Causes of excess blowby

[Badger]

cm870-
ive had this truck since 850k miles, now has 1.4mil .
Has had 2 set of pistons/liners put in since i bought it, and it has always had quite a bit of blowby. can a wore out air compressor create blowby ? i dont even pay attention to it anymore but after holding the steering wheel all day today i just started thinking about it...

and i made one of them test tube things like in the manual for checking blowby pressure, and mine was always worse than they say is "acceptable"