16v Airbox

Hi all.

First post on the forum. So far I've just used the search engine to answer all my problems, but I can't find an answer to this one.

51 plate, 16v 1.4 Fabia, AUB. The usual problems: did have excessive oil usage until I cleaned the crankcase breather (not the £800 ring repair that the stealers wanted to do) and the power steering sensor needs replaced.

My question is; the rubber pipe that feeds into the airbox from the crankcase connects to a plastic internal pipe. Just inside the plastic pipe is a small rubber washer behind a plastic crossbrace. This rubber washer has perished and has gone. Is the washer required to maintain a certain amount of back pressure or can the airbox run fine without it? There is still some oil getting into the airbox so I'm scared that if too much gets in, then the TB will get choked. What do people with induction kits do with the crankcase breather and any oil that blows up it?

Thanks in advance.