My PCV Valve Statement

[SyTyJedi]

Print this out and put it somewhere, these are the rules of PCV...there is a question at the bottom.

-DO NOT put a PCV valve on the drivers side vavle cover

-DO NOT put a breather on the oil filler cap

-DO put a breather in the grommet at the rear of the vavle cover if you wish (cleaner and almost necessary with aftermarket intake, unless you want to run a line to other side of the motor)

-DO NOT put breathers on either one of the PCV valves on the passenger side valve cover, they WILL NOT function properly.

-DO NOT route the PCV lines into a catch can with a breather on top

-DO route the PCV lines into a CLOSED catch can ONLY IF it has an outlet hose and route that to the proper location

-DO put clamps around the PCV valves in the "T" connector that they sit in to keep them from popping out.

These are the rules. If you do not follow the rules, expect oil leaks, oil residue everywhere and more hassle than if you left it alone.

If you want to put a catch can (like GReddy) on one of the PCV valves, put it inline with the one going to the throttle body, the most oil vapor goes thru there since you engine is always in vaccuum. I had hardly any oil coming thru the line going to the turbo inlet to vent under boost. Most of the residue would stay at the beginning of the line and never make it to the turbo anyway.

Question: Why do I see pictures of built motors with NO pcv valves or the PCV system routed incorrectly? I've seen this on a number of built motor trucks now...why are people ignoring this?

Just FYI...



Tyler

 

[JoeLutz]

If you want to put a catch can (like GReddy) on one of the PCV valves, put it inline with the one going to the throttle body, the most oil vapor goes thru there since you engine is always in vaccuum. I had hardly any oil coming thru the line going to the turbo inlet to vent under boost. Most of the residue would stay at the beginning of the line and never make it to the turbo anyway.

Question: Why do I see pictures of built motors with NO pcv valves or the PCV system routed incorrectly? I've seen this on a number of built motor trucks now...why are people ignoring this?

Just FYI...

Tyler

Mabey I am reading this wrong, but are you saying the engine is always in vaccum at the PCV port from the throttle body? When under boost the intire intake is pressurized including the throttle body.

Which leads me to a guestimate to your question. I believe people running very high boost levels are concerned that the pcv valve, being a one way check valve between the throttle body and crankcase, may not be able to prevent this high pressure from flowing the wrong way through the PCV valve into the crankcase, thereby creating a higher crankcase pressure, which is what the PCV valve is supposed to prevent in the first place.

 

[Tooky]

On 2001-12-03 11:55, Engulfing Darkness wrote:
Question: Why do I see pictures of built motors with NO pcv valves or the PCV system routed incorrectly? I've seen this on a number of built motor trucks now...why are people ignoring this?

I see pictures of built motors with a big orange FRAM oil filter on them too.. obviously I have no explanation for that either. (Anyone know?)

Thanks for the PCV post Tyler, good reference. Let me add one stupid one of my own:

DO NOT try to blow or suck through used PCV valves with your mouth to test if they are still good. You may feel sick or have an awful taste in your mouth for hours, not that I would know from first hand experience :roll:

 

[Daron]

On 2001-12-04 02:28, TookyCat wrote:

On 2001-12-03 11:55, Engulfing Darkness wrote:
Question: Why do I see pictures of built motors with NO pcv valves or the PCV system routed incorrectly? I've seen this on a number of built motor trucks now...why are people ignoring this?

I see pictures of built motors with a big orange FRAM oil filter on them too.. obviously I have no explanation for that either. (Anyone know?)

Thanks for the PCV post Tyler, good reference. Let me add one stupid one of my own:

DO NOT try to blow or suck through used PCV valves with your mouth to test if they are still good. You may feel sick or have an awful taste in your mouth for hours, not that I would know from first hand experience :roll:

The proper way to check for operation of a PCV is to shake it. If it rattles it is likely ok. However, if I gotta shake them, I just replace them.

 

[Bobalouie]

joeelutz,

The stock setup has the PCV valve tied into the intake tract that leads over the fan shroud. That part of the system is always under vacuum, the pressurized side of the system is after the turbo.

 

[Daron]

On 2001-12-04 16:03, Bobalouie wrote:
joeelutz,

The stock setup has the PCV valve tied into the intake tract that leads over the fan shroud. That part of the system is always under vacuum, the pressurized side of the system is after the turbo.

