Basically that's an oil catch can. Personally, I wouldn't run anything into the intake charge that doesn't aid in the combustion process, ie. air, fuel, meth/water injection, nitrous, etc. Though this is better than the stock set up, I suggest if your going to mod your PVC system, vent that **** to the atmosphere. Either run just breathers, or if your worried about any oil spray, run a catch can to a breather.

 

yea I just thought this would be easier than running an inline catch can.

 

Run breathers off of each valve cover and the oil filler tube.

 

Do you have any pics of this setup?

 

What all do the breathers do

 

They vent crankcase/blow by gases out of your engine. Your stock set up routes this stuff back through your engine via the intake charge. That's why you see threads with people and oil all over their CMCP butterflies. It's really not that good to run that stuff back through your engine, but the EPA makes us do it.

 

Correct, that's the exact set-up I've got. I get very little oil blow-by from the breathers. I'm talking about very minimal. It's almost not even worth mentioning. Thanks for the assist 07 Boss.

 

Okidoki, I'm sick of trying to decide on catchcan vs. breathers: been looking at the K&N ones you guys run, it's just one on each PCV valve and one on the filler tube, right?

Stupid newb-like questions:
Where did you guys get yours from?
Are these them?
Do you have to do anything to make the oil filler breather work?
Why do you run the oil filler breather?

 

The rubber based ones are the right ones. I think it's 1320 and 1340. They are 2 different sizes on each side. We run the oil filler breather to vent more pressure. Without it you may get some oil spray, you may not. The oil filler breather comes from Central Florida Motorsports.

 

well im only running the two, one on each side minus the oil fill breather...and I get alot of dripping from the passenger bank. drivers is fine, so Im going to install the oil fill breather. this should fix my problem, i think its because the tube on the passenger bank is narrower not allowing the gases to vent fast enough.

 

i have all 3 breathers as well. i was getting blowby out the passenger side, very little. i changed my oil from 5w20 to 5w30 and also make sure the breathers are clean (clean them every month), and now i have no blowby. i have also had the moroso oil/water separator, and the steeda separator, and i like the breathers the best bc of the look and its easy to clean and i like the idea of venting out the pressure.

the K&N breather sizes are 3/8 for the passenger side and 5/8 for the driver side.

 

If you run a oil catch can on the driver's side, doesn't it go on that vacuum line from the valve cover to the intake manifold? So instead of running that line, you all are putting a breather on the valve cover and then stopping up the intake manifold end? May need to look into doing this again, I've been pooling a good bit of oil in the butterfly.

 

Yeah, I just used a couple of vacuum caps from Napa and put them over the nipples on the manifold and CAI. No oil in the intake.

 

you must either vent both sides or plumb in a oil separator in the driver side pcv line with it still being connected to the intake. the pcv line on the passenger side is where the air goes in, and the driver side pcv line sucks the air out into the intake, if you look inside both lines, the passenger side has no oil but the driver side does. if you just do one side it wont work that well. or you could run both sides into catch can breathers.

 

I don't think that is right. Both sides vent crankcase gases out. The engine doesn't pull air in through the pcv system. I don't know where that came from. PCV and the PCV valve deal with Positive Crackase Ventilation, there is no vacuum to suck air in only Positive pressure, and even if there was, why would you want to suck air into your crankcase? That makes no sense at all. If anything, some people run a vacuum pump to there pcv system to help draw out gases.

Because one side has more oil in the line doesn't mean anything except that side is blowing more oil than the other. In fact, with breathers you will probably get more oil spray from the passenger side than the driver's side.
Do you want to know why there is more oil in the drivers side line? Look where the PCV is hooked up to on both sides. The drivers side is directly into the manifold and has definite manifold vacuum to help suck out the gases. The passenger side is connected to the CAI where there is some vacuum caused by the velocity of air flowing by it (Benouille's principle), but not as much. Think about it, at idle your vacuum in the manifold is pretty high, but with the least amount of air flowing through the CAI, the vacuum will be at it's lowest point. More vacuum, more gases, more oil residue.

And don't leave it connected to the manifold. There is no reason, except for the EPA, to pump these gases back into your intake charge. In fact adding these crankcase gases back into your intake is bad for your engine, performance wise. It displaces oxygen from your air fuel/mixture. Less oxygen, less fuel burned, less power. It may also in fact lower your octane which is not good either.

 

K, right now I know I have an oil separator running from the intake arm to the passenger side and a breather on the passenger valve cover. To fully get rid of the pooling oil, it would be best to seal off the line running from the driver valve cover to the manifold with a seal and breather/oil catch?

 

Yes. You don't want to run anything back into your intake charge. Whatever breather/catch can set up you run, vent it to the atmosphere to prevent any oil that does get by your set up, from going back into the intake.

