[Corts60]

That is not called a blow by filter. That is just a breather tube that vents the crankcase into the air cleaner. The PCV valve is probably on the other valve cover and that needs to be connected to a vacuum source, usually the bottom of the carb. The mechanic should know about that.

If he is saying there is blow-by then I would ask what the results are from the compression tests he did to verify it is blow-by causing the gaskets to fail. And if he did a compression test, ask if he put oil in the cylinder and re-did the test to see whether or not it is the rings that is causing the blow-by.

Sorry if that seems like a lot but it is necessary to determine what is the proper place your money should be spent.