HOW TO: *Properly* disconnect your PCV ...

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Kfred
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Post by Kfred »

I also run both my pcv and breather open to atmosphere, and have been for the past four years.

I just keep an eye on the condition of my oil and change it as needed. This may not be the best setup, but it is the easiest lol.
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Post by sdaigle240 »

bah might as well add my update.

i ditched the exhaust evac. who ever it was, was right. in boost its not doing anything. whoever it was had valid points and testing, and it got me thinking beyone basic theory. i begain to notice the only time my car would "dump the blow by" was as soon as i went back to vac. disconnected and it stopped, proof enough for me. i actually ditched it so i could take emissions, it was a blessing, after disconnecting it, the slash (with check) was still pulling in fresh air and allowed me to slam dunk the test.

currently im running PCV and VC to atmosphere, pretty much just b/c brian is and has been for so long. i def think the oil contaminates faster and needs to be changed more often. then again considering how hot i run it, its got to be changed often anyway.
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Post by MTX450 »

sdaigle240 wrote:bah might as well add my update.

i ditched the exhaust evac. who ever it was, was right. in boost its not doing anything. whoever it was had valid points and testing, and it got me thinking beyone basic theory. i begain to notice the only time my car would "dump the blow by" was as soon as i went back to vac. disconnected and it stopped, proof enough for me. i actually ditched it so i could take emissions, it was a blessing, after disconnecting it, the slash (with check) was still pulling in fresh air and allowed me to slam dunk the test.

currently im running PCV and VC to atmosphere, pretty much just b/c brian is and has been for so long. i def think the oil contaminates faster and needs to be changed more often. then again considering how hot i run it, its got to be changed often anyway.
Pulled out the PCV valve and just running to atmosphere?
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Post by Matej »

Why do you fellows say that just capping the ends on the bottom of the intake runners with rubber vacuum caps is not a good idea?
Is it because the turbo pressure can blow them off, or is there another reason?

I plugged mine off with rubber vacuum caps, since the hoses that are on there stock are rubber. However, my motor is just an N/A KA, so there should not be any pressure on them, only vacuum. Is plugging them off with just rubber plugs alright on an N/A motor, or is it still a bad idea?
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Post by orion »

^^^ Rubber gets old and cracks, especially with heat. I had a couple sets on my intake manifold before I drilled-and-tapped it, and every year or so...I'd have to replace one.

It was usually in a gas station parking lot, in the rain :) .

Silicone vacuum caps will hold up better, but they can still pop off under boost.

In the very least, if you're gonna just stay N/A and cap them...buy quality silicone vacuum caps.

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Post by Matej »

Thank you, now I know. I will look for silicone caps online.
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Post by s14BEAST808 »

Ok im lost.. the PCV isnt that the purge control valve? Where is this located? I thought it was under the 3rd intake tube on the mani????
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Post by revolutionz_s13 »

Positive Crankcase Ventilation.
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Post by s14BEAST808 »

uhhh what? LOL
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Post by schmauster920 »

Yeah those rubber caps lasted me a few months on N/A, the ends split and they are worthless.

Those cheap soft plastic ones seem to hold up alright... I put a zip tie on them, silicone sounds better though
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Post by s14BEAST808 »

Question... Why does anyone even mess with this stuff? Simply because it gets old and brittle and its too expensive to replace? Or dos it cause engine problems? Wont you still have error codes after removing and plugging this ****?
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Post by revolutionz_s13 »

because the stock pcv system is not enough for a KA turbo'd
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Post by TryingToTurbo »

revolutionz_s13 wrote:because the stock pcv system is not enough for a KA turbo'd
lol, wtf are you talking about?

It's a check valve that vents crankcase pressure. How do you have a pcv that "isn't enough"?

The reason people take it off is because it cleans up your intake manifold, and it's one lest thing to worry about going wrong....
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Post by revolutionz_s13 »

right, it also doesnt scavange any crankcase pressure under boost...the positive manifold pressure pushes the pcv valve shut. thats what i mean.
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Post by TryingToTurbo »

revolutionz_s13 wrote:right, it also doesnt scavange any crankcase pressure under boost...the positive manifold pressure pushes the pcv valve shut. thats what i mean.
As does any PCV setup. That is how they are designed. The only time they experience full open is at partial throttle. Low load and high load the valve is closed, or very close to it. Its how it works.
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Post by s14BEAST808 »

if this valve was to get stuck open or closed, would this cause idling and revving problems sometimes? Especially after car is warm
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Post by s14BEAST808 »

