In a message dated 1/28/01 8:32:25 PM Eastern Standard Time, NotaJeep@AOL.COM
writes:

<< It's the BACK of the pump, the aluminum part on the block, NOT the
 iron/steel impeller! >>
 Err..OK..wait...cavitation..the pump "sucking" the coolant in causes the
presuure to drop..the low pressure causes localized reduction in the boiling
point of the fluid and it flashes to vapor..this creates vapor pockets that
form and collapse..this causes what is known as "fluid hammer" and it
actually knock little chips and chunks out of the metal in the back of the
pump (and the impeller too, but it's stronger) The long term effect is that
the back of the pump gets thinner and thinner until it's breached..and out
goes gallons off your precious coolant (we're FREEEEEEE!) and your head goes
"Terwoink" and warps off the block....(I swear the cover under the engine is
to contain the shrapnel!)
This whole thing is worse in the vanagon dues to it's higher pump speed and
higher coolant temp

High performance boat owners know all about this..one of the big deals with
stainless props is that they don't appear to "rot away" as fast when hooked
to some big block chevy that has them cavitating all day long.....

steve

"Hey! nice Jeep, Mister! "
"Look kid, it's NOTAJEEP! "