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Got Boost?
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216 Posts
Discussion Starter #1
Hey guys, just one question. I have recently done some work to my engine and i happened to notice when i take the oil cap off the cam covers there is a small amount of pressure coming out of them. Is this normal? Every other car ive seen has vacuum at the oil cap when you take it off. Im just confused. I have just hooked up a catchcan and its setup basically stock minus the throttle body vacuum. Is this my problem? Any opinions are welcome, please help me! Thanks.
 

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Supranian
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2,007 Posts
Bad piston rings....
 

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Got Boost?
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216 Posts
Discussion Starter #5
Its not blowby because the rebuild has only about 2500 miles or so on it by now and everything was fresh. I have also done two compression tests and a leakdown test since the rebuild just to verify the condition of things. The most leakdown i have right now is about 10 percent. I am willing to bet it is to do with the catchcan. Its not a huge amount of pressure but it is definately there. Racefiend, the way the hoses are run are as follows. I have the NA Y-pipe on the cam covers going into one side of the catchcan and capped off the throttle body vacuum. Then the other hose goes from the catchcan to the acordian hose like stock. Im thinking that maybe i need to hook up the throttle body vacuum again to solve this problem but im not sure... suggestions?
 

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Just some guy
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1,681 Posts
well, thats how they should be hooked up.....if you take the oil cap off, and take the pcv hose off the accordian, then blow through the hose, is there any restriction?
 

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Professional White Man
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2,674 Posts
it sounds like the catch can is hooked up right. When you drive hard, do you get some milky goo in the catch can, and does it fill up somewhat quickly? How often do you empty it between oil changes?
 

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Got Boost?
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216 Posts
Discussion Starter #8
Racefiend, i will check that out tonight and let you know. I was also wondering if its just because the hose that connects the crankcase to the cam covers comes in right there underneath the oil cap? Could it just be this air coming in and making like a pocket under the oil cap?

hoser813, to be perfectly honest with you i havent driven the car yet with the catchcan install. Im a little worried about blowing a seal because i have no idea how much pressure is in there under boost or even just when revved up. I would like to solve this before i drive it.
 

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Got Boost?
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216 Posts
Discussion Starter #9
Would someone be so kind as to check this out with their own car. I have a billet aluminum oil cap but im sure it would be the same with the stock plastic one. If someone could just idle their car and let me know what they feel at the oil cap with it either loose or off that would be greatly appreciated. I have a little bit of pressure but like i said before nothing excessive????
 

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wastegate hose is pulled
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4,586 Posts
By blocking off the throttle body port, you have eliminated half the positive crankcase ventilation system. The result is going to be positive pressure in the crankcase. This is normal and the reason why Toyota put a PCV system on the car. If it is any consolation, it is still working under boost the way you have it hooked up.
 

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Got Boost?
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216 Posts
Discussion Starter #11
I have hooked up the throttle body vacuum port back up now. I still have the floating weightless oil cap problem but thats ok. Im convinced that its just from the incoming air from the crankcase tube right underneath the oil cap. My setup is now exactly as stock only with an inline catchcan. This should work fine... i cant see why not? And Racefiend just so you know, i checked out the acordian hose like you said with the oil cap off and there is no restrictions. I cant be the only one with this problem though? It must be normal... someone else should check out their car and tell me if im alone or not on this one. Thanks again for all the help guys.
 

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Just some guy
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1,681 Posts
If there is no restriction, you should be fine. I've never trieed removing my oil cap with the engine running, but maybe I'll give it a shot to see what happens. What you need to do though, is stop using that overpriced japanese catch can crap. Get yourself a nice american made pcv catch can system, like this one:



I just so happen to be a manufacturer of such catch can systems. For just $50 plus $.05 California Redemption Value, I can have one sent out to you tomorrow (I have very short lead times). You let me know if you're interested :)
 

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Supranian
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2,007 Posts
Great idea Christian as they say, "Necessity is the Mother of Invention". Does your product come in red? :bigthumb:
 

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Supranian
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2,007 Posts
jkturner said:
Finally,

Someone with a brain and one THIS list.
Huh....
 

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Just some guy
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1,681 Posts
Welp, I tried taking the cap off my mk3 with it idling. Didn't notice any pressure. In fact it had a SLIGHT bit of vacuum (held a cigarette up to it to see if it drew in any smoke). This is with a totally stock PCV system.

chriso said:
Great idea Christian as they say, "Necessity is the Mother of Invention". Does your product come in red? :bigthumb:
I don't have any red in stock, but I can get them from my supplier. They only come in quantities of 6 and 24, so if you can get 5 other people, I can get a group buy together :p


jkturner said:
Finally,

Someone with a brain and one THIS list.
:dunno:
 

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Got Boost?
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216 Posts
Discussion Starter #17
Thanks, i actually found that if i unhook the hose going to the accordian hose all together and use only the vacuum off the throttle body it seems to be ok now??
 

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Just some guy
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1,681 Posts
^^^NO NO NO NO. That is no good. If you cap the hose going to the accordian, you will pressurize your crankcase during boost. VERY bad. If you take it off, but don't cap it, that is still bad becuase you will suck in unmetered air through the TB port. Hook it back up!
 

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Got Boost?
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216 Posts
Discussion Starter #19 (Edited)
Ok, well on that note then the system is getting hooked back up like stock then without a catchcan... so basically correct me if im wrong but to hook it back up to stock i just run from the throttle body vacuum port, to both the cam cover ports, and to the acordian hose all into one hose correct? Thanks for the help guys...
 
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