57 Battery Gauge Fire (almost)

[Ashley S.]

I just experienced a potentially major problem, but fortunately it didn't do any damage. The black wire going to my battery gauge under the dash caught on fire. My cousin and I were able to put it out fairly quickly. I think all I have is some smoke and soot to clean up.

My question is why did this happen. I'm sure I did something wrong but I want to understand what I did.

Here are the facts.
1) Per a couple of the posts I found on here, I reversed the leads going to this gauge since I was reading backwards before. This is opposite from the AIM.

2) We were trying to get the motor started. We had run the starter quite a bit and were changing the timing to try to get it to start.

3) We were using a battery charger on the "start" setting along with the battery.

Are any of the above items part of the problem. I can't say for sure that a wire wasn't pinched or something, but it is hard to tell at this point.

Any thoughts or questions would be appreciated. I need to be comfortable that I won't do this again.

Thanks,

Ashley

[Richard M.]

Re: 57 Battery Gauge Fire (almost)

Ashley, sorry to hear of your trouble....these things can make you loose sleep.....

The 14 gauge black wire is from the solenoid battery feed post. What happened is obviously an indication of excessive current flow through it.

It could be caused by a low grade short, or simply a "bad connection" either at the solenoid post or at the ammeter, or further along the path to the ignition switch and solenoid energizing circuit. This includes the red wire to the ignition switch, and the purple wire from the switch to the "S" post on the starter solenoid. It's possible the ignition switch or the starter solenoid is a problem. I would check all connections first, and would make sure all terminals and posts are freshly filed & cleaned.

If you were cranking for a long time, this will certainly warm things up. If there are any poor connections, it adds extra resistance(current) to the paths and possibly could cause what you saw.

The starting circuit draws much current and I could never understand why GM didn't use a relay in this path to minimize the current flow through the ignition switch.

Did the engine ever start?....you didn't say. Did you polarize the generator?

Rich

[Gary C.]

Re: 57 Battery Gauge Fire (almost)

Ashley, when I start a motor for the first time I set up temporary wiring between the key components required to to just start the engine. Similar to what would be used on a test stand. And use a Snap On hand held button remote starter. Fan belt is on to move the water pump, but nothing connected to generator. No wires connected to the starter or ignition resistor other than what's required temporarily. This way you can't melt any of the wiring harness. Especially when using a battery charger for a start boost. JMTCW, Gary....

[Joe R.]

Re: 57 Battery Gauge Fire (almost)

Gentlemen,

I don't know about your battery charger but my charger has a start cranking assist of 200 Amps. You should NEVER use the cranking assist on a car with 40+ years of electrical technology. Even with NEW wiring it is NOT engineered for such a boost, for long periods of time. Like cranking for prolonged periods.

Be patient and CHARGE your battery with a 10amp charger for 12 hours and then try to start your Corvette. If it doesn't start in say 5 seconds, find out what's wrong and try again.

JR

[Pierre J.]

Re: 57 Battery Gauge Fire (almost)

Be patient and CHARGE your battery with a 10amp charger for 12 hours and then try to start your Corvette. If it doesn't start in say 5 seconds, find out what's wrong and try again.

JR[/quote]


I agree.
Pierre

[Ashley S.]

Re: 57 Battery Gauge Fire (almost)

Richard,
Thanks for your advice. I was not able to get it started. When the incident happened, we called it a night. I was tired a frustrated at that point so we stopped for the night.
I had trouble keeping my timing set right. My distributor cap and rotor don't seem exactly right. I've seen on several occasions that the rotor tip is moved (presumably from hitting the rotor cap). It is very tough to keep this from happening. Do you know if it should be this easy for them to touch? I try to get the cap on EXACTLY right, but sometimes that doesn't always seem to be enough. It was for this reason that we were having trouble starting last night again.
The other thing I'm going to need to do is to verify the integrity of my harness now that I know I've overheated part of it. Any thoughts on this?

Ashley

Ashley, sorry to hear of your trouble....these things can make you loose sleep.....

The 14 gauge black wire is from the solenoid battery feed post. What happened is obviously an indication of excessive current flow through it.

It could be caused by a low grade short, or simply a "bad connection" either at the solenoid post or at the ammeter, or further along the path to the ignition switch and solenoid energizing circuit. This includes the red wire to the ignition switch, and the purple wire from the switch to the "S" post on the starter solenoid. It's possible the ignition switch or the starter solenoid is a problem. I would check all connections first, and would make sure all terminals and posts are freshly filed & cleaned.

If you were cranking for a long time, this will certainly warm things up. If there are any poor connections, it adds extra resistance(current) to the paths and possibly could cause what you saw.

The starting circuit draws much current and I could never understand why GM didn't use a relay in this path to minimize the current flow through the ignition switch.

