Paul L

There have been a number of threads here over time that describe spontaneous combustion of a Corvette at rest and parked. I recall one C4 that was in a garage attached to a house and basically the house was destroyed. But I have never seen or read an explanation of this problem. In other words why would a sitting Corvette burst into flames? Obviously an electrical short but where?

The NCRS folks give bonus points for a battery disconnect switch and I had one on my 1979 and do as well on my 1967. They say it is a safety matter. What Corvette safety matter are we protecting against with those disconnect switches? Or more importantly what is the flaw in the electrical system that makes this necessary? Look forward to your comments.

Just disconnected my battery for the evening!

BTW, here is the disconnect on my former 1979.






[Modified by paul67, 8:41 PM 5/26/2004]

JRD77VET

Here's the style I use. I can remove the green **** and put in my pocket for "extra" security. The also have a model with an inline fuse for your radio presets.

Paul L

I have that version on my 1967 but it does not answer the basic question!

PRNDL

pretty rare for a vette to sit cold for several days and suddenly burst into flames. I suppose it is possible if, say a mouse gnawed thru a wire and caused a short. I have read that gasoline is the most common source of car fires, but that seems even less likely to be the cause of "spontaneous combustion" of a sitting cold car. Here is my view of one of the greatest risks to our old cars: (I have gone thru this a number of times, but I guess it doesn't hurt to repeat). You are at great risk of electrical fire on a hot day with a hot engine after you shut it down. When the waterpump stops and the fan stops the eingine will superheat. Try this: After shutting your hot engine off on a hot day wait about a minute, then turn the key to the "on" position just to get a reading from the temp guage. You will likely find it way over in the red area. So after you shut the engine off it gets hotter than it was when running, and there may be some old wires a little too close to that hot engine and they can melt causing a short. This could happen anywhere from 1 to 5 or I would even guess 10 minutes after you shut the engine off. If the battery is still connected the short can cause an electrical fire. Anyway, to my thinking that is one of the greatest risks. My garage is inside my house, under the dining room, so I never pull the vette in and just leave it. I ALWAYS disconnect the battery, and almost always pop the hood and look it over for a minute before I run into the house.

NHvette

Not a vette specific reference, but here is a situation that warrants discussion.

My Mercury Grand Marquis had the engine harness pretty tight to the engine.
The vibrations rubbed right through the insulation, and began to intermittently
short against the edge of the block. This took me many many times to find.

However, most wires are fuse protected, so only the battery/alternator wires
are hot enough to start a fire. I think an electrical fire would require Bubba's help.

How about later C3s - maybe have a rusted floor pan and the carpet padding
falling down onto the catalytic converter.

Rusted fuel line or broken hose dripping down on the exhaust in the rear.
I would hope that someone would smell this before a fire.

That's all I can think of. :seeya

Engage

Probably for the same reason people burst into flames.

:reddevil :reddevil :rofl: :rofl: :leaving:


[Modified by Barry, 9:20 PM 5/26/2004]

Sigforty

I would go with a critter of some sort making there way into the wiring.

LAvetteman

The only part of this I disagree with is that I feel certain an engine will only get about 5 degrees hotter after shutoff versus when it was running.

Back to the question at hand. Any car at any age can develop a short depending on where and how its wires are ran. Sure its super rare on a newer vehicle but the older a vehicle gets the better the chances are of a short happening. Age causes two things to happen to wiring. Sagging of wires due to heat and movement. And deteriorating of wire insulation.

PRNDL

Actually, that's the only part of my story that I AM certain about!! :lol: Try it sometime on a hot day; Shut the engine off with the guage showing 210, then keep the key turned to the "on" position and watch the temp guage move to the right, into the red area. When I was a teen I remember blowing more than one radiator hose AFTER turning the engine off. Notice that many modern cars have electric fans that keep running after you turn the car off for this very reason. Anyway, very simple thing to try..... :)

w1ctc

Anything powered when the car is off can cause a fire. When my C2 clock
quit it was due to the wind up soleiod shorting out and burned up. If the
clock case had been plastic, it could have caught fire. The fuse didn't blow.
Improperly wired after market gear could be the cause of a lot of fires.

Another thought, how many of us think about checking if the right size fuses are in the right places? Disconnect is the way to go but if I had a irreplacable
collector car in the garage, there would be a CO2 fire suppresion system.

Paul L

The clock is one of my concerns although this one is quartz. Nevertheless I still use the disconnect.

427basketcase

The engine temp will continue to rise after operation until the entire block reaches a uniform temperature, then it will cool as a mass. This is known in the industry as Heat Soak.
The automotive industry has known about this for decades and that is why newer cars will continue to run the cooling fans long after the engine is shut down. This is taking advantage of a phenomenon known as Thermosyphoning, where the hot coolant in the engine, being less dense than the cooler fluid in the radiator rises to the outlet and flows into the radiator. As the coolant gives up heat to the air and cools, it moves downward and back into the engine. This will continue until there is no temperature difference between the radiator and the block.
Our older cars do not run the fans after shutdown, and that is why the temp will spike shortly after the engine is shut down and stay that way for quite some time.
This is not the cause of spontaneous fires, however it will contribute to another cause, i.e.: fuel leak, shorted wires etc.
Just my $.02

LemansBlue68

My bet is that many of these cars (pre-'69) had mechanical voltage regulators. If a contact were to stick in the charge position when shut off, it becomes the discharge position. The battery discharging back through the electrical system could generate the kind of heat necessary to melt and burn wires, and MAYBE your prized four wheel possession.

