So I installed a PWR radiator as well as a new radiator cap from autozone. The cap will not hold pressure. I can tell the rubber part of the cap is not seating against the inside of the neck. Do I need some sort of special cap?

 

Is that a direct replacement radiator and have you tried your factory radiator cap?

 

Its a direct replacement. I dont have a factory cap, its from auto zone.

 

Well in that case I would recommend picking up a factory radiator cap from the dealership and go from there.