E30 Turbo/PCV help - I'm a boost newb

Hey all,

I got my turbocharged '86 E30 eta running again yesterday for the first time since I took it down to redo all the intake/charge/exhaust plumbing in November. Turns out I have a massive oil leak. One of those where it's hard to tell where it's all coming from. It appears to be leaking out from the valve cover gaskets and also somewhere down below the turbo, maybe near the drain back.

Being somewhat new to E30's and definitely new to boost, I'm fairly certain it's from pressurizing the crank case. I think the stock setup is with a breather hose from the intake manifold to the valve cover with no check valve, which would be the obvious culprit for pressurizing the crank case (and also why these run like crap with the oil cap off - big vacumn leak).

So now I'm down the rabbit hole trying to figure out exactly what sort of system it needs, without following the wrong info that seems to abound everywhere on this subject. Here's what I've gathered so far, please let me know if this plan makes sense and If I'm missing anything or there's an easier way to do this.

-First, can't just stick a PCV inline on the stock breather as I hear they don't last long under boost. I'm only running wastegate 6ish psi to start but don't see myself going past 10 psi as I want to keep this somewhat reliable, if that matters.

-Now I have the option of running the breather to atmosphere or to the intake plumbing pre-turbo. I'll need a catch can either way, because messy, or because I read that oil in the intake charge = bad for turbo longevity.

-This leaves the question: Do I need to plumb for the vacumn pre-turbo or can I get away with just atmosphere? If just atmosphere, do I need a pcv on the vent end of the catch can or just a filter?

thanks!

If you use a vent-to-atmosphere setup you just need a filter on the vent end of the catch can. This will cause your oil to get dirty quickly though and is bad for the environment.

A catch can going to the pre-turbo intake is slightly better for your engine and a lot better for the environment.

The best way to do it is The Hard Way with a bunch of check valves and maybe even a vacuum reservoir.

Ok, so pre-turbo is minimum. I'm not opposed to the Best Way, but would love some help figuring that out.

Chrysler and other turbo cars in the 80's had PCV check valves in their systems. Worked just fine and yes they were wear items, but honestly the engine shouldn't be blowing oil around and once you stop that from happening, the PCV valves last much longer.

The Chrysler system uses a hose from the intake after the TB into the top of the check valve. So that under boost, that valve would close to keep the boost out of the crankcase. The bottom of the PCV valve went into the left side of a "T" and the bottom of the "T" went into the valve cover. The right side of the "T" went into the air box to allow the fumes to recirculate (this could go into a catch can for a track car).

This solution worked without issue to well over 14PSI for decades.

Some of the racers who run upwards of 30psi would add another breather to the valve cover. While others would run the vent tube to the exhaust with a fitting installed at 10 degrees to use the exhaust to pull a vacuum on the crankcase and improve ring sealing.

I'd just run a vented catch can.

Ok, wear items are cool, fail items are not.

I was about to ask why bother with the line from the intake, but I get it now. If the intake manifold isn't pulling vac, the turbo intake must be. So is another check valve in the line from the intake necessary to keep unmetered air from being pulled via that route?

Ok, I give up. What the heck is this thing? Pulled it from a turbo Volvo at the yard along w/ some other check valves anticipating the need. Now I'm trying to figure out its function but googling the text/numbers on it just returns VAG parts. Tried blowing/sucking air through it different ways but I can't figure it out (twss?). "Volvo" "639291S(5?)" "Germany kys pa6 gf30"

Link to pics since hotlinking to my DB never seems to work:

https://db.tt/yo5qgIwY

https://db.tt/48eoqwvB

https://db.tt/aAP6BxpZ

Venturi tube with a check valve. 944 turbos used to have them, deleted them via TSB quite a while ago.

Ahhhh! Thanks again! Here's a link to one cut in half as well: https://www.bimmerfest.com/forums/showpost.php?p=6429395&postcount=29