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HOW TO: Vent your crank case. Attn: FI members!

37K views 33 replies 8 participants last post by  3point5 
#1 · (Edited)
This thread is primarily directed toward people with FI, and even more specifically for those with built motors and set ups with Garret turbos (APS, JWT, etc...)
I have been running my built APS set up for a couple years now with pretty much no problems, but I've been noticing some oil smoke lately at WOT. I did tons of research into what could be causing this, and decided high crank case pressure was probably the likely culprit. Apparently, the Garret turbos are very sensitive to oil pressure, crank case pressure, etc, so I set out the fix the problem.
My oil catch tank set up the "normal" way was catching a good bit of oil, but I had nothing set up to allow the crank case to vent. The stock PCV is a known problem with higher boost, so I figured that should probably go. After a ton of research and annoying PMs to people smarter than I, this is what I've come up with. It allows the crankcase to vent without restriction, and also maintains vacuum pressure at idle. This allows the rings to seat properly at idle, and also keeps a steady supply of fresh air moving through the crank case.

What you need:
-Catch tank
-About 6 feet of reinforced 3/8 vacuum hose (I ordered 8ft and had a little left over)
-Brake booster check valve with 3/8 barbed ends - this is the hardest part to find. I ordered a check valve off a Nissan Pathfinder from autopartswharehouse, but I believe all the Nissan check valves are pretty much the same. Finding one with 3/8 barbs is the trick, I could not find one locally.
-3/8 Tee
-Mini-breather to fit on PCV
-2 connections to join 5/8 hose with 3/8 hose (I couldn't find these at the auto parts store, so I went to home depot and made some)

How to do it:

1. Remove front strut bar and plastic engine cover
2. Remove hose connecting PCV valve and lower plenum (in stock configuration)
3. Remove PCV


4. Drill it out. Remove the spring and little floating plastic piece




5. Replace now-drilled-out PCV into the valve cover and attach the breather to it


Now to the more complicated driver side.

6. Remove the charge pipe

7. LOCATE: There is a 5/8 heater hose that runs from the very back of the driver side valve cover straight to the driver side turbo intake (traced in red)


8. Find a nice place to cut it. I left about 6" of the original 5/8 hose running off the turbo intake because it was pre-bent, and made it very convenient to attach the new 3/8 vacuum hose.
9. Place your 5/8-3/8 connectors into both ends of the 5/8 hose you just cut.


10. Attach the 3/8 vacuum hose to the converter on the short hose coming off of the turbo intake. Run this new hose over to the lower plenum. Cut it your desired length and hose clamp it to the lower plenum inlet.


11. Attach 3/8 vacuum hose to the converter on the 5/8 hose running to driver side valve cover. Route this new vacuum hose straight to the catch tank and trim to desired length. At this point, all your new hoses are in place (we just have to add in a few goodies), so make sure they are trimmed just how you want them.
12. Replace charge pipe. Situate all new hoses how it suites your engine bay best.
13. Pick a spot on the vacuum line that is now running from the lower plenum to the driver turbo intake and cut it near the catch tank. Insert the Tee at this cut.


14. Run another 3/8 vacuum line from the Tee into the catch tank.

15. Pick a spot on the vacuum line running from the lower plenum (before the Tee) and cut it. Insert the check valve (this needs to be placed so that air can be drawn INTO the plenum, but NOT pushed back OUT into the catch tank).


16. At this point, everything is functional. I hose clamped everything down, which was probably completely unnecessary, but just in case!


17. Bolt everything back up and go test out your new set up!


...for those of you who are still confused (if that's possible), I drew up a little sketch for you...



Hope this has simplified everything, I would encourage anyone running high boost to check out some type of crank case ventilation set up like this...
Good luck!!!
-Willy P-
 
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#3 ·
I gave it some good pulls tonight, the car reacted great!
...I am idling leaner though, what is "too lean" for idling?
 
#5 ·
Oh, well it is idling at about 16, so that's good news : ) It stumbles like once every 60 seconds I'd say... Having said that I don't just sit at idle for long periods of time, I only notice it at long red lights...
 
#7 ·
Well I was suspecting that it is because the PCV is now breathing and the plenum is routed a little different, but I'm gonna go look for leaks just in case :)
 
#9 ·
Haha, that is correct... you're a smart guy even before you're awake : )
 
#10 ·
Ok, so I noticed my a/f was lean and my boost gauge was reading less vacuum pressure. It didn't occur to me at first, but this obviously means there is more air flowing into the plenum vacuum spot with less resistance. Obviously this is because with my set up, air was flowing into the plenum through a reinforced 3.8 hose at the SMALLEST, where as in the stock set up, it is sucking air through the PCV which is restrictive and only a 1/4" hole. It kind of hit me, then, that I needed to add some resistance back into my hose that runs to the plenum.
So, I went and got some 1/4" hose and rigged some more adapters.


Even this was not nearly as restrictive as the PCV so I made a little loop of 1/4 hose (the longer the hose, the more restriction there is...)



This about did the trick. It is SLIGHTLY leaner than it was, but I think it WAS too rich. Now, my a/f is back down, my vacuum pressure is back up, and my idle seems to be pretty much perfect again...



Just tucked it away back underneath the engine cover, and everything seems to be running great!!!

...hope this helps someone....