Did the engine ever start?....you didn't say. Did you polarize the generator?

Rich

[Chuck G.]

Re: 57 Battery Gauge Fire (almost)

A tremendous amount of "juice" goes through that ammeter.

When I had my 54, I had a similar thing happen. Was cranking and cranking.

The ammeter got so hot it melted the plastic lens.

The gauge looked like a Salvadore Dali painting....

I had no fire, but LOTS of heat.

Chuck

[Richard M.]

Re: 57 Battery Gauge Fire (almost)

The other thing I'm going to need to do is to verify the integrity of my harness now that I know I've overheated part of it. Any thoughts on this?

Ashley

...yes, you'll want to check your harness carefully. You may have to get in there and replace something. If it was just a bad connection somewhere maybe you're ok. It's hard to tell where it may be damaged......if it is.

You may want to consider a fusible link at the black wire at the solenoid, or one of these... http://www.sportsmansguide.com/net/cb/cb.aspx?a=262984

Rich

[Mike B.]

Re: 57 Battery Gauge Fire (almost)

Ashley,

In answer to your question about the distributor cap, the rotor should NEVER hit the cap, knocking it out of adjustment or otherwise. You either have the wrong cap and/or rotor, or simply have the cap in the wrong clock position to sit squarely on the distributor. There is a molded tang that protrudes from the bottom of the cap which should mesh with a like notch in the top rim of the distributor. Be sure that those are lined up before securing the cap. If the cap was in the wrong position, you will have to move the plug wires to the correct tower positions. The #1 plug tower faces approximately towards the front driver side headlight. If at any time during the starting attempts you get horrendous belching and fire breathing out of the carburetor, STOP! That is a sure sign that the timing is still wrong (but not the only thing that could be wrong such as intake rocker arms that are too tight). Double check the firing order and position of the plug wires using a proper diagram available in virtually all Chevy repair and tune up manuals.

Regarding the fusible link - that is a good idea. Fires like you describe have consumed many Corvettes over the years. I've attached a thumbnail photo of one that I wired in a few years ago. I mounted so that I did not have to cut the eye off of the original wiring harness (black wire) and used a fabricated jumper lead (red wire) to complete the circuit. Note that the photo was taken during mock up - the thick, red battery cable is not yet attached to the common post.

Post again if you need any more help or ideas.

Mike

[Ashley S.]

Re: 57 Battery Gauge Fire (almost)

Thanks Mike. I will definitely be adding some type if circuit protection as you described. The more I've looked at it, the more vunerable I see that it is. Thanks for the pics and advice.

Ashley,

In answer to your question about the distributor cap, the rotor should NEVER hit the cap, knocking it out of adjustment or otherwise. You either have the wrong cap and/or rotor, or simply have the cap in the wrong clock position to sit squarely on the distributor. There is a molded tang that protrudes from the bottom of the cap which should mesh with a like notch in the top rim of the distributor. Be sure that those are lined up before securing the cap. If the cap was in the wrong position, you will have to move the plug wires to the correct tower positions. The #1 plug tower faces approximately towards the front driver side headlight. If at any time during the starting attempts you get horrendous belching and fire breathing out of the carburetor, STOP! That is a sure sign that the timing is still wrong (but not the only thing that could be wrong such as intake rocker arms that are too tight). Double check the firing order and position of the plug wires using a proper diagram available in virtually all Chevy repair and tune up manuals.

Regarding the fusible link - that is a good idea. Fires like you describe have consumed many Corvettes over the years. I've attached a thumbnail photo of one that I wired in a few years ago. I mounted so that I did not have to cut the eye off of the original wiring harness (black wire) and used a fabricated jumper lead (red wire) to complete the circuit. Note that the photo was taken during mock up - the thick, red battery cable is not yet attached to the common post.

Post again if you need any more help or ideas.

Mike

[Mike B.]

Re: 57 Battery Gauge Fire (almost)

No problem, glad to help.

It is a scary thing once you realize that with the exception of turning the starter motor over, ALL of the other electrical loads of the car are ultimately carried by that relatively thin (12 gauge?) black wire.

Starting puts the greatest strain on the black wire as the purple wire that is fed from the switch to the starter pulls relatively heavy current while holding the starter solenoid in. It doesn't take long for things to heat up, especially if you "goose it" by using a powerful battery charger with starting boost.

I believe that my link, or more correctly circuit breaker, is rated at 30 amps. That should handle everyday loads; I've never had a problem. More important, it will open the circuit in the event of a dead short which can happen if the insulation gets abraded off of an unfused wire such as under the dash where the wiper cables can act like a whipsaw. This is key to preventing catastrophic fires.

Best wishes,
Mike