't the switch.

Your continuity check from the coil to ground includes too many circuits to be a real valid test. The power lead at the coil is connected to the ignition switch which in turn is connected to most of the circuits in the vehicle. You were really checking a whole lot of circuits at the same time.

 

Glad things didn't go 5 alarm, I so enjoy all your builds and posts.
Just would like to add a thought, is it possible that a bad ignition coil or something else on that circuit is faulty? If the ignition switch was overloaded it may have shorted it out..
You know, trying to figure out if it was the chicken or the egg.

 

He said the nut on the ammeter was not tight, that would explain why that side got hot. Also, we don't know the size of the melted wire, vs the size of the wire on the "cold" side of the ammeter. The smaller wire will get hot, the larger one won't, when two wires of different sizes are in series, and subject to a lot of current.

Still would be a good idea to closely examine the ammeter, as insulation might have been damaged by the heat.