Volvo 5.7 Overheating Problems. Pulling my Hair Out!

[Steigers]

I installed a new impeller in the raw water pump while I was winterizing, the old one was missing vanes, I think I found all the pieces in the thermo. Now I am having overheating issues. I hooked the muffs up and ran it, no water out the exhaust and it overheated. I took it to the lake and it overheated in water. I am unsure which port on the pump is intake and out to the thermostat. The book says intake on top, out to thermo on bottom. This appears wrong to me by the way the hoses are laying and fastened, and the direction of the vanes of the impeller. Could someone with this exact engine confirm which port is intake/out to thermostat? I switched the hoses according to the book, lubed the impeller, it still looked great, hooked to the flush intake, water came out the outdrive inlet then the exhaust and never overheated on the trailer. I unhooked the flush and tightened the plug with channel locks, hooked up the muffs and it overheated again, no water out exhaust. I noticed a small leak on the pump port hose swivel. Is this repairable? I also noticed a groove on the inside front flat part of housing from the impeller. My thoughts are that the housing is worn and my new impeller is not sealing against the flat side, the swivel is letting air in, I have hoses backwards, or the whole pump needs replaced (I hope not) The boat is a 2004 2400 with 470 hours, no salt water. Any help is greatly appreciated and I hope to pay it forward in the future. Thanks for any
advice! A couple pics for clarification.

 

[Sparkinator]

Have you tried it without the thermostat just to eliminate that as the problem?

 

[dannys2004glastron175mx]

Top hose is intake

 

[BRICH1260]

I had the same problem once. Found out I had two O rings on the pump and it was not sealing and sucking air. The pump would not push enough water up to the thermostat housing. While on muffs disconnect the thermostat intake water hose from the thermostat housing and start the engine. Water should shoot up several inches if the pump is working properly. turn engine off quickly to avoid overheating. If water does not come out under pressure, you have some sort of pump issue.

 

[Thalasso]

I had the same problem once. Found out I had two O rings on the pump and it was not sealing and sucking air. The pump would not push enough water up to the thermostat housing. While on muffs disconnect the thermostat intake water hose from the thermostat housing and start the engine. Water should shoot up several inches if the pump is working properly. turn engine off quickly to avoid overheating. If water does not come out under pressure, you have some sort of pump issue.

Common problem