If you have a 1996 Nissan s14 KA24DE, the pcv valve is located up and behind the alternator, and in between the oil filter. A metal Check valve. It runs along with the IAVC tube. Getting in there is a bitchhhhh. I suggest you buy a bottle of coolant as well. The upper and bottom raidator hoses need to be removed, (it helped me a bunch)
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Post by irritatedmax »

s14BEAST808 wrote:If you have a 1996 Nissan s14 KA24DE, the pcv valve is located up and behind the alternator, and in between the oil filter. A metal Check valve. It runs along with the IAVC tube. Getting in there is a bitchhhhh. I suggest you buy a bottle of coolant as well. The upper and bottom raidator hoses need to be removed, (it helped me a bunch)
That goes for all DOHC KA's.
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Post by dakar318 »

damn this PCV subject has been the hardest thing to research for a 240 LOL!

ok i have 1 question, and im hoping someone doesn't give me a NICO answer ;)
first off, we have no emissions in the great state of alabama, also i dont care about puking out my blow by all over the place. Also I running megasquirt so no maff and nothing else to worry about.

i would rather not run a catch can if possible.... this is more or less a weekend warrior i beat on.

Ive got my intake manifold blocked off to the tree. and i just left the PCV hose hanging. The valve cover has a rubber hose that runs to the side of the engine bay completely open.
now what is the quickest and easiest way of getting my crank case to vent?
remove the PCV fitting on the block and drill it out or replace w/ open one?

im hoping this will finally rid me of my excessive smoke between shifts.


Image i FINALLY found a picture of the pcv valve lol.
Last edited by dakar318 on Thu Feb 24, 2011 8:34 am, edited 1 time in total.
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Post by supakat »

order a catch can and connect both the valve cover and pcv to a y adapter and go to catch can. take secondary catch can line to pre turbo preferably after maf if running draw through.

I will be doing this with can but venting to air.
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Post by TryingToTurbo »

s14BEAST808 wrote:if this valve was to get stuck open or closed, would this cause idling and revving problems sometimes? Especially after car is warm
I doubt it. I know people who just run a straight through fitting here with no check valve into a catch can.
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Post by TryingToTurbo »

supakat wrote:order a catch can and connect both the valve cover and pcv to a y adapter and go to catch can. take secondary catch can line to pre turbo preferably after maf if running draw through.

I will be doing this with can but venting to air.
If you plan to vent to air, you should remove the check valve and put in a straight fitting. With my supercharger this is what I am going to do becuase of how my intake works, I will always be pulling high vacuum with it (regardless of throttle), so it is acting like a straight through fitting all the time anyways....

The PCV system is designed to fully open at high vacuum situations such as idle and cruising, which is 90% of the driving you do.

Under low vacuum and boost, the PCV closes to air doesn't revert back through the PCV.

So, if you keep the check valve and vent to air, it will just always be closed. Well not fully closed, but BARELY open. Due to this reason, youll get excessive blow by when cruising (ask me how I know =])... I am going to run a straight through fitting so that it can be flowing freely to the atmosphere during cruising and idling situations. Then under boost it will still be full open, but you don't have to worry about air going back in becuase it's vent to air and not hooked up to your intake system.

Incase you don't believe me on how a PCV system works, google it. It has a spring in the check valve so it closes anytime other than high vacuum which pulls against the spring.

Good luck guys. Hope this helps clear up some confusion.
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Post by gtrpryde »

Not sure if this has been posted, but has anyone used an exhaust driven crankcase vent setup like this?

http://www.summitracing.com/parts/SUM-1 ... mage=large.

I will be going this route next round of mods to my kat
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Post by supakat »

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Post by 240sxvaj »

http://forums.nicoclub.com/pcv-set-up-t366874.html

Here's some researching i did a while back. its been more than 3years since i ran this set-up and my air/oil separator has been collecting blow by fuel flawlessly, preventing dirty blow by fuel from going to intake manifold-then to combustion chamber.

Theres an alternative by using pumps or exhaust pipe as a vacuum source to get the circulation for the pcv system to work properly, but most people keep on thinking that the pre-turbo pipe is a good source of vacuum.
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Post by Aaj2k5 »

Thats the setup I am doing with a high quality air compressor air/oil seperator (already have), however I haven't seen anything about people using a single seperator with a fitting tapped into the VC, a fitting where the PCV is, coming to a Y-block on inlet and the outlet going to mcmaster check valve to pre-turbo.

I can't see any issue with it, but I haven't done endless hours of research on it either.
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Post by zlatsky »

this thread should be in the master tutorial section. it really helped with my motor build.
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Re: HOW TO: *Properly* disconnect your PCV ...

Post by rn240sx »

orion wrote:And the proper way is NOT to just remove the 4-into-one deal, and cap each bung with a vacuum cap. They will leak. They crack, then leak. They pop off.
thats what i did and 3 yrs later, all 4 vacuum caps are still there, the clamps are still on and NO vacuum leak, idle is great :-)
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