Just my theory anyway...

These discharge switches are cheap insurance, regardless. I saw them all over at the spring Carlisle for $2-$3. Even you have to pay $20, it's still cheap insurance. If you want to keep your clock going, install a 5A fuse in parallel with the switch. If any battery discharge exceeds 5A, the fuse burns rather than your wiring. Just don't forget to switch the cut off to the ON position before hitting the ignition or your fuse will blow.

Paul L

That's an interesting observation that I had not thought of! They are indeed mechanical and adjustable.

gkull

Here's what I have. Since it's a key I can take it out of the car as a anti-theft divice Also no more battery drain when I don't fire up the car for a month. I do have a little auto trickle charger and now I don't have to worry about using it anymore.

Has any body tried one of these? I used to have a rotary type and was never happy with it. It couldn't handle the amps and died years ago from internal arcing. So I removed it. I have been thinking about a Knife switch in the battery box, but it is so hard to get to with a non-folding racings seat and roll cage.
This key thing could be installed on the passenger floor, near the seat and consul for easy access from the driver seat in case of emergency. Also it's a theft deterrent.
http://www.jcwhitney.com/webapp/wcs/...X&appId=466344



[Modified by gkull, 12:58 PM 5/27/2004]

JB

Yup, that's the switch I use, and it's by far the best I've ever had. I'd tried the blade ones, the **** ones, and even a toggle switch spliced into the coil wire. This one is bulletproof, convenient, and the key is removable for security. This particular setup was offered as an option on Volvos, and it consisted of the switch and two seven foot long heavy duty battery cables, most of it covered in very heavy duty shrink tubing. I've got it mounted in the engine compartment along over the wheel well. They come up on ebay quite frequently. I paid $8 for mine.



[Modified by JB, 1:46 PM 5/27/2004]

markdtn

To answer the original question: The wiring is pretty tight above the speedo/tach against the dash. Wires can lose insulation and sit aginst fiberglass and if grounded cause a fire. These wouldn't happen sitting still but fuel could. The fuel tank sending unit can leak on the 74 back cars and a gas water heater can ignite the vapors.

Thumper76

JB, what do you call your battery disconnect switch when searching for it on eBay. I really like that setup and wouldn't mind picking up one for myself.

Thanks,

Jeff

rob75383

I had a "small" fire under the hood, back in about 2000 or 2001.
I had just installed a new trans cooler, and test ran her in the driveway for about 25 minutes checking for leaks. After I was satisfied she wasn't leaking, (or soI thought) I drove about 10 minutes to autozone in Schaumburg to see a vette guy who worked there. I parked the car, went inside only to find that he had left early.
I spoke to another dude there, and was going to show him my car. I was inside for about 5 minutes. I then went outside, opened the hood, and the dude was admiring my detailed engine when his manager (who was changing some guys taillight) told him to go back inside since they were the only two working, and someone's gotta man the phones.
Another minute passes, and the manager comes over to admire my engine. After answering a couple of his questions, we saw a flickering red reflection on the freshly painted engine compartment. Before the manager could start yelling, "FIRE!!! Dude! FIRE!!!" I was already reaching for one of my three extinguishers that I keep in the car. I went over to the passenger side to see that my header wrap had caught fire, and the flames had already engulfed the entire lower area of the header. This was dangerously close to the fuel pump and fuel lines.
With a quick spurt of the extinguisher, I had the fire out, plus I had a nice coating of white powder over every surface of the motor (luckily it wasn't running!).
Turned out to be that the trans cooler line developed a leak under high pressure. I double clamped the hoses, wiped the motor down, and cleaned up much of the white powder.
Luckily for me, there was no damage whatsoever, minus the white power residue all over the body and engine.

What amazes me is that it took about 10 minutes for the flames to ignite.
I'd imagine that the headers would have cooled off by then, but then again, maybe the aformentioned heat soak transferred enough heat to the headers to ignite the tranny fluid.

I've yet to install a batt disconnect, but I do remove the cable from the battery most of the time.
And, YES, I still have my header wrap on, and no other fires...
As to how a vette that's been sitting for a week could catch fire, I would have to guess that either it was electrical, or deliberate tampering.

JB

Here's one, though the cables are shorter (different model car maybe?). It wouldn't be long enough to mount the way I've mounted mine, but would work as an inside the car switch. Can't beat the price--current bid's only a buck with only 18 hours left in the auction. http://cgi.ebay.com/ebaymotors/ws/eB...category=33574

JB


[Modified by JB, 11:09 PM 5/27/2004]