I think the best set up is the one that was on the first page of this thread. Run both sides to a catch can that goes into a breather and vents it out. I went with just breathers because it is a cleaner set up and looks nice. I do get a slight film of oil on the fender well on the passenger side that I just wipe up every once in a while.


Edit: Sorry Animal, I just looked at the first page and didn't see the set up I was talking about. it must be in another thread. I think I was talking to 07 procharger (stroker) about it. It was a nice catch can with 2 inlets on it and a breather on top. I saw one mounted to someones fender and posted a pic of it to whomever I was talking with. I'm pretty sure it was 07 stroker, maybe PM him and he can remember where we talked about it. If it wasn't him he'll just go huh?
If it wasn't him PM me later and I will see if I can find it for you. Right now I have no time, going to go golf and then play poker.

 

If you baffle the driver's side valve cover and seal the line going into the manifold, won't that loss of pressure affect ring sealing?

 

No. Rings dont rely on crankcase pressure to seal...they rely on internal combustion to seal.

 

I edited the post.

 

:lol thanks

well it isint vaccum its pressure...from the crankcase, but anyway, no the only reason that **** is on there is for emmisions...they want youto reburn the crankcase gasses instead of venting them...well **** that...atomized oil and nitrous dont mix...i like my intake where it is

good to know, I'd really love to get this oil out of my supercharger fins and intake butterfly!

 

well it isint vaccum its pressure...from the crankcase, but anyway, no the only reason that **** is on there is for emmisions...they want youto reburn the crankcase gasses instead of venting them...well **** that...atomized oil and nitrous dont mix...i like my intake where it is

 

the passenger side tube lets metered air in from the intake tube, then the metered air is sucked from the crankcase into the intake.

