http://en.wikipedia.org/wiki/Cavitation

On 19 Feb 2008 at 10:15, Kenneth Lewis <kdlewis@NORTHSTATE.NET>
wrote:

> Allan,
> It's a mystery to me how a fluid could erode the metal impeller. I stay on
> top of coolant changes so I don't think it was that. I have the distinct
> impression that failure rates did drop significantly when I switched from
> Italian to German made water pumps.
> Ken Lewis
> http://neksiwel.20m.com/
>
> <snip> I have compared a new pump to an old
> >> one. The wear on the impeller blades is very evident . So an
> >> electric driven water pump might prove a healthy gain in FE (fuel
> >> economy).
> >
> > A worn impeller is caused by corrosion and/or cavitation.  Neglecting
> > to change the coolant as specified is often a contributing factor, or
> > it could be poor quality materials in the manufacturing process.
> >
> > Allan
> > --
> > 1991 Vanagon GL
> >
> >

Shawn Wright
http://members.shaw.ca/vwdiesels
'88 Westy 1.6TD 5 speed
'85 Jetta Diesel 1.6NA