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Trying to understand why changing my PCV setup may have caused my BNR Stage 3s to start leaking oil.
The issue:
There is oil leaking out of the body of the turbo itself, right behind the front (toward front of car) oil return line. It smokes once the turbos gets hot.
for reference, i did contact BNR and they suggested more PCV ventilation and hooking up the primary turbo vacuum to the setup would solve it. I definitely believe them but just trying to understand mechanically why this might be happening.
My previous setup was a closed loop catch can setup with: vac line off the oil filler, to a closed catch can that was baffled and had another line running to the primary turbo inlet. With this BNRs did not smoke but I also didn't catch much oil for some reason and during sustained right hand turns I had oil all over the driver side of the engine.
To combat this i installed a baffled filler neck (half moon baffle) that had provisions for a 10 AN port which is hooked up to breather can, no vacuum pulled on this. With this setup is when i noticed the oil leaks from the BNRs.
I'm waiting on some barb fittings to experiment to see exactly what happens with vacuum and I'll follow up in this thread with results but curious if anybody might have insights into why this might be happening, Appreciate yalls knowledge!
As I understand it there’s no way an adequately ventilated crankcase should push oil like that, even if not hooked up to vac. However, from reading around on here it does sound like its critical that the vent be big enough. -10 like you have seems to be best practice, but if for instance the opening to the filter or the filter itself are too small they can also be a restriction. Could that be your issue? Some of the Amazon catch cans I’ve seen may have -10 fittings for the lines but the vent filter attachment is really narrow.
You're on the right track. This 3rd revision is going to be the one. Always a vented can over non. The goal is to give the crankcase breathing room so the more vents the better. Running the vented can with the port going to the intake is really the best you can do with the twins. Oil neck--> vented can---> intake.
Keep in mind the intake is not a vacuum. Its providing some suction sure but its not a vacuum. Your vacuum is behind the throttle plate. If you wanted, you can run a line from the stock pcv location with a check valve to the can as well. A proper spaghetti monster.
The BNR stage 3s use low drag dynamic compressor seals that help spool over stock carbon style.
Sounds like the dynamic seals are leaking and seeping out between the compressor and center section.
Dynamic seals depend on pressure differential.
You have too much oil pressure going into the turbo and or too much positive pressure in the oil drain/engne sump. Its a balance.
Since I assume you havent increased oil pressure since the problem started, lets look at the rurbo oil drain pressure.
Check to see if engine oil level is too high (above turbo oil drain is a big issue).
Is oil getting up into the -10an line to catch can and making a vapor trap like a toilet or can the line completely drainback into either the catchcan or oil fill neck (no low spot)?
If there is liquid oil blocking the -10an line or blocking the halfmoon cut-out baffle you made on the oil fill neck the engine sump will build up pressure.
Car background
The oil pressure SHOULD be stock, sat around 40-50 PSI idling I didn't modify the regulator during my rebuild and no internal modifications to the block. Other oiling mods that i dont think should affect pressure are dual mishimoto 25 rows and a FFE pedastle.
The catch can is the Vibrant two port universal, with two inlet 10 AN ports (one is currently capped) and the breather filter element is relatively large. The can itself is pretty big, maybe 1.5 liters maybe?
Current oil levels are actually a bit low, it's at around quarter dipstick.
The issue is occurring at idle as well. There should be no obstructions for the actual catch can line or the baffle but I might stick a brush or something in the filler to see if maybe I do have a plumbing style P trap with oil blocking ventilation.
For reference, the issue was occuring with no catch can, just an open 10 an port on the filler neck.
@BLUE TII
Could the dynamic seals be permanently damaged from a high pressure event or pressure differential?
i ran 20w-50 for a bit and maybe that caused excessively high oil pressure? Or maybe I over filled at some point and ran more oil in the pan than I should have?
additional steps
For troubleshooting, I was going to hook the capped 10 an port inlet to the primary turbo inlet but since the can is a vented system, the vacuum would just pull from the vent in the can before diverting any positive pressure from the crankcase (at least I think).
so to see for sure if vacuum is the savior, i was going to hook up vacuum from the primary turbo inlet to the opening on the filler neck, no catch can at all.
alternative setups I can run is the IRP filler neck, which has a 10 AN AND a 1/8 NPT. I can retain my 10 AN setup for the catch can but unless I'm over thinking, wouldn't the vacuum pulled via a barb fitting on thr 1/8 NPT port still pull from the vented catch can?
maybe I can drill a hole below the baffle on the filler neck and put the vacuum barb fitting there? But even then am I really pulling vacuum from the crankcase effectively enough with the open catch can still attached?
