Wiring caught on fire when driving

[a_nelson]

Hi - I've been utilizing this forum for several years now and have always found valuable information, so thanks for that, but I've never posted before. I have a 1949 8N that gets limited use, mostly for assisting with work around my property, pulling trailers, mowing tall grass with the brush hog, etc.

Today I was cutting down some tall grass. Over the past 10 days I've used the tractor about 4 times, for an hour or so each time. It has been running fine. Today was no exception, until about 45 minutes into a mowing session the tractor abruptly turned off and smoke started pouring out from under the hood. I hopped down to see at least one wire glowing red, and several of the wires in the harness smoking. I assume they were glowing red too and burning off the fabric shroud they have around them.

Any ideas what may have caused this? Is this as simple as replacing the wiring, or are there other potential issues? I posted a short video on youtube, here's the link.

https://youtube.com/shorts/D6RVCe14KK4?feature=share



This post was edited by a_nelson on 10/18/2023 at 06:19 pm.

 

[used red MN]

Wiring improperly tied down or in a improper loom
wore through its insulation and shorted out. Is it a 6
volt system with a generator or is it converted to a 12
volt? Has an alternator been installed?

 

[a_nelson]

(quoted from post at 02:12:32 10/19/23) Wiring improperly tied down or in a improper loom
wore through its insulation and shorted out. Is it a 6
volt system with a generator or is it converted to a 12
volt? Has an alternator been installed?

It's a 6V system, so it has a generator, not an alternator, at least that's my understanding. I replaced the wiring harness about 4 years ago, and tied it down to all the same points as the original wiring.

If I'm going to take the time to rewire it again, does anyone recommend converting to 12V?

 

[JMOR]

(quoted from post at 06:24:06 10/19/23)

(quoted from post at 02:12:32 10/19/23) Wiring improperly tied down or in a improper loom
wore through its insulation and shorted out. Is it a 6
volt system with a generator or is it converted to a 12
volt? Has an alternator been installed?

It's a 6V system, so it has a generator, not an alternator, at least that's my understanding. I replaced the wiring harness about 4 years ago, and tied it down to all the same points as the original wiring.

If I'm going to take the time to rewire it again, does anyone recommend converting to 12V?

have both and I go by, "If it aint broke , don't fix it!" If 6 is working good for you, leave it working good, but if not or when you need to replace generator/regulator, then it is, in my opinion, time to go 12v alternator.....probably cheaper and better reliability.

 

[Mad Farmer]

(quoted from post at 03:24:06 10/19/23)

(quoted from post at 02:12:32 10/19/23) Wiring improperly tied down or in a improper loom
wore through its insulation and shorted out. Is it a 6
volt system with a generator or is it converted to a 12
volt? Has an alternator been installed?

It's a 6V system, so it has a generator, not an alternator, at least that's my understanding. I replaced the wiring harness about 4 years ago, and tied it down to all the same points as the original wiring.

If I'm going to take the time to rewire it again, does anyone recommend converting to 12V?

Looks like charge wire from generator shorted out? Single wire 3-brush genny?

When I redid my 9N I mounted the cutout on the genny so I can jumper it when they go bad, I have a short jumper tied to the wire so I can hook that up quick when/if cutout goes bad.

The charge wire to Bat I replaced I got from an electrical supply store. Real heavy insulation and I think it was 8ga? I routed it through the conduit the plug wires use. That was 30 years ago.....

 

[Jim in LA]

I kept our 49 8N 6 volt after rebuilding the engine. Its a 3 wire generator and works fine. If the
genny is messed up but can be repaired by starter/alternator/generator repair shop, then I would
not upgrade to 12 volts. I did have to upgrade on My 51 and it was expensive and a lot of
aggravation. I also burned one wiring harness due to mistake on my part. There are wiring
diagrams on this site. Search the 8n forum for wiring harness.

 

[Jim L WA]

That's a bummer. Another thing to check is the terminal block got shorted to the dash. Let us know what you found.

