Alex,
Pumping from a static water source, such as a pond, is the hardest thing a fire pump has to do, especially a mid-ship. Since centrifugal pumps, such as your Waterous, do not self-prime, they rely on a second, primer pump to generate vacuum in the pump to start water through. And, as you might imagine, to generate vacuum, every part of the water way has to be tight and leak free. It's more complicated than pumping from a pressure source, such as hydrants, which is, of course, why all city departments use hydrants, and many don't even carry hard-suctions to draft with any longer.
Mike is, again, spot on with his suggestion of back-flushing the pump. There will be lots of rust built up in the tank and pump. You will NOT likely EVER get the rust flakes to stop flowing from the booster tank - just the nature of the beast. Can make spraying through the booster reels and smaller nozzles frustrating, since they tend to plug up with rust. Not a problem when drafting or pumping from hydrant.
Waterous will actually still answer your call about your pump. You will want the model number, and serial number off it, so they can reference drawings about it. I think there's atag on the top side of the pump. Not saying they'll have parts, but just getting drawings can help if needed. The above musters will also have people selling, or even sharing, old pump manuals, if you need that. Typical pump maintenance would include repacking the pump, which, fair warning, is NOT for the faint of heart. Can be a real hassle. Good news is, if the truck drafts ok, it shouldn't need repacking - only if it's leaking like a monster when you pump.
I would strongly suggest checking the pump transmission for good oil, or better yet, just plan on changing it. Drain plug on the bottom, fill level plug on the side, maybe even a dipstick if you can get to it. Uses same oil as your tranny, usually. From sitting, they can tend to collect water in the transmissions over time, good to get fresh oil in there.
I"m a little envious - learning to pump your first truck is a blast! Have a good time, and don't be shy. Lots of help for you out there and here.
-Michael
