spectra premium heater core issue ? / anyone recommend a good heater core ?

"Cheap Chinese Chit happens" LOL! no really, O'Reilly, Auto zone, Advance auto sell cheap stuff, but that's what their customers want. Some items I will buy there knowing they may last only a year. I accept it because its cheap. If I want better I go elsewhere and pay more. I have learned that some parts you don't go cheap on. OP, I would try another Spectra Heater core, if you get two in a row, then bail on them . Its probably an isolated case of a defective unit. there is a blockage inside it from manufacture.