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First off, we’re glad comedian Jay Leno is recuperating comfortably after receiving serious burns on his face and hands. He was injured working on one of his vintage steam cars. Probably, the flame for the boiler ignited the gas. That caused injuries to both the left side of his face and hands. We thought we would explain the making of one of these old steam-powered vehicles, and show how easy it can become when you’re mixing steam, gasoline, and an ignition source.

What is a steam car?

Jay Leno
Jay Leno with 1907 White Steam Car | Paul Drinkwater/NBCU Photo Bank

There are few steam-powered cars in existence anymore. Companies like White and Stanley Steamer only produced a thousand a year, maybe even less. And as they fell out of favor, the companies soon were out of business. Any of Jay’s steam cars, and he has quite a few, are extremely rare today. And especially so in running condition. 

The specific steam car he was working on when the accident happened was a 1907 White. These cars use steam pressure to expand in each cylinder. This forces the pistons down, creating power. For gasoline engines, a fuel and air mixture is ignited by a spark plug in the cylinders. This forces the piston down. So that’s the main difference between steam and gasoline power. 

Why did Jay Leno’s steam car need gasoline?

Stanley Steamer
A 1903 Stanley Steamer up Hammer Hill near Cuckfield in Sussex | Gareth Fuller/PA Images via Getty Images

The steam expansion comes from a boiler inside the car, which then directs the steam to the cylinders. Heat for the boilers comes via a gasoline flame. Though the power is generated through steam expansion, the source of the flame is gasoline. 

Somehow, a gasoline spray was sparked by the boiler’s flame, which created an explosion. Gasoline itself is not flammable, it is the vapor spray and fumes that are highly flammable. With the gas spray, oxygen, and a spark or flame, you can create a nasty explosion. 

So why were steam engines used in the first place? First, they were much quicker than gas-powered cars. A Stanley Steamer was once clocked over a one-mile run at 28.2 seconds in 1906 according to the Henry Ford Museum. And they were reliable. 

Has Jay Leno had other problems with steam cars?

White steam car
President Theodore Roosevelt in a 30-horsepower White Steam Car | Hulton Archive/Getty Images

Jay Leno’s Favorite Steam Car Ever Built Is More Powerful Than You Think

But you can’t just hop into a steam-powered vehicle and take off. To generate steam, the boiler has to get hot. It takes 10 minutes or more to get the steam to a point where it can be fed into the engine. Another downside is that it took much more pressure to force the stem into the cylinders. With steam pressure, a gas mist, oxygen, and a flame source, you’ve essentially got yourself a bomb. 

What probably happened was that first the pilot flame is lit, followed by draining the cylinders of leftover water. From there, a valve is opened for the vaporized gasoline to enter the pilot. This is probably how Jay was injured. 

This isn’t the first time that Jay has had trouble with steam cars. He was once pulled over by the police while speeding on the 405 Freeway in Los Angeles. Admittedly, the officer was more interested in the vehicle than its rate of travel. Jay says he never got a ticket for his transgression.