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Pcv

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Beans

Addicted CEG'er
Joined
May 4, 2006
Messages
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Location
Plymouth,MI
Just looking for my best option on my 3L. Stock PCV Doesn't seem to be working.

My car seems to be burning a bit of oil only on start up though, I pulled my UIM off and it was SOAKED in oil, i mean a lot, especially for the short time i have driven the car. so my first thought it was the PCV. Cleaned it up the UIM and ordered a replacement.

I thought i could get away with just replacing the original with a new one but.. No go. Same deal.

Talking to TRicker he says the 2.5 PCV is basically too small for the larger displacement of the 3.0...
He gave me some good advice, but id like to see some other options/opinions.



1.) Is there a different PCV valve i can use? Without changing Valve cover? or the black crank vent box thing?

2.) Should i pick up a catch can?

3.) Should i get rid of this 'T' Setup? Let the Gas tank vent thing be there by it self.. and relocate the PCV stuff to... the EGR block of plate?
http://img.photobucket.com/albums/v254/Sp[PkF]Beans/pcv.jpg?t=1253932795

Input please, Thanks.
 
beans do you have the 3L "black box" on that? if so, it's got a PCV built into it, right where the hose connects. if you are running two PCV's in line, that could be the issue. many people run the stock PCV without issues, but i could never get it to work right.
 
Nope, motor came with that plate thing that covered the hole. Using the SVT black box, and SVT PCV.

Considering picking up a lightning PCV, We'll see though.
 
the PCV valve itself doesnt prevent oil from being sucked into the manifold, thats the air/oil separators job (the black box). your only real options are to replace the stock separator with a new one, or install another separator inline (which would be a catch can of some sort). I currently have an extra separator inline on my stock PCV setup and im amazed at how quickly it fills up. I have to empty it about every 1000 miles or so, but my intake is still as clean as it was when i last cleaned it.
 
basically its a splash guard that has some mesh inside it to keep the oil from passing through there. the crank moving causes pressure from the moving air (elementary stuff, i know, but some people never thought about PCV before)

the PCV valve itself is just a little ball for the most part, inside that round housing. when the engine creates vaccum it will suck that ball back so it seals off the hole in the PCV. when the rpm goes up (or throttle goes open, releasing the vaccum pressure from closed throttle) it will force the ball back out enough to allow the crankcase pressure to release. this is then routed into the engine again as it's unmetered air it has to go behind the TB.

with the 3L displacement, a 3/8" pcv line is too small and the crankcase pressure at idle can even let the ball be pushed back and oil can start to creep up to the pcv itself through the 3/8" line. then once you hit the throttle and the intake starts to suck, it will suck that oil that creeped up the line into the intake manifold. this is no fun.

and all of this explanation is why that previous answer of "not very well" is a valid answer.
 
Well... the Lightning PCV is identical In it's In/Out to the Contours (from what i can tell) How do you explain that?
 
Beans said:
Well... the Lightning PCV is identical In it's In/Out to the Contours (from what i can tell) How do you explain that?
Click to expand...
He's actually got the PCV operation backwards. under high vacuum (low throttle, idle, etc) the plunger in the PCV valve is pulled against the spring and opens allowing the blowby gases in the crankcase to flow into the manifold and then get burnt with the rest of the A/F mizture.

the problem is not that the PCv valve itself is to small. the problem is that the stock 2.5 air/oil separator isnt efficient enough for the extra blowby that comes with more power. this allows oil to get past the separator, into the lines, and then gets pulled into the intake via vacuum.

i suspect that the reason this is problem for even stock SVTs is because the separator was designed originally for the regular 2.5L. going to a 3L and making even more power just makes the problem worse.


the biggest difference between valves that have the same outer dimensions is the strength of the spring, the size of the orifice, and how well it seals under low vacuum/pressure (pressure is obviously only seen in boosted applications).
 
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