Roland,
I haven't looked for a new pump for a while, but I only use the cast iron
scroll impeller style of pump. Your concern with your old pump may or may
not be well grounded. The seal surfaces are of the spring loaded graphite -
ceramic type, not elastomeric, although the seals typically have an
elastomeric perimeter seal. If left undisturbed, without corrosion, it may
be fine. It will take more than twisting it by hand to tell its condition.
Most pumps, not destroyed by corrosion are rebuildable. It take a good
press and some fixturing to accomplish, but it can be done. Seals are
common, and very generic. The biggest problem I've had is removing the old
impeller. I always end up breaking them, but I've only done a few. As far
as I know, the Motorsports impeller is still available so the easiest way to
get this style of pump , if you can't find one in stock, is to buy the
impeller and a pump with a stamped impeller, remove the stamped impeller and
push on the cast SVO impeller. You also get to set the clearance of the
impeller to the casting, and reducing this clearance makes the pump more
efficient. You couldn't get me to run one of those stamped things.
BTW the theory behind this reverse scroll impeller is that the pressure of
the water behind the blades is not reduced as much as it is with radial
blades. When the local ( behind the blades) pressure is reduced to the
point that the coolant can boil (remember, pressure increases BP, reducing
pressure reduces BP) steam pockets (cavitation) form in the coolant. When
you looked at your front cover and saw the pitting in the aluminum behind
the pump, much of what you saw was the results of cavitation.
Tom Hall
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