Question about weird recurring specific searches

[Prometheus]

I've been seeing one or two of the top traffic keywords come up very strange looking in Google Analytics. Anyone have any ideas?

Here's an example for the top five search keywords:
Source | Traffic | % visits
- cars | 5,000 | 18%
- trucks | 2,000 | 12%
- vans | 1,850 | 10%
- How to change the water pump on a 1999 Chevy suburban | 1,250 | 8%
- vehicles | 950 | 5%

It's clear that there are a lot of users that will type in cars, trucks, vans or vehicles. But, there is no way that many users are typing in "How to change the water pump on a 1999 Chevy suburban". Did this get cached somewhere? Is this a link that got put into Ask.com or into Wikipedia somewhere so that when it's clicked it gets pushed through to Analytics as if each user typed that phase into Google?

Thanks in advance!

[SemAdvance]

Actually it very well could have been a long tail search query.

Google wrote in one of their blogs recently, that each week they see millions of keyword queries they never saw before, and each week they see keywords no longer being used....

Nothing more than the state of search in the 2000s...

As for the percentage amount... that would seem to indicate the term is an anchor text link somewhere in Googles network.

[cbosleeds]

Sometime search results like this can even be the result of a classroom style call to action, where there is an exercise either in a live or a web tutorial which involves searching for a certain term on Google - this seems like a number that's too big for this to be the right explanation in this instance though