All primer sealers , primer surfacers are porus , moistuer will penetrate in time . They are not ment for sealing out water or moisture !!!
They are designed to seal off the metal , and other substraits before the final finish/topcoat ,thats what seals everything from water/moisture.

If you can get youself ahold of a MILL guage ( local Jobber may have one to let you use ) , check over the whole car to see just how much material is on it , more then 9 mils is way to thick .
Need to get everything to raw metal , and rebuild it up for a good long lasting paint job !
SprayTech