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The Empty Brake Fluid Can

The Puzzler


RAY: "I asked her one question, and when she gave me the answer, I knew what was wrong with her car." What was the question?


TOM: Mmmm.


RAY: And the question was: How often…


TOM: Do you replace brake fluid?


RAY: Do you add brake fluid?


TOM: Yeah.


RAY: And the reason he asked that question was this. Somewhere along the line, he surmises she went to the gas station and her brake light was on because the fluid level was down.


TOM: Mmm-hmm.


RAY: She buys a can of fluid from the attendant and watches him fill up the reservoir. Figuring this is part of the regular maintenance of the car, whenever the light goes on she tops it up, never bothering to ask, "Where's the brake fluid going?" It's like, well, you add oil from time to time. And she was constantly adding brake fluid to a leaking master cylinder. And the master cylinder was leaking into...


TOM: The booster.


RAY: The power-brake booster. And every once in a while, when she came to a stop, especially an abrupt one, or if the level of fluid in there--where there's not supposed to be any--was high enough, that fluid would get sucked into the engine and make the thing try to combust the brake fluid, which would cause it to stumble and choke and maybe even stall. And then, once it worked its way through, accompanied by this belch of smoke out the tailpipe...


TOM: It ran like a dream.


RAY: Everything would be right. And the subsequent stops wouldn't be a problem, because she'd have to wait until enough fluid accumulated in the booster to cause the problem again.


TOM: Oh, man! That's very good!


RAY: So the question was: How often do you add brake fluid to the car?


TOM: Yeah!


RAY: So, who's our winner?


TOM: Nathaniel Meyers from Berkeley, California. Congratulations!

[ Car Talk Puzzler ]

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