As your father and uncle probably concluded, by drilling the hole, they caused a breather/leak that would keep the car from squealing.
On the pcv. There should be an o-ring on the bottom of the valve and then the ring on the cover of the valve with a spring on the cover that holds the valve down and seals the bottom ring. Typically the most likely causes are a missing ring or spring.
Please get a overall picture of the engine/engine bay and post it up. (in case someone also routed/plugged the evap lines or something else odd. Only other thing I could think of is if the lower intake end seal (rubber gasket at the ends of the lower intake manifold were out of place and it was pulling in air from there. Less likely...but yes.. I once managed this feat!