 

[a_nelson]

(quoted from post at 13:22:07 10/19/23)
That's a bummer. Another thing to check is the terminal block got shorted to the dash. Let us know what you found.

Thanks everyone, I am going to replace all the wiring and see what happens. I need my neighbor to tow me off the hill behind my house first though!

I should also mention that a couple minutes after I shot that video, it starting cranking the starter on its own. The ignition was off. I ended up just pulling the battery to get it to stop. Could the starter solenoid be shot, or was this just because that yellow wire burned up and now there is a short?

 

[JMOR]

(quoted from post at 11:25:34 10/19/23)

(quoted from post at 03:24:06 10/19/23)

(quoted from post at 02:12:32 10/19/23) Wiring improperly tied down or in a improper loom
wore through its insulation and shorted out. Is it a 6
volt system with a generator or is it converted to a 12
volt? Has an alternator been installed?

It's a 6V system, so it has a generator, not an alternator, at least that's my understanding. I replaced the wiring harness about 4 years ago, and tied it down to all the same points as the original wiring.

If I'm going to take the time to rewire it again, does anyone recommend converting to 12V?

Looks like charge wire from generator shorted out? Single wire 3-brush genny?

When I redid my 9N I mounted the cutout on the genny so I can jumper it when they go bad, I have a short jumper tied to the wire so I can hook that up quick when/if cutout goes bad.

The charge wire to Bat I replaced I got from an electrical supply store. Real heavy insulation and I think it was 8ga? I routed it through the conduit the plug wires use. That was 30 years ago.....

ell for the 11 1/2 amp generator,that 8GA wire ought to do it, fusing current 473amps!

 

[Hobo,NC]

Its a wonder this does not happen more if it did the use of a fusible link would have saved the day.

fusible link

 

[Eman85]

How can you watch and video while your tractor is burning?, not my first impulse.

 

[a_nelson]

(quoted from post at 11:50:19 10/20/23) How can you watch and video while your tractor is burning?, not my first impulse.

Great question, but I was in the middle of a field with no fire extinguisher, so there wasn't much I could do. It didn't seem like something that was going to burn the entire tractor, so I got a video. Then I ran down to my house to get some tools to unhook the battery. By the time I got back to the tractor the smoldering wires were out. I guess I wasn't that concerned while it was happening. Maybe I should have been.

 

[used red MN]

How can you watch and video while your tractor is
burning?, not my first impulse.

That was also one of the first thoughts I had. This guy
does not have a pliers or something else to get the
battery cable unhooked??!! I would recommend at
least keeping some kind of tools with you or in a tool
box on the tractor for these types of emergencies. If
that short would have comprised a fuel line and caught
the tractor on fire it would have been a much bigger
issue for you.

 

[a_nelson]

Yep, indeed I messed up and it could have been way worse. I had to remove the toolbox at some point and never got it back in there. Normally I have a set of tools in the box ready to go.

thanks to everyone who helped me diagnose what may have caused the problem. I ordered new wiring and will install soon.

 

[Eman85]

(quoted from post at 10:02:05 10/20/23)

(quoted from post at 11:50:19 10/20/23) How can you watch and video while your tractor is burning?, not my first impulse.

Great question, but I was in the middle of a field with no fire extinguisher, so there wasn't much I could do. It didn't seem like something that was going to burn the entire tractor, so I got a video. Then I ran down to my house to get some tools to unhook the battery. By the time I got back to the tractor the smoldering wires were out. I guess I wasn't that concerned while it was happening. Maybe I should have been.

Not picking on you, it's just something I see a lot of both on the net and on TV. People will make videos on their phones as their first reaction to a situation instead of taking action. I don't carry my phone especially on the tractor so I guess that's why I don't understand it.

 

[Caryc]

Below are two things that would have been very advantageous for you to have had on your tractor. I would still install both.

A fire extinguisher
A battery disconnect