oil in aircleaner

:trink39: hi all, im looking for sum help on a 12 hp brigs motor i just got. 1st of all the motor runs great, no smoking or rough runing. that being said the problem im having is oil is coming outa of the tube that comes from what looks kinda like a pvc valve to the air cleaner. i use to have a 8hp that did the same thing, a friend told me i needed a valve job. is this the case or is there another simple fix for this? i dont know if its a pvc valve or not for sure but you can take it off and inside you can see the valve stems. thanks for any help