Can I pull the stat cover off, run the motor to see if water is flowing from the ports? or would water just gush out?
You can, but there will be a lot of water gushing as you suggest. But look closely, and you will see water coming up through the hole that aligns with the gasket hole, AND also a smaller hole down in the side of the thermostat chamber (the upper yellow arrow in mumbles great picture)..
