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Richard Casady

On Thu, 29 May 2008 13:16:00 -0400, wrote:

On Thu, 29 May 2008 16:33:20 GMT, (Richard
Casady) wrote:

On Thu, 29 May 2008 06:07:12 -0400, wrote:

A car doesn't have to suck up water from an outside sorce to
lubricate the water pump. It can be run dry a lot longer than the one
in your outboard.

That's an understatement. There is no contact between the impellor and
the housing, and they can be run dry approximately forever. The engine
on our jet boat doesn't even need a water pump. Water is bled from the
drive.

Casady

I was always under the impression that automotive waterpumps gleaned a
bit of lubrication for the shaft and seals from additives in the
coolant. I agree that the impeller in an automotive water pump is
completely immune from being run dry, but I'm not so sure about the
shaft and seals. I think they will take quite a bit of abuse, though,
unlike the very different situation for an outboard water pump
impeller which will be ruined almost instantaneously if run dry.

I said approximately forever, when I meant not much damage before the
engine melts, and you are right about lubeing something else, not the
rotor. I think glycol coolant comes with that additive, but I am not
sure. Glycol is a better lube than water.

Casady