RAY:This was from the Crusty series featuring our beloved old mechanic, Crusty, and here it is. Some years ago when Crusty was in our employ and still in possession of his faculties, we had a schoolteacher who had taken his car to us and on which we'd done a lot of brake work. Anyway, he came in one day and said, "Guys, I'm kind of disappointed. I usually just drive back and forth to school, but now that the academic year is over I've been doing a lot more long-distance driving especially on weekends and I've noticed that if I'm driving on the highway for any extended period of time, when I get off and I use the brakes they're often not there, I lose them. I step on the brake and it sinks to the floor. It's a little scary."

So, as you would, to placate the customer we put the car on the lift and we pull off all the wheels, and of course we had already sold him a master cylinder, calipers, wheel cylinders, brake shoes and all that, so we couldn't do that again. So we combed over this thing looking for a collapsed brake hose or anything that could possibly have caused his problem. Anyway we're going over to look if anything is wrong and we see nothing, everything looks fine, and everything is fine with the brakes. This whole time Crusty is just sitting there in the inky shadows mentally counting his teeth wondering how much longer he'll be able to eat corn. Anyway, after we concluded that there was nothing wrong with the brakes Crusty asked the customer, "When did you have the exhaust system replaced?"

"Oh," the fellow says, "Jeez, as a matter of fact I did have the system replaced right before the end of the school year, and I took it someone else because you thieves wanted to charge me too much."

Crusty says, "Well, that's the problem." So the question is, what's the problem? How could replacing one's exhaust system cause the brakes to fail?

TOM: And how did Crusty know?

RAY: What Crusty knew was that we had eliminated everything else. And without even looking, he knew that the people who put the muffler in the exhaust system had done something awful. They had put the exhaust pipe touching one of the brake lines. Now exhaust temperatures can run upwards of 500 degrees. And brake fluid boils at something less than 300 degrees. This was a recipe --

TOM AND RAY: For disaster.

RAY: So when he drove the thing, it sustained high speed in the summer. The exhaust system got that brake line really hot and the brake fluid turned into a vapor and made the pedal sink to the floor. And, of course, by the time we got the thing, everything was cooled off and worked normally. But when it was

hot, it would fail because the brake fluid had turned to vapor. TOM: And, as we know, vapors are compressible and liquids ain't very.

RAY: Who's our winner?

TOM: The winner is Regina Warren from Suffern, New York.

[ Car Talk Puzzler ]