[crooster]

In the 944 world it's pretty common practice to replace the waterpump every other timing / balance belt change, some do it every time. But on a 944 a seized waterpump can take out the timing belt and being an interference engine, bad things happen.

My only direct experience with a Boxster waterpump failure on a friends car was that it gave lots of warning - noise, then leaks. In that case I guess the bearing seal failed rather than the impeller.