no water flow, engine overheats

[shawnb]

This is a continuation of my rebuilt engine install.

Well, I made progress today and installed rebuilt A4 in boat. The problem is no water flow in exhaust. White vapor steam coming from exhaust.
During the rebuild I replaced the water propeller and cleaned pump.
Raw water is making it to pump and water is in engine block. Here is the newbie stuff I did when installing the engine and possibly causing what appears to be a failed water pump.

Started engine but had exhaust valve turned off. Engine was hissing and blowing and probably created a lot of back pressure. turned on valve and exhaust, Yippie but no water

Thought blockage might be thermostat(I tested this before installing)So I flipped it over. I thought this fixed problem...water started dripping out...very low flow. one note: when I flipped thermo over and inspected head it was bone dry in cavity.

Not enough water, so I removed thermo completely...........no success.

My question now is: could I of cause a vapor block or airlock by not having exhaust valve and thermo in correct position? And once corrected now have no water flow?

What steps do I take to get water flowing and engine temp correct?

How can my water pump fail? The only wear part is propeller and this is new?

Also, I ran the engine for probably 15 minutes....not realizing my 220-240 degree engine temp issue)newbie).......have i damaged the engine now?

After engine cooled a number of times it started right up but not under load.