Chrysler Sebring Radiator Leak

Hello....i Have A Problem That Has Baffled Me More Than Any Other....2004 Sebring 2.7l V6...replaced The Water Pump Less Than A Year Ago......

I Had A Engine Rebuilt With 25,000 Miles On It Everything On Engine Brand New, Struts, Once Enegine Put In Car Stated Running Hot After...

Had A Radiator Leak, Sealed It With A Stop Leak. Weeks Later Radiator Stopped Dripping, So I Went With A New One, Now I Have No Leaks, But...

Im Getting Presure Build Up Even Tho I Have Taken The Thermostat Out Presure Still Builds Up The Radiater Does Have A Small Leak But It...