On Tue, 23 Dec 2008 13:36:57 -0000, John Weston
wrote:

In article lutions,
says...
I'm going to be hauling soon, and even though I have realitively easy access
to the raw water pump/impeller, I'm thinking of replacing the cover with a
Speedseal. It seems quite simple to do it, and then I'd be able to deal with
a problem without fumbling for a tool. The impeller is due to get changed
anyway, so while I'm there... for reference,
http://www.speedseal.com/speedseal.html.

Has someone used this product? What do you think?


Yes, I've had one for some years now and it lives up to its name. It has
the main advantage that it is easier and quicker to remove, not needing
tools and, because it has holes and slots, rather than all holes, is
less likely to get dropped when being refitted. (Two screws remain in
the block so it can be relocated without seeing where the screw holes
are.) It also uses an O-ring rather than a gasket for sealing. This
lasts much longer and is less likely to be damaged.

What I'd like is a Speedseal with a window, so I could check the
impeller is rotating :-)

Anybody know how raw water pumps performed before impellers
became synthetic?
Not having a boat, but having plenty of experience with pumps, it
strikes me as odd that engine cooling should be such a dicey
proposition.
I can understand the rubber impellers on OB's, which can't be
practically equipped with the filters some have posted about here.
The biggest argument for them I've seen is the vanes giving way to
twigs and other detritus. Don't the canister filters I've seen here
keep this from getting to the pump?
Corrosion resistance is another argument, but there are metal alloys
that do well at that.
Then there's price. Which I suspect is the real seller.
I did look a bit on the net for metal impeller raw water pumps, but
what I found were electric motor powered, maybe intended for ships.
It seems that with decent filtering a metal impeller pump would be
more reliable in protecting an expensive engine.
You mentioned knowing if the impeller is turning.
Can't a pressure gage set be attached to these pumps, perhaps with a
low-pressure alarm or engine shutdown?
It just seems very odd to me that so much is left to chance.
Weather I can understand. A blown engine because of an inoperative
impeller is more difficult.
On the surface it looks like sailors have no mechanical aptitude, and
are getting suckered by "accepted practice" regarding engine systems.
But I don't believe that, so I'd appreciate some instruction from the
sailors here as to why this "diciness" about engine cooling exists.
I started to say these "plastic" impellers suck, but unfortunately it
appears that might be praising them.
Thanks!

--Vic