Just a check valve, not in the valve cover, but in that plastic hose, only lets piston ring blowby enter the inlet of the turbo. With the major problem of burning carbon in the gas. One gallon of gas, 6 pounds, has 5.5 pound of carbon in it.
For years, been tossing in a can of Seafoam om a full tank of gas, about every 3K miles to help keep that engine clean. Not even sure why this stuff has to be returned to the combustion chamber, builds up carbon not only on the intake valves, but the face of the injectors as well.
Even after all of this, but returning that hose to the inlet of the throttle body, built up carbon on that throttle vane, causing it to stick. When I took my foot off the gas, the engine was still revving. Had to clean that off with choke and carbon cleaner, but did last about 35 K before this happened.
When they first came out in the late 50's, was returned to the base of the carb, so only problem was carbon build up on the intake valves. Really no definition on what top tier gas is, suppose to have the cleaner in it.
Is a venturi in the turbo input that creates a vacuum to suck blowby back into the engine, guess they have to do it this way because of the AIC and emission control, but is a problem. Ha, rather put it in a can and mail that to the EPA.
Was very welcomed back in 50's, use to use a breather pipe that would suck up road dust when you took your foot off the gas, need a shovel to clean out the sludge and the engine was loaded with it.
82 454 has one, some guys said to just shake it if it rattles okay, I blew into one end of it, should be free, other completely blocked. If leaked, just blow in some choke and carb cleaner than slap it back in. But just checking on a new one, only a buck fifty part.
This is the one in the Cruze, I see they brought the price down, use to be a 70 buck part, but now only 44 bucks.
Also a pressure sensor in these cars, if you don't hit about 15"/Hg measured at the dipstick tube at idle, will generate a Class A code, meaning you need a scanner to reset it.