oil catch can : what is it for?

[dgrs4sd]

sorry i am by no means an Audi newbie, just bought a 01.5 RS4 body S4 but never heard of the oil catch can

what is the dealyoo?

[NoLeafClover]

im gona try to make this easy. an oil catch can goes on the vacum line that connects from the valve cover to your intake pipe. in our cars if im not mistaken it look like a black round mushroom that comes of the y pipe. from high engine pressure in the valve covers it vents out air pressure into your intake, but with it most of the time oil sips thru from the pressure and ends up in the pipes, thats why sometimes you have oily y pipes and intake pipes in other cars. so in order to avoid oil to pass thru your intake and turbo inlets u use a catch can to act like a funnel to separate the oil and just let the air pass thru. the higher the boost the more oil passes thru. so with time u will need to empty it out before it gets to the level of the vacum lines. hope this helps

[SoEvoL]

used on PCV vacuum hoses, you install two vacuum lines to the catch can, one leads to the intake piping vacuum port one to the pcv valve . As the pcv system works it basically catches the dirty oil and allows cleaner air to be recirculated and please dont use those filter breathers in place of your vacuum hose those = fail, some may feel different, but you need to keep those crankcase contaminated gases removed. You can make some cheap DIY ones or pay 200+ for some name brand stuff.