There are two PCV's.. One is ported near the throttle body and under vacuum conditions will evacutate the crankcase via the passengers side valve cover. Kick into boost, that PCV closes, the the other one opens, taking advantage of the newfound vaccum before the turbo, in the crossover. This second one shares the tube on the passenger side valve cover and evacuates in a similar manner as the other one. One is meant to operate under vacuum (manifold reference) and the other is meant to operate under boost conditions.

_________________
Daron
1992 Typhoon Blue/Gray
1991 Syclone Best 1/4 12.42 @ 106.1
Member Of Freakin' Ohio (MOFO) SyTy

<font size=-1>[ This Message was edited by: Daron on 2001-12-04 16:45 ]</font>

 

[SyTyJedi]

On 2001-12-03 23:40, joeelutz wrote:

If you want to put a catch can (like GReddy) on one of the PCV valves, put it inline with the one going to the throttle body, the most oil vapor goes thru there since you engine is always in vaccuum. I had hardly any oil coming thru the line going to the turbo inlet to vent under boost. Most of the residue would stay at the beginning of the line and never make it to the turbo anyway.

Question: Why do I see pictures of built motors with NO pcv valves or the PCV system routed incorrectly? I've seen this on a number of built motor trucks now...why are people ignoring this?

Just FYI...

Tyler

Mabey I am reading this wrong, but are you saying the engine is always in vaccum at the PCV port from the throttle body? When under boost the intire intake is pressurized including the throttle body.

Which leads me to a guestimate to your question. I believe people running very high boost levels are concerned that the pcv valve, being a one way check valve between the throttle body and crankcase, may not be able to prevent this high pressure from flowing the wrong way through the PCV valve into the crankcase, thereby creating a higher crankcase pressure, which is what the PCV valve is supposed to prevent in the first place.

They still have to get it out of the motor somehow...I haven't seen any PCV valves venting before the turbo either. If they are worried about crank pressure, they need to vent it properly...will probably make it live longer and make more power.



Tyler

 

[JoeLutz]

I understand what all of you are saying about the two pcv valves, so that when the manifold is under pressure, there is still some vacum from the air intake leading to the turbo, hence the two pcv valves. In fact I just changed both of mine. I must have just misread Tylers post, I thought he was saying that the Intake manifold is always in vaccum which is obviously not the case during boost. Sorry about the confusion.

The wildest crankcase ventalation I've seen is on a rail dragster wher there were two large vent hoses comming from both valve covers to the headers of all things!! The vent tubes went into the header at an angle near the open end of the header in such a way as to make a venturi effect to create a vaccum in the hoses to pull out the crankcase gasses. Very cool.

 

[SyTyJedi]

That is very cool.

The Dumler's have their PCV valve outlet going to the downpipe after the 02 sensor. I need to drive over and see if they still have it rigged up that way.



Tyler

 

[Syclone#892]

My truck has that setup you are talking about with the tube going into the downpipe. If you look through Summit or Jegs catalogs they sell them for like $50.

 

[syntax]

im very interested in the downipe setup seeing on how my pcv system is unhooked right now(tube just goes to normal air), although id be very wary about 1000 degree exhaust gases making it into the valve covers, is the actually valve able to stop thehigh pressure exhuast gases(i assume they are under more pressure than the air intake), anyone have any more info on this system? is the exhaust system under anough pressure to pull the crap from the crankcase? thanks for any info

 

[syntax]

im very interested in the downipe setup seeing on how my pcv system is unhooked right now(tube just goes to normal air), although id be very wary about 1000 degree exhaust gases making it into the valve covers, is the actually valve able to stop thehigh pressure exhuast gases(i assume they are under more pressure than the air intake), anyone have any more info on this system? is the exhaust system under anough pressure to pull the crap from the crankcase? thanks for any info

 

[syntax]

double post sorry

 

[Mephisto]

ok so then whats the deal with the mini K&N filters? ive seen some of them on bulit motors... arent they plugged into the PCV valves?

 

[JoeLutz]

On 2001-12-07 00:45, syntax wrote:
im very interested in the downipe setup seeing on how my pcv system is unhooked right now(tube just goes to normal air), although id be very wary about 1000 degree exhaust gases making it into the valve covers, is the actually valve able to stop thehigh pressure exhuast gases(i assume they are under more pressure than the air intake), anyone have any more info on this system? is the exhaust system under anough pressure to pull the crap from the crankcase? thanks for any info

The way this works is that the tube going into the exhaust is at such an angle and protrudes into the exhaust pipe so that the flow of the exhaust past the tube actually creates a vaccum in the breather tube. Much like an air paint spray gun works. I'm not sure if it would work on a vehicle with full exhaust though, becuse the back pressure would actually cause a back flow of exhaust into the crankcase.