-Willy-
 
#11 · (Edited)
Hi Willy been following your catch can development ( with Kam ) and my research has come up with the same system as you have but with another check valve between the "T" and the intake. My reasoning was for the plenum to draw using vacuum at idle and low rpm and the intake to draw at higher rpm. So to avoid unmetered air and to safe guard against backfire i came up with the 2 check valves. This may explain your lower vacuum. I like your 5/8-3/8 reduction method. I'm going with a HKS S/C. Do you recall the part number for the check valve?
 
#12 ·
Where would you put the other check valve? (note the arrow on my diagram is actually drawn backwards)
...putting a check valve between the can and the turbo in take would allow air to but sucked only into the intake and not pushed back out. This should be superfluous, though, because the turbo intake is always under vacuum and never making positive pressure that would push back into the can, and thus need to be blocked. The plenum DOES make positive pressure under boost, so it must have a check valve...
note, there is no check valve in the stock set up for this reason...
 
#13 ·
Thats what we need, the intake/plenum doing the work of evacuating the crankcase of all the blow by gases at all of the rpm range. The plenum (vacuum) at low rpm and the intake at higher rpm ( as more air rushes by the opening it draws the gases through CC. So we don't want air being forced back int the CC at any time , hence my reasoning for the check valve between the CC and the intake.)
I'm hoping the CC will be efficient at this point and doing it's job not letting any oily contaminates into our intakes and IC.
 
#14 ·
That is exactly what is happening with my set up... I have 2 more check valves sitting in my floor, but there should be no reason to put another one in... the turbo intake doesn't "boost" so to speak, it cannot force pressure back into the crankcase like the plenum can, so there's not need for a check valve on it...
I know it's confusing, I will try to draw separate diagrams for airflow under idle (plenum vacuum) and airflow under boost (turbo intake vacuum)
 
#16 ·
#19 ·
Here are some more complete diagrams I drew up... I hope this clears up any confusion with the check valve(s)...



 
#20 ·
Hey Willy great diagrams they are great way to visualise , i did the same. What i'l do is the same and monitor the intake hose. I'm going with a HKS S/C.
How is your CC setup running has it collected anything? Your motor is built so i imagine its running without any or much blow by.
Was the valve the right diameter for the 3/8 hose you used? Just as a side note Nissan Australia quoted me $66.00 for the check valve! Thats gouging!!!
 
#21 ·
I don't know how shipping to australia is, but I doubt it is $66... I have 2 sitting in my floor, lol...

Catch can it catching a bit...I'm running 16 psi, so some oil does get by at high boost... it doesn't fill up overnight or anything, but over the course of a month it filled maybe 100mL I would guess.... smells like fuel and looks like oil, gross.
 
#24 ·
:) !

glad I could help... I'm in Jacksonville, just stop by when you're passing through sometime :) ...or maybe we can knock it out at a tech day...
 
#26 · (Edited)
...yaaa looks like there's some oil spray going on in there...

Okay, wait... is that piece you're holding in your first picture always disconnected??
Where are those hoses in your last picture coming from??
 
#28 ·
Yes. The shop vented the entire set-up to atmosphere when the thick smoke would not stop coming out of the exhaust (this only happens when they hook-up the hoses to the catch can). So now this unattached hose sprays oil under boost. It drips oil if I'm regular driving.


The third pic is a view of the driver's side. There is a 'T' connector that is vented to atmosphere (just on top of the filter).

In the 4th pic I'm holding the second hose that's vented to atmosphere.
The 5th pic shows the 'T' connector that should be hooked up to that hose I was holding in 4th pic.

6th pic is just next to that 'T' connector, I'm showing you the "OUT' side of the catch can going to the exhaust side (has white tape on it goes to turbo).



So, since the ventilation has solved your exhaust smoke, the first thing I would try is putting a little plastic connector on the end of that hose and slapping a mini filter on the end... should take about 1 minute and no tools...
Try to point the mini filter up.... Or point it down where you don't mind oil dripping out. At least it won't spray everywhere :)

...I'm still trying to figure out all those connections you have going on though...
Don't know which hose to hook up to mini filter. I just need to make a road trip to G-Ville.... :)
 
#27 · (Edited)
So, since the ventilation has solved your exhaust smoke, the first thing I would try is putting a little plastic connector on the end of that hose and slapping a mini filter on the end... should take about 1 minute and no tools...
Try to point the mini filter up.... Or point it down where you don't mind oil dripping out. At least it won't spray everywhere :)

...I'm still trying to figure out all those connections you have going on though...
 
#31 ·
Ok, I actually revisited this a bit today. I used clear tubes the first time around so I could visually see where oil was going. The driver side is working like a charm. The tube coming out of the crank case is stained with oil, while the one going into the intake is not. Check. But, the one going into the passenger side intake was a little oil stained. Also, the catch tank was not catching as much as it probably should. So, the first time around I did not put anything in the tank, but I have read that it isn't very useful without something stuffed in there. I did a little research and found the best thing to put in there is probably some stainless steel pot scrubber little steel balls. I picked up 4 from the grocery store, and spent my day stuffing them in the catch tank. They are bulky enough that they have far greater integrity than stainless steel (which is what I bought at first, but decided against putting in) but still plenty porous to catch a bunch of oil.
I also put a new clear tube on so I can tell if oil is still getting in.
I'll update again soon and let everyone know how it's going!
 
#33 ·
reviving this :)

Does anyone see problem with just capping of the plenum port, running a breather on passenger side valve cover and then route the drivers side valve cover through the catch can into the intake (pre turbo and maf)? Same setup as Willy has but just capping off the plenum port essentially.
 
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