Ok guy's I have done many searches but I’m stilled puzzled on how to run and why to block the pcv. And yes I feel like an Idiot for asking such a dumb question but it's bothering me. So I’m hoping to come out of the med/rare and not well done. lol

This was the topic i got the most helpful info from.

The reason i'm cunfused is because my freind on his KA-T has alot of oil in his catch tank and i do want to run the lines the wrong way.

Why would you remove the pcv valve is it because I am going to run a catch tank?

Ok this is how I interpreted on how it should be ran.

well what rb do you have if its an rb26 then you want to run the hose from the valve cover out let on the exhaust side to the catch can and then from there to the intake and leave the pcv alone. on the 25 and 20 im not sure but similar

this is the link i was reading ( forgot to post it)zerothread?id=282518

yhea its a rb25

this is how i was thinking of running it but not sure if its right.

i see a flaw in the setup in that picture, unless there's something hidden i can't see. the reason so is, that square catch can must be vented, to relieve the crankcase pressure, otherwise i will guaranty you all that will push out to your turbo seal will result in dipstick popping out and blown turbo.

wow this has been covered so many times I even drew a few diagrams BUT

its simple the goal is to vent the air from the crankcase so you hook it to a vacuum source AKA the intake pipe after you air filter but before you turbo that way it see vacuum but no pressure. But if you did just that you would collect oil in your intake track so you need a catch can to CATCH the oil, SO on your catch can you have two upper fittings, hook one to the valve covers, and the other to the intake pipe as described above. the lower fitting on the can is a drain, if you hooked it up the way you described you would catch the oil only to suck it into the intake via the hose hooked to the drain lol. And the picture you have of the Blue motor shows how not to hook up a catch can

I personally flipped the fitting on my exhaust side valve cover so I could keep the two valve covers connected and then ran the unused fitting on the cover to run to the catch can.

search the forums / archive i also pictures and diagrams as examples.

please post the links ...i did the search and it came out 3 posts only

Searched for "breather tank" in the archieved thread bodies and found quite a few.

zerothread?id=256193http://forums.nicoc ... ?id=131984

thank you for the post

i looked at the other links posted and someone mentioned allowing the caught oil in the bottom of the catch can to drain back to the oil pan, is there anything bad about putting a "T" in the oil drain tube for the turbo to accommodate this idea?

I wouldn't do it for street use. A lot of moisture collects in that can and you don't want to keep returning it to the crankcase to be used in lubricating the bearings/rings/cams etc.

ah i see, makes sense, thanks for informing

i don't really see an issue with a drainback if its a sealed system. if you are venting to atmosphere then its probably a bad idea due to moisture

The OP reminds me of Direct Exhaust Injection lol

gawdzilla wrote:i don't really see an issue with a drainback if its a sealed system. if you are venting to atmosphere then its probably a bad idea due to moisture

It depends on your air filter if it lets too much moisture in then it goes right to the can and condenses.

But the important fact is if you are catching enough oil in the can that you need to drain it back to the pan then you have other problems like rings lol

I made a filter for my catch can, which is the picture posted. I check my engine over and the catch can on a weekly basis, and so far its bone dry. Although, i do change my filter regulary. Which consists of a block of soft foam with gauze around the bottom and IT does pull a good amount of vacuum through, and enough to cause a maf leak if you unplug on of the hoses. It needs to be a sealed system and secure because it can lead unmetered air. Just dont ever vent a catch can, i cant see any logical purpose of a catch can system thats vented with no vacuum drawn through it, but not enough to cause lubrication problems and suck the head dry because i actually have very little oil come out of mine now that i've taken care of a few other things.

I also removed the PCV valve and blocked that nipple on the intake manifold. The one way check valve on the PCV actually broke and was letting small amounts of boost into my head and crank case causing more than usual amounts of oil out the top of the hose.

Im about to ditch that style of catch can because its a leaky piece of shi-t. Its MAF leak central after an extended period of use.

You just need to be smart about using it and you'll be fine.

heres my question.. i know it may not be the right forum but its the right thread..

i have a KA-T, i was going to run my catch can like this

breather on the valve cover-catch can-back into the intake tube before the throttle body

because right now my breather is directly connected via a tube to the intake tube before the TB. however after searching i see some people using the PCV... was my original plan correct?

