IH656 Fire

Had quite a scare yesterday afternoon just after starting our 1971 IH656 gas tractor in the barn. Put it in reverse to back it out of the barn and flames just shot up several feet on both sides of the hood. I immediately jumped off and got the heck out of there. Fortunately it slowly backed out of the barn on its own. Still burning as it continued backing it left a fire burning on the gravel floor of the barn below where the tractor was parked and a 50 foot line of burning gravel to where it finally stalled inches from the edge of a wooded ravine. As soon as it stalled the fire on the tractor weakened almost immediately The odd thing about it is the line of fire on the gravel lasted longer and produced black smoke as if oil was mixed with the gas and burned for about 5 minutes. Luckily we got the fires out fairly quickly. Oddly, it appears that the only fire damage was to a few wires on the left side of the engine, not on the fuel line-carb side. No signs of leaking fuel line anywhere between the bottom of the gas tank and carb but haven't taken the hood off yet and haven't looked it over thoroughly. Just restored the gas tank last summer- basically rust inside a few holes on top where mouse nests rusted thru, soldered new steel patches then capped with high heat epoxy just to be safe, We've used it several times since. Someone misplaced the fuel tank lid so I temporarily fashioned one out of uncoated light gauge aluminum flashing loosely crimped over the tank neck above the hood just before starting it yesterday. Could electrolosis between the alum. and steel have caused the fire? It didn't even have time to warm up and hadn't been driven in over a month.

Leaving aside the home-made fuel cap and the repairs, that's why I carry fire extinguishers everywhere; big ones at the barn exit doors, one on each tractor, each lawnmower, each truck.

I'd guess the fire was started by an electrical short when you started the tractor. I'd be wondering where the fuel was coming from that was dripping on the ground. It had to come from somewhere.

You had fuel and an ignition source. Ignition source could have been the distributor or the arcing from the generator or alternator brushes. The fuel was a gasoline leak. Nothing other than gas is THAT combustible on that tractor. To make a fire trail there had to be a major leak. Why did it start leaking that bad after the tractor was started? There is no fuel pump on a 656 gas that I know of. If there is a fuel pump the leak is after the pump and it quit leaking after the engine died. Just random thoughts.

No offense but your fuel tank repairs and temporary fuel cap as described are questionable at best.

The fire pretty much consumed any fuel that leaked out so of course you can't see any leak right now.

your fuel tank "lid" funneled gas down the insides of the hood and found a spark. Be glad you didn't start it and run back to the house for something while it warmed up.

Its easy to imagine the jerryrigged fuel tank lid funneling fuel vapors down the insides of the hood, but not the actual gas. There was a good flow of gas onto the gravel which left a burning trail 50' long.

Think about it for a bit...
Gasoline vaporizes easily, the lighter parts of gasoline do evaporate at room temperature in unsealed tanks. Once you had open flames touching the bottom and sides of your gas tank, it wouldn't take much time for the thin layer of gas in contact with the hot metal tank walls to start bubbling and boiling even if most of the gas in the center of the tank was still cool. Escaping bubbles of fuel all flowing out the small filler hole would also splash out liquid fuel, much like a coffee percolator or a tea pot in a rolling boil.

After the tractor is fixed, I wouldn't drive it without a factory gas cap.

Did a shorted wire burn through a rubber hose? You better go have a look see. If you can't find anything pour in some gas and see where it goes. But before you do anything unhook the battery. And get a correct fuel cap. Good grief, that cap is used on every IH tractor ever built since the F20. And Case IH will send you a brand new one for free.

Gas vapors are heavier than air. Those vapors found a spark (maybe your points?) and ignited. A rats nest on the manifold could have ignited and been fanned by your fan. Your loose fitting gas cap was a very bad idea. Consider keeping a small fire extinguisher on/near your tractor

Every spring wrens build nests on the manifolds of my tractors. If I forget to check and remove them they catch on fire. Turning off the ignition stops the fan and the fire dies down. It's a real heart stopper.