The vanilla ice cream mystery
This story circulates. It may be true but it has the flavour of the urban legend. It’s a good story, though. Thanks to Jim Lapic for this version.
For the engineers among us who understand that the obvious is not always the solution, and that the facts, no matter how implausible, are still the facts …
A complaint was received by the Pontiac Division of General Motors:
The Pontiac president was understandably skeptical about the letter, but sent an engineer to check it out anyway. The latter was surprised to be greeted by a successful, obviously well educated man in a fine neighborhood. He had arranged to meet the man just after dinner time, so the two hopped into the car and drove to the ice cream store. It was vanilla ice cream that night and, sure enough, after they came back to the car, it would not start. The engineer returned for three more nights. The first night, the man got chocolate. The car started. The second night , he got strawberry. The car started. The third night he ordered vanilla. The car failed to start. Now the engineer, being a logical man, refused to believe that this man’s car was allergic to vanilla ice cream. He arranged, therefore, to continue his visits for as long as it took to solve the problem. And toward this end he began to take notes: he jotted down all sorts of data; time of day, type of gas used, time to drive back and forth, etc.
In a short time, he had a clue: the man took less time to buy vanilla than any other flavor. Why? The answer was in the store layout. Vanilla, being the most popular flavor, was in a separate case at the front of the store for quick pickup. All the other flavors were kept in the back of the store at a different counter where it took considerably longer to find the flavor and get checked out. Now the question for the engineer was why the car wouldn’t start when it took less time. Once time became the problem — not the vanilla ice cream — the engineer quickly came up with the answer: vapor lock. It was happening every night, but the extra time taken to get the other flavors allowed the engine to cool down sufficiently to start. When the man got vanilla, the engine was still too hot for the vapor lock to dissipate.
Moral of the story: even insane looking problems are sometimes real.
This page was last updated September 1, 1998.