K here's the story. I got a 96 teg ls. It's been getting hot recently so I have my mechanic check it out. Turns out there's no circulation, the top hose is getting hot as hell and the bottom staying pretty cool, maybe slightly warm. So he said it could be the rad. or the water pump. So I buy a new rad before the pain in the ass water pump and he puts it on...still no circulation. So he's saying it's gotta be the water pump unless the head gasket has a small leak which he think's is unlikly because the car is running real smooth and there's no white smoke coming out the exhaust. So basically I'm just asking here what you all think before I go and replace that water pump since it's a pain in the ass to get too so it'll be pretty pricey to fix. Any other ideas?

EDIT - Forgot to mention a brand new thermostat was put in too and working properly so it's not that.