Yup. It's the water pump for sure.  I listened to it as per Joel's 
instructions with an aluminum tent pole (isn't that what you said? <smile>).
Rattles like a son-of-a-gun when you hit any of the metal parts connected 
to the water pump, but smooth as silk on the head itself.
Bought a new pump, and now I have to get up the nerve and time to put it 
in....

--
Gerry
Gerald Skerbitz <gsker@lenti.med.umn.edu> U of MN Med.School.Admin 6-5379