Sorry in took a while to get back, iboats isn't notifying of a response and if you forget to subscribe to a thread (like I did) you don't know either.
Back to your issue; the garden hose connecter is using muffs, and that's good. Since you changed the impeller after the old one came apart your problem could be from all the pieces left behind of the old one. When you replaced the impeller did you find all the pieces of the old one? If you didn't need to go inside the boat and disconnect the hoses and back flush them until all the pieces are found. Those pieces usually get caught in the power steering cooler or thermostat housing
