Steve, we are making the same point from different perspectives.  I have
honestly not heard of, nor would I consider replacing only part of the water
pump for anything but a roadside emergency.  Yes, it's pain, but that's the
price of being thorough and sure of the repair.  I have also seen this
deterioration on other brands of vehicles with aluminum water pumps.  Some
were so bad that the hose barbs were nearly eaten away.  It's a wear part.

BTW, Bus Depot has the '83 diesel hoses.  The prices are scary enough to
make you forget all about water pumps.  Do you have an "83 diesel?

Mike Snow

<< IMHO, this is really a non-issue.  If a water pump shaft seal lasts long
 enough for cavitation to cause erosion on the pump impeller, you have
gotten
 you money's worth from that particular pump.   >>

 AH! yes indeed..except most people don't replace the pump they just replace
the face plate and impeller. the housing (the WHOLE pump) is the part that
wears. It's the BACK of the pump, the aluminum part on the block, NOT the
iron/steel impeller!
In it's life the van may have had 5-6 pump "faces" on 2 or 3 different
engine
blocks..all with the same housing!...So, my point, if I may reiterate, if
you
have reason to have the engine our or apart enough that the pump housing is
accessible ..it's time to replace the pump and if you are JUST doing the
face
plate and impeller, CHECK the housing!