Help- Oil leaking through AOS
 

Hi guys, I think it’s about time I take to the forums to see if anyone has any advice or experience to help me solve a problem I’m having with my FRS.

Ever since I installed the turbocharger onto my car (JDL Kit, G25-550 Turbo, 10lbs) I’ve had a lot of oil leak through my Verus Air Oil Separator (AOS) when I drive the car hard. Basically oil leaks from both the PCV and front crank port (as far as I can tell), so much oil that it overflows the AOS and leaks out of the exit hoses of the AOS. For those of you who are unfamiliar with the Verus AOS, it has two intake ports that connect to the PCV (it deletes the PCV valve and replaces it with an open port) and the front crank case port and has two exit ports which I’ve routed underneath the car so the air flow underneath the car acts as a vacuum to create suction for the AOS.

I have two other friends who are experiencing the same issue. One has the same turbo kit, turbo, and AOS as me and his car smokes and leaks oil through the AOS during highway pulls. The other has a GReddy T518Z turbo kit and Radium catch cans. His cans overflow and leak oil. The friend with the GReddy has also noticed some oil leaking through the timing cover, possibly due to increased pressure. The weirdest part of my friend with the GReddy turbo kit is that he was supercharged at first, switched to turbo and then started having this issue which means it might have to do with the turbo more than boost itself.

At first I feared my piston rings were bad or my ringlands had cracked. However, my compression test came back good. I considered that maybe the PCV delete or running the stock PCV caused the issue, but my friend with the GReddy kit had the STI PCV valve and still had this issue. Another theory is that when we installed our oil pans, we applied too much RTV and some may have clogged the oil pick up causing increased pressure in the system. However I find it hard to believe that all three of us put too much RTV and all clogged the oil pick up.

Does anyone have any ideas or experience with this issue? Thanks

Get the drain back kit that verus sells.

I already have it. It's not that simple. The AOS is leaking a lot of oil. The AOS is meant to only see a small amount of oil, mainly in the form of vapor. Not consistent fluid.

Could be a few things

The breather hoses are restrictive, are the hoses still OEM size? Are you feeding IN 2 hoses with only 1 OUTLET?

VTA or recirculating?

You may be having issues with your PCV, which PCV are you using?

Any restrictions in the venting system will pressurize you engine, this will blow oil up and out.

An issue with a PCV will have simular results under boost.

https://axleaddict.com/auto-repair/H...PCV-valve-test

Mine uses a WRX PCV

The hoses are OEM size, however I use a Y pipe to connect both my outlet pipes together. I’m not sure if this would be the cause because I know someone with an identical set up and has no issues but I could try deleting the Y pipe.

VTA. At first it was recirculating but the AOS dumped oil into the intake. I assumed this was because 10lbs of boost created too much vacuum and pulled oil through the AOS, however the problem persisted even when vented to atmosphere. My friend with the GReddy kit has that Radium catch cans which are recirculating.

I am not running any PCV. The Verus AOS deletes the PCV entirely and replaces it with a port. However my friend with the GReddy kit has the STI PCV and still has this issue.

How low on the sump is the oil return line.

I had a sump made for a RB a while ago, the issue was the return was at the oil level in the sump.

A little bit of crankcase pressure would push oil up the hose and overflow the can.

I ended up fitting a one way valve on the line, this fixed the issue.

It was easier to fit a oneway valve than pull the engine and redo the sump.

-10an if I can recall correctly

Like this >

Post up pics of your whole breather set up.

I'm only running 8 psi, but I have no cans or AOS and I really use no oil.

Some of the AOS I've seen seem to be for NA, other, like yours, use a Y peice reducing flow by 50%.

If yours is VTA, it shouldn't be seeing any boost pressurizing the engine/sump, it could only be blow by pressure, which shouldn't push enough oil vapour out to over come the AOS with a return line, but as it is returned, maybe its coming up the drain back.

Do you have sump baffles?

Does it only do it cornering?

What happens if you block the return?

I am with 86MLR. Post pictures/diagram. the separator you have is small but you should not be getting that much blow by.

The AOS return line uses a check valve almost identical to the one you included in your picture. I double checked that the valve was faced the correct direction and it was the correct direction. However it is not a bad idea to try the AOS with no return line attached and also to have two VTA tubes instead of one. As I mentioned, I know two other people having the exact same issues as me. The one who has the same AOS has a Y pipe and the return line as well so it’s possible that maybe that could have something to do with it. I do not have sump baffles and it generally happens under full throttle acceleration in the straights.

I have attached a picture which shows how my AOS is set up. It is not my picture but it is the same AOS as me and same exact hose routing. Just a note, the person who took this picture is not having the same issue as me. I guess I am just unlucky... lol.

So you have set up your breather system without PCV? Not much else to do but live with it.

The Verus AOS deletes the PCV because it essentially acts as a PCV on its own. But no, this is not normal behavior and not something to “live with” because, like I said, my friend is running the STI PCV and is having the same issue. So the PCV, or lack there of, is not causing the issue from what I can tell.

Update for anyone interested- I made a couple changed. First I replaced the Verus Oil Return Line with a braided Nylon line that doesn't bend like the one they provide. Second, I added a WRX PCV valve and used the stock hose to route it to the AOS. Third, I separated the two VTA hoses and kept them as two hoses. Before, I used a Y Pipe to turn the two hoses into one VTA hose. I took the car to the track with this set up. There was still a small amount of leakage but not nearly as much as before. I attribute this mainly to the reinstallation of a PCV valve. The problem definitely isn't solved, but at least this is a start and I can track like this. I may try a different AOS to see if that provides a long term solution.

Another update for anyone interested. I decided to buy a different blow by solution to see if this changed the issue. I purchased the Full Blown catch can and once again deleted the PCV so it was set up exactly how they recommend. During a track session my car leaked over 1 quart, possibly 2 quarts of oil and my motor threw a rod.

The moral of the story is if you have a boosted 86/FRS/BRZ and you notice excessive blowby when driving hard, keep the PCV installed even if your catch can or AOS recommends otherwise. I can’t explain why but some boosted FA20s have huge blow by issues when boosted.

Sorry about tbe rod. I thought adding a crank case vacuum pump wojld solve the problem. It usually seals everything up nicely and seals rings tighter to cylinder walls