KA-T dude.. With your idea, think what happens under boost... Your pipe right before the TB (where you are hooking your tank into) is going to be pressurized... So your tank is pressurized, and now you've pressurized your valve cover(s) which is exactly what you're trying to avoid. You would need to use a PCV/check valve somewhere, and even then how are you going to vent your valve cover(s) when under boost? Easiest solution is to find a constant vac source (aka turbo inlet pipe somewhere after the maf) then plumb it to your catch tank, then have your tank plumbed to your valve cover(s).

There are a few different ways to plumb it though, check the threads linked above or hit up google for some more "exotic" ideas.
Modified by mello88 at 3:02 PM 1/23/2008

mello88 wrote:KA-T dude.. With your idea, think what happens under boost... Your pipe right before the TB (where you are hooking your tank into) is going to be pressurized... So your tank is pressurized, and now you've pressurized your valve cover(s) which is exactly what you're trying to avoid. You would need to use a PCV/check valve somewhere, and even then how are you going to vent your valve cover(s) when under boost? Easiest solution is to find a constant vac source (aka turbo inlet pipe somewhere after the maf) then plumb it to your catch tank, then have your tank plumbed to your valve cover(s).

There are a few different ways to plumb it though, check the threads linked above or hit up google for some more "exotic" ideas.

Modified by mello88 at 3:02 PM 1/23/2008

hmmm, so instead of the cold pipe by the throttle body, should i plumb it back into the turbo inlet where my maf and air filter is??

it seemed so simple

you possibly just saved me an engine <3

my setup with ebay can

Instead of using the stock small-a$$ nipples, I bought a 3/8" NPT 2" long nipple, cut it in half, and threaded them into each of the holes. Now it has a true 0.5" holes going to the valve covers.
Modified by sepulchralx at 6:17 AM 2/16/2009

hey i got an rb25, and i want to change my hoses to the clear ones like that. do you know what hose diameter to by to fit where the stock ones are? i think its 3/8's but im not sure

ok...i havent read all of the posts but they all seem to be the same....basicly vent both rocker covers to the catch tank....dont reconect the catch tank to the intake pipe...put a breather pod on the catch tank so the crank case vents to atmo...look at this ...



or this

300Plus wrote:wow this has been covered so many times I even drew a few diagrams BUT

its simple the goal is to vent the air from the crankcase so you hook it to a vacuum source AKA the intake pipe after you air filter but before you turbo that way it see vacuum but no pressure. But if you did just that you would collect oil in your intake track so you need a catch can to CATCH the oil, SO on your catch can you have two upper fittings, hook one to the valve covers, and the other to the intake pipe as described above. the lower fitting on the can is a drain, if you hooked it up the way you described you would catch the oil only to suck it into the intake via the hose hooked to the drain lol. And the picture you have of the Blue motor shows how not to hook up a catch can

I personally flipped the fitting on my exhaust side valve cover so I could keep the two valve covers connected and then ran the unused fitting on the cover to run to the catch can.

quoted for the sake of quoting

the two tops are suppose to be separate becuz the bottom one was suppose to be the draining end. the two top inlets one is for the intake manifold and the other mmm it seems I forgot damn brain farts well yea I'm guessing u'll find our wat the other one is for

300Plus wrote:wow this has been covered so many times I even drew a few diagrams BUT

its simple the goal is to vent the air from the crankcase so you hook it to a vacuum source AKA the intake pipe after you air filter but before you turbo that way it see vacuum but no pressure. But if you did just that you would collect oil in your intake track so you need a catch can to CATCH the oil, SO on your catch can you have two upper fittings, hook one to the valve covers, and the other to the intake pipe as described above. the lower fitting on the can is a drain, if you hooked it up the way you described you would catch the oil only to suck it into the intake via the hose hooked to the drain lol. And the picture you have of the Blue motor shows how not to hook up a catch can

I personally flipped the fitting on my exhaust side valve cover so I could keep the two valve covers connected and then ran the unused fitting on the cover to run to the catch can.

this is exactly how i was about to hook mine up. leave the factory pcv valve in place and run the valve covers tee'd to the catch can inlet and the the other line on the catch can to the factory inlet on the intake piping before the turbo. it'll work just liek the factory system that way. pulling vapors through the pcv when under vac and through the can the rest of the time

only thing i've been debating about doing different is ditching the pcv valve for a filter and blocking the intake manifold inlet for the pvc valve line