http://www.supersixmotorsports.com/pdf/PCVBypass.pdf

PCV Bypass
Theres a right and a wrong way to bypass your PCV (Positive Crankcase Ventilation) system. Before we
show you the how to, lets first understand the function of the PCV system. The PCV system is intended to
relieve the crankcase of any positive pressure by allowing it to vent through the free flow of air, either into or
out of the crankcase. Prior to advent of emissions, the crankcase was just vented through a breather on the
valve covers or intake manifold to the environment. Emissions requirements necessitated a “cleaner” way to
vent the crankcase to prevent the hot oil laden vapors from damaging air quality. That led to the inclusion of
today’s modern PCV systems. Current PCV systems are still pretty simple, consisting of an air inlet, a valve,
and an outlet. The air inlet (the vent tube) supplies filtered and metered airflow into the crankcase. The PCV
valve, which when opened by either internal intake manifold vacuum or positive crankcase pressure, vents
into the intake manifold, allowing the now oil contaminated but otherwise filtered and metered crankcase ventilation
airflow to be consumed by normal combustion processes.
Its important to note 2 significant issues:
1) The crankcase ventilation airflow is metered since the vent tube is located after the MAF. Because the airflow
is metered, it must make it into the intake manifold to assure that the air/fuel ratio is correct. Therefore, if
we bypass the PCV system, it must done in such way that no unmetered air can reach the intake manifold, for
if it does, the air/fuel ratio will be adversely affected. Similarly, any metered airflow in the PCV system must
make it all the way to the intake for the same reason. What this means is, if you bypass the PCV system, it
must be bypassed completely, both the inlet and the outlet air transfer paths must be blocked. You just can’t
block off one and not the other.
2) The PCV valve is intended to be opened by intake manifold vacuum (negative pressure), but can also be
opened by positive crankcase pressure. Therefore, whenever vacuum is present in the intake manifold, the
crankcase pressure will vent into the manifold and the ventilation air is “drawn” into the intake manifold
through the PCV valve all the way through the crankcase, vent tube, MAF, and air filter. Furthermore, when
positive crankcase pressure is present, it will be vented through the PCV valve into the intake manifold.
There’s no problem at all under most circumstances, but there can be very significant issues in certain applications,
especially if substantial cylinder blowby is present, if the PCV system is overly effective, or if supercharged.
Who needs to bypass the PCV system? In most applications, the PCV system works just fine, but certain hipo
applications may run better with the PCV system bypassed, even though your car will no longer be emissions
legal. In that case, the decision is yours, bypass the PCV or remain emissions legal? High compression
engines setup with low tension oil control rings are a real good application for PCV bypass. Engines with
poor ring seal and substantial blowby will also benefit because the incoming air charge will not be oil laden,
which effectively lowers the octane of the air/fuel mixture and increases susceptibility to pre-ignition, detonation,
etc. The 99-up models seem to have acute issues with overly effective PCV systems, just about every
intake manifold we’ve seen has been thoroughly soaked with oil. In fact, Ford issued a service bulletin for
valve cover replacement reportedly using revised baffling to minimize oil contamination of the air charge.
However, we think that has been ineffective. More on that later.
OK, lets do it.
94-98 3.8L V6 Mustang using dual breathers: Remove the air inlet tube that runs from the convoluted intake
tube to the driver’s side valve cover. Plug or cap the hole left in the intake tube. Insert a small .75” K&N
breather in the hole left in the valve cover. Remove the upper intake manifold, the PCV valve, and the line to
the port underneath the plenum of the upper intake. Insert another small breather into the hole left in the passenger
side valve cover by the removal of the PCV valve, and cap off the port in the intake manifold. Extend
the evap cannister purge vent line past the solenoid to a tee that you’ll instal into the primary vacuum line at
the upper intake manifold. The PCV system is now completely removed and blocked off such that the air/fuel
ratio is unaffected.
99-up 3.8L V6 Mustang using dual breathers: Remove the air inlet tube that runs from the convoluted intake
tube to the passenger side valve cover. Plug or cap the hole left in the intake tube. Insert a small breather
into the hole in the valve cover. Remove the PCV valve and line from the driver’s side valve cover. Cap the
fitting in the upper intake manifold and insert another small breather into hole left in the valve cover. Extend
the evap cannister purge vent line past the solenoid to a tee that you’ll install into the primary vacuum line at
the upper intake manifold.
94-up single breather: Remove the air inlet tube that runs from the convoluted intake tube to the valve cover
vent. Plug or cap the hole left in the intake tube. Cut off the tube an inch or so from the plastic valve cover
fitting, and cap off the valve cover fitting. Remove the oil filler cap and install a screw-on K&N breather. Disconnect
the line running from the PCV valve to the intake manifold at the PCV valve. Cap the PCV valve outlet
and plug the line. Leave the evap cannister purge line connected to the PCV valve line as it is.
You have a 99-up model with overly effective PCV system that contaminates the intake manifolds and impairs
performance? If you intend to leave the PCV system intact, here’s a potential quick fix that you may try. Remove
the PCV valve cover. Enlarge the drain back hole in the baffle. Stuff the baffle with coarse stainless
steel wool but don’t pack it too tightly. The steel wool should help by “straining” the oil from the air flow.
Lets talk about supercharged or turbo applications. We think the dual vent system is the way to go in any
high boost or blowby application because the general flow requirements through the PCV system are restricted
by the small size of the lines and the small aperatures of the vent and PCV valve. This is especially
critical on the 99-up models which already have PCV systems which may be seriously diluting the air/fuel octane
with oil vapor.
A word of caution regarding the use of one-way valves in the PCV system of supercharged applications. We
don’t recommend it. Here’s why. Lets say you have a problem with blowby that deposits oil into the compressor
inlet from the vent line, pretty common problem. Stop and remember how and why the PCV system
works. Engine vacuum (negative pressure) opens the PCV valve, and draws ventilation supply flow, i.e., metered
air, through the engine and into the intake manifold. Now, in boosted applications, the intake manifold
will be under vacuum only at very low rpms. Most of the time, the intake manifold will actually be under boost
and therefore will be under positive pressure. Therein lies the problem. Even though the PCV will open under
positive crankcase pressure, that positive pressure created in the crankcase by blowby is acting against a
greater or equal positive pressure in the intake manifold. When both sides of the PCV valve are at the same
pressure (pressure is acting on opposite sides of the diaphragm), there will be zero flow because the valve
can’t open. That means that you’ve now positively pressurized the crankcase by blowby. Now, the PCV system
has to act in reverse. The flow and pressure will be vented the wrong way through the vent line over to
the supercharger inlet. This is the point where one theory recommends the use of a one way valve. The theory
is to orient the valve to only allow flow into the crankcase, but not out from the crankcase. While that
might be acceptable on a really tight engine, the fact is that most supercharged engines run a fair amount of
blowby. The problem is, with the one-way valve installed, there is no path to vent the blowby, which is going
to pressurize the crankcase since there can now be no path to relieve the positive pressure except around
seals and gaskets, which will cause them to leak. Also, remember that positive cranckase pressure also
hurts performance.
The drawback to venting an engine’s blowby is that the breathers will eventually become oily and start to drip.
The answer is not pretty but it is effective. Periodically remove the breathers, wash them in solvent or K&N
filter cleaner to remove the oil, reinstal them, and wipe off your valvecovers.

 

^^ Awesome reading material, thanks for the coffee break!
That said, while you were right, they still recommend dual breathers and blocking off the PCV system completely. :shiftyeyes

 

On my brother's 62 Saratoga, both valve covers have tubing going to the bottom of the engine compartment, facing the rear of the car.
As you get up to speed, the air going around the tubes pulls (vacuums) the gases out the crankcase.
If you