Mort's Tune-Up

Mar 19, 2022

This is the right season for this puzzler, and that's a hint actually. So pay attention. This particular car, I think can be a lot of different cars, but for the sake of this puzzler, it is a 1980 Chevy Malibu. Okay? And here's what happened. A fellow had the car tuned up at his local filling station. They had Mort tune it up.

"Hey Mort, throw a tune-up into this!"

So Mort tunes it up. And a few weeks later that the customer comes back and complains to Mort. He said, "Gee, since you tuned up my car, the brakes don't work." He says, "What do you mean the brakes don't work?"
"Oh, I don't know. There's something funny going on here. I step on the brakes especially  now that there's a little snow on the ground, I stepped on the brakes and the car doesn't want to stop."

And of course, Mort says that it's impossible. "What could I possibly have done in tuning it up that would affect the brakes like this?"

So they take it out for a test drive. And of course, it's a nice dry day, the roads are dry. And Mort says, "there's nothing wrong with the brakes, you're nuts! Nothing wrong with the car at all!"

And sure enough, a few weeks or days or months or years go by, and the customer takes the car back in again on a slippery day. And Mort drives the car again and he says, "Oh, that's it."

So sure enough, Mort did something wrong. But the question is, what? What did he do wrong? And for extra credit, why didn't he notice it the first time?



So what did Mort do wrong?

Well, Mort was a little bit disappointed that the car ran badly after he did the tune-up. And he didn't feel entirely justified in charging the $285.19 that he was going to charge. He thought it should run more smoothly.

So what he did was he turned the idle speed up, the idle speed is supposed to be like 800. And he found out that when he turns it up to 1100, it ran like a dream. So what happens to the driver of the car, I mean, because this is a rear-wheel drive car that has very little brake pressure going to the back wheels, because the RPM is higher, there's more power going to the wheels. So when he steps on the brake, the front wheels stop or at least try to stop the car. But there's not enough braking action to stop the rear wheels. And that's why it feels funny like something's wrong with the brakes. They're just slipping and the car's fishtailing it's all over the place.

And you wouldn't notice this on dry pavement because it would stop pretty well. In fact, you'd be delighted with the tune-up because it would be like a dream. It just doesn't stop. So he had to turn the idle down and it ran just like it did when he brought it in.

Even if your old car doesn't start, it can start conversations that will help all of us learn more about the world. Donate your old car to your favorite NPR station. Here's how.  



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