 

[UNIsackV6]

On 2001-12-03 11:55, Engulfing Darkness wrote:
Question: Why do I see pictures of built motors with NO pcv valves or the PCV system routed incorrectly? I've seen this on a number of built motor trucks now...why are people ignoring this?

You don't really need a traditional PCV set up when you go all out, basically there is a valve in one of the tubes that come out of the valve covers and you slide the small KN Filter over that. The valve allows the air to only move one way...that rail dragster set up sounds nifty, I read an article on a V8 with 18 degree heads making like 650HP and he put on an external crank driven vacuum pump to remove vacuum under acceleration and he picked up ~70HP! and the motor was normally aspirated! Image what this might be able to do for for a built turbo V6, hmmm maybe I'll have to give it a shot...it really seals the piston rings to the bore of the block and virtually eliminates any oil blow-by making for a much more consistent and clean combustion...

I see pictures of built motors with a big orange FRAM oil filter on them too.. obviously I have no explanation for that either. (Anyone know?)

Thanks for the PCV post Tyler, good reference. Let me add one stupid one of my own:
DO NOT try to blow or suck through used PCV valves with your mouth to test if they are still good. You may feel sick or have an awful taste in your mouth for hours, not that I would know from first hand experience :roll:

Tookster, some of your posts crack me up :wink: That big Orange Fram HP6 oil filter is most likely from my truck. Why do I have this? Because I have an Dry Sump oiling system which holds nearly 3 gallons of oil. When you run an external oil pump it is imperitive that you keep the oil clean as you dont'want to clog up the pump. The small filter probably would have worked but it would have been the bottleneck in my system and I don't like bottlenecks they're like carnies...circus folk you know...they have really small hands :wink: I hope to have more photos up soon on http://www.chitownsyty.com of everything completed.

_________________
Ryan
'92 Odd-Ty
Engine by Ultratech
Drivetrain by Roadmaster
Every other wacky thing compliments of Rich "Pablo" Eartly and Brian "Rastaman" Green

<font size=-1>[ This Message was edited by: OddfireV6 on 2001-12-10 14:25 ]</font>

 

[rockvillespeed]

the header crankcase evac systems are absolutely not- repeat - not - meant for street motors - first, yes, back[ressure renders them far less effective. also, they're meant to work at wot - what happens when u close throttle at hi rpm? remember, guys, a motor is an air pump - nothing more.
i would not recommend this.
manufacturers all state same.

 

[Methuselah]

Ive read through everything a search on "PCV" turned up, so I grasp the concepts....but Im still missing one thing.

First, let's pretend for the moment that we dont care about EPA regulations and keeping Mother Nature happy.

Second, let's remove the entire PCV system...so there are NO PCV valves now.

Third, let's put catch cans into the grommets in the valve covers and put filters into those. So, there are two breathers, one on the passenger side and one on the driver's side.

Now let me explain why I am being so anal in my setup for the question. The PCV valve statement is true and accurate, so long as you intend to keep positive ventilation of your crankcase, and are concerned where those gases go. That is, you dont want to vent them to the atmosphere.

In the thread "K&N Breather" crsurf1 mentioned that he replaced the PCV system in pretty much the way I described above. SyTyJedi responded with "This will not work" because "vacuum pulls them open to allow pressure to escape the crankcase." Thats all well and good, but if there are NO PCV valves, just breathers, then excess pressure in the crankcase IS escaping.

I realize there is now no guarantee that there is a pressure diffferential between the crankcase and atmosphere, but I imagine a natural convection will remove gases from the crankcase before they can cause problems, say, to your oil.

So the question is....am I wrong? And if so then ...why?

Thanks.


________
As50

 

[SyTyJedi]

Good idea - but the catch cans will mostly fill up with condensation and very little oil. I actually tried this last year.

Yes, vapor will escape the crankcase, but not as fast as it needs to. It was designed to be SUCKED out, so it should be.

NOW - if you get a cool catch can, like the GReddy one, with two ports on it you can put it inline with the PCV valves and their destination ports. Any vapor will most likely get trapped in there and the clean air makes it back into the intake stream.

It will help some, but you won't pick up any power to justify the cost probably. Hey! That sounds like something I need to spend MY money on! :smile: I'll probably end up doing it, just to make things as effecient as possible. I can get a pretty good deal on them, and they are among the best looking ones out there.

PCV just isn't for emissions, but for the life of the motor and it's associated parts.

Good question... :wink: