A few days ago I was driving home in rush-hour...

Dear Car Talk

Dear Car Talk | Jan 01, 1994

Dear Tom and Ray:

A few days ago I was driving home in rush-hour traffic, heading down into a nearby canyon, when my previously reliable 1983 Olds Delta 88 suddenly roared, and the engine started racing. It speeded off on its own free will, carrying me along with it. My brakes failed, my parking brake was of little use, and I finally stopped by throwing the transmission into Park (after exiting the freeway and slowing down by going up a hill). My mechanic, who had a day earlier told me I needed a carburetor overhaul, said a clogged carburetor had caused the problem. It's overhauled now, and the car drives normally again. But I want to know, was this a freak occurence, or does this sort of thing happen to people who put off overhauling their carburetors until their next paycheck? And in the future, what is the best way to stop a runaway car?

TOM: Great questions, Jan! I'll bet that was the most exciting afternoon you had all week!

RAY: Your mechanic's explanation is not quite right, Jan. I don't think anything was "clogged" up. My guess is that the secondary throttle got stuck in the open position. This carburetor has two throttles; one that's connected to the gas pedal, and a secondary one that opens when the engine reaches a certain speed. Your secondary throttle probably opened at high speed, and then got stuck in the open position because the carburetor was all gummed up. And that's what made the car "run away from you."

TOM: And that IS an unusual occurrence. So if he diagnosed it properly, and cleaned up your carburetor, it shouldn't happen again.

RAY: But if you are ever driving a "run away car," here's what you should do: Immediately put the car into Neutral. You say your brakes failed, but my guess is that they just couldn't overcome the power of the engine. If you "disengage" the engine by putting the transmission in Neutral, you ought to be able to bring the car to a safe stop by using the brakes.

TOM: If you were to turn the ignition off, like some people are tempted to do in this situation, you would not only lose your power steering and power brakes, but you run the risk of locking up the steering wheel by turning the key to the
"lock" position. So leave the engine running and the shifter in Neutral.

RAY: The only danger is that the engine might be damaged by racing so fast. But in that situation, who cares? I'd be more worried about YOUR well being than the well being of the engine. And besides, it'll probably be fine. Just pull over as soon as you safely can, stop the car, and shut off the engine. Then say a few Hail Marys and call the tow truck.

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