I don't know, I'm just not sure what the best route to alleviate the Positive pressure would be without getting a whole new closed system catch can setup that can actually technically DRAW vacuum...
Dynamic seal should recover from improper operating dynamics from what I know since there arent wear components like in the stock carbon disk seals.
So... story time?
On my BNR stage 4 (single turbo using modified stock S5 TII exhaust housing/manifold) I had a slight oil leak from the other end of the turbo (shaft ring seal) into the exhaust.
Symptom was it would smoke at idle if I revved the engine (oil pressure spiking to 120psi) and then let the idle settle back to idle.
I "fixed" this by putting in the recommended turbo oil supply restrictor and putting engine sump under vacuum so the turbo could drain fast enough. I did a baffled catch can with inlet from oil fill neck at the bottom and vacuum hose from behind throttle body at the top.
I didnt like how hard cornering would fill the catch can and the vacuum would suck the oil into the intake when racing.
In the end since I had done all the other oil mods, I put in the Mazda Comp e-shaft rotor oil squirters.
These flow oil at idle since they dont have a ball check valve like stock and they limit oil flow at higher rpm because they have smaller jet size than stock. This allows more oil to flow past the rotor oil jets inside the e-shaft and get to the rotor bearings.
The Mazda Comp rotor oil jets dropped my oil pressure at idle low enough I was able to run an open vented catch can so I didnt suck oil into the engine.
Raced and drove this setup/turbo for another decade- no issues.
Welp, did a fully closed loop setup and unfortunately, still getting smoking from the primary turbo ☹️.
I'm attempting to draw vacuum from the primary turbo inlet but perhaps this isn't enough vacuum? I'm waiting on a T fitting to draw vacuum from the UIM as well but I'm worried that even if this prevents oil leakage at idle, during boost, the check valve will cut vacuum from the manifold and I'll suffer from oil leakages (unless the turbine spinning up during boost creates enough vacuum to offset this).
Here's my setup currently for testing. The 6mm hose is hooked up to the hard-line that goes down to the primary turbo inlet. The AN line that goes to the catch can is definitely convoluted but with the KS v mount and stock intake elbow, it's hard to fit anything else
I "fixed" this by putting in the recommended turbo oil supply restrictor and putting engine sump under vacuum so the turbo could drain fast enough. I did a baffled catch can with inlet from oil fill neck at the bottom and vacuum hose from behind throttle body at the top.
so I hooked up the BIG vacuum nipple on the front of the FD UIM directly to the catch can and its wrecking havoc with the idle. And more annoyingly, there is an UNGODLY wailing sound coming from the UIM...
Iirc, this actually is where the stock PCV valve is setup. Good thing is, I THINK the large amount of vacuum pulled is preventing the oil leak but im not sure what the wailing is all about...
The PowerFC started to go into an idle learning process, where it was hunting for idle but with the essentially open PCV, i think the idle was too high for it to adjust (1800 RPM).
I imagined that the stock PCV was a 1 way check valve, letting vacuum in from the filler neck in a stock setup and preventing boost from entering the crank case but does it do something else I might be missing?
Is the wailing sound the vacuum collapsing the walls of soft silicone hose?
I used smaller hose/smaller nipple- but do kind of recall a squalling sound from the silicone hose or a check valve and the vacuum now that you mention it. I forget what I did to stop that.
Was it to put a big loop in the hose instead of letting it kink at a bend?
I don't think PCV valves are simply a check valve, although I haven't tested one to confirm. I suspect they have a specific crack pressure or a carefully sized restriction in them somewhere, to avoid pulling strong vacuum in the crankcase. If it were me, I might try a stock PCV valve inline with your catch can lines.
why not do the smart, direct, and effective solution by reworking the oil supply line with either an adjustable pressure regulator or adjustable pressure snubber device?
Crankcase venting is an entirely separate issue. If you want to solve a problem then cut straight to the chase.
Further; the last thing you want on a performance engine is to suck crankcase fumes into the intake. That’s only for emissions purposes. If you want to hug trees and make sweet love to the musky earth then stop being a hypocrite and drop your rotary-engine powered vehicle off at the auto crusher and go ride a bicycle instead.
Or just spend time playing silly forum word games debating half-rectumized hillbilly garage solutions. I’m only 1 generation from my hillbilly heritage though, so don’t hate on me too much for stating it that way.
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why not do the smart, direct, and effective solution by reworking the oil supply line with either an adjustable pressure regulator or adjustable pressure snubber device?
It sounds like BNR suggested crankcase vacuum might not be letting the turbos drain quickly enough. Here's a snippet of his first post.
Originally Posted by zli944
for reference, i did contact BNR and they suggested more PCV ventilation and hooking up the primary turbo vacuum to the setup would solve it. I definitely believe them but just trying to understand mechanically why this might be happening.
I agree the supply side of things might be the problem (not the drain as BNR suggested), but I'm not a turbo expert and this isn't a problem I've encountered or solved myself.
Typically combative, I think the internet forum environment really is tailor made for ya TeamRX8
You're not wrong but you're also not right. The process to create an effective closed loop catch can would be great for the car in general but given the turbo leaks, could alleviate that problem. It's also the first choice since it's literally what the turbo manufacturer suggested as the cause of the leaks.
But if vacuum and ventilation don't resolve the leaks, obviously solutions would need to be more drastic, such as regulators on the inlet (NOT looking forward to that replumbing project).
A restriction in the turbo oil feed line (and resultant pressure drop post restriction) is the classic solution for lowering turbo oil feed pressure when moving from compressor carbon seals to dynamic seals and/or floating journal bearing to ball bearing.
Ask Bryan what his minimum recommended orifice size is or if they are already installed on your Stage IIIs.
Words of waning from my experiences-
If you make make a restrictor plate at the two bolt flange on turbo center housing, keep the factory gasket on the turbo.
I had used a copper plate restrictor and Hylomar and the heat from turbo transferred into BRAND NEW oil supply pipe and cracked the welds from expansion very quickly. Big fire and toasted engine at top of 4th gear.
Turns out the factory gasket is Asbestos to block heat transfer.
There's a Turbosmart T40 product that restricts the feed pressure to 40 PSI while not necessarily restricting flow. I'll reach out to Bryan to see if that pressure is appropriate for the Stage 3s.
*Bryan let me know the T40 would be fine for the twins*
I have a final test with the OEM filler neck (no half-moon baffle), which was the setup I had previously on the BNRs that did not leak but if that fails, I'll need to explore TeamRX8s suggested oil feed route.
Thinking ahead, if I need to go that route, the plumbing will be interesting.
:mental diarrhea incoming:
T40 Fitting sizes: -4AN
Front Iron feed fitting size: 14mm x 1.5 (female)
Front Iron feed to turbo line junction: 14mm x 1.5 (female)
Turbo feed fitting size: 14mm x 1.5 (male)
Easiest route would probably to modify the hardlines with -4AN fittings welded. The main consideration being that modifying the OEM turbo side feed line would be annoying, so I would want to keep the 14mm x 1.5 male side for my own sake. If there was a fitting that went 14mm x 1.5 female to -4AN, that would be ******* great but looks like they're all to -6AN, go figure.
After I cracked the stock turbo oilfeed line I made a hardline to -4an soft line of my own.
Since I was familiar with their excellent fittings from work I used Swagelok Stailess double ferrule fittings to adapt from aftermarket Aluminum 2 bolt turbo oil feed flnge to Stainless tube and stainless tube to -AN fitting.
I also used Swagelock fittings to adapt 8mm stock steel hardlines to -an.
Swagelok has lots of adapter fittings and I have never had a failure when correct material of Swagelok fitting is used (make sure ferrules are harder material than tube they are swaging).
Do not use the common tube adapter fittings that depend on deforming a single ferrule onto the tube- shady AF...
After I cracked the stock turbo oilfeed line I made a hardline to -4an soft line of my own.
Since I was familiar with their excellent fittings from work I used Swagelok Stailess double ferrule fittings to adapt from aftermarket Aluminum 2 bolt turbo oil feed flnge to Stainless tube and stainless tube to -AN fitting.
I also used Swagelock fittings to adapt 8mm stock steel hardlines to -an.
Swagelok has lots of adapter fittings and I have never had a failure when correct material of Swagelok fitting is used (make sure ferrules are harder material than tube they are swaging).
Do not use the common tube adapter fittings that depend on deforming a single ferrule onto the tube- shady AF...
Oh interesting, so you cut the OEM hardlines at some point and installed tube to AN adapters?
07-30-22, 12:06 AM
