CHAPTER XXXII
GUARDING AGAINST FIRE
The education of automobile owners and chauffeurs is decreasing the number of cars which go up in smoke, but there still are cases enough to require a word of warning as to causes and prevention. Automobile fires sometimes come from causes not ordinarily considered under the control of the driver. However, a little extra caution in a few matters will render the motorist practically free from danger.
Of course, the principal cause of automobile fires is from back-firing. Without going into all the causes of back-firing, the chief one is too lean a mixture fed to the cylinders. This will almost invariably cause back-fire in starting. Really, the chief trouble comes in starting when the engine is cold, and naturally this is most frequent in the winter. When there is a back-fire a sheet of flame comes from the air intake of the carburetor; if there is anything inflammable in that vicinity, it is quite likely to take fire.
Gasoline vaporizes so rapidly that if there is gasoline in the drip pan there is almost sure to be a sufficient mixture around the carburetor to make trouble. As a matter of fact, the drip pan under the carburetor should be so arranged as to allow any gasoline to be drained off before it has had time to vaporize. Indeed, there ought not to be very much gasoline in the drip pan at any time. If it comes from a leak in the supply pipe or the connection to the carburetor, the leak should be repaired. If it comes from an overflow of the carburetor due to poor seating of the float valve, that should be taken apart and cleaned so that the float valve will seat properly. These two things are practically the only occasion for gasoline in the drip pan.
Another cause of fire may be in running for some time at extreme speed. This usually will cause the exhaust pipe to become very hot, sometimes to glow. The exhaust pipe in some cases is placed close to the woodwork of the car, which may be set on fire. Particularly is this true if the woodwork has an accumulation of grease and oil, and here is where caution will have a beneficial effect. The owner who keeps the woodwork free from oil and grease—cleans it off regularly and thoroughly—minimizes the danger at this point.
The pipe also heats up when the engine is run with a greatly retarded spark. Sometimes the pipe gets red-hot and it is an easy matter to ignite the woodwork. Here again oil or grease would increase the danger. The economical operator will not allow grease and oil to be wasted in this way, aside from the fact that grease, oil, and gasoline in drip pan or carburetor form a menace hard to overestimate.
Fires have been started occasionally by opening the muffler “cut-out” in starting up. This is particularly dangerous when the car is in a garage, where usually there are grease and gasoline spilled around on the floor, giving off fumes and creating a danger zone. Occasionally when the car is standing in the garage the supply line will drip a little. It may be all right when the gasoline is flowing into the carburetor regularly, but when it stands, a tiny drip will make a considerable mixture under the car. A leak, so small as to be unnoticed ordinarily, when continued over night will cause enough mixture to be dangerous. If, to aid the engine, the operator opens up the “cut-out,” there are quite likely to be some sparks flying out. Sparks and gas mixture are a very perilous combination and there is pretty sure to be a blazing car in a moment.
Sometimes in filling the gasoline tank it overflows and drips down. Perhaps the driver, delayed by taking on gasoline, is in a hurry, so he opens the “cut-out” and finds that making haste is often dangerous.
Another cause of fires comes from short-circuiting of the ignition or lighting systems when a storage battery is used. Occasionally a short-circuit will heat one of the wires red-hot and burn off the insulation. Then, if there be an accumulation of grease, oil, or gasoline, there will be trouble.
To obviate vibration, some chauffeurs pack around the battery with used waste, which is more or less greasy. It is possible for a tool to drop down on the battery and give off a spark, or, under vibration, a series of sparks, sufficient to set fire to the waste. It is on record, in one of the old-style cars, that a cushion spring wore through and dropped down on the battery, making a spark every time the spring touched the terminals, and eventually setting fire to the car. The remedy for all these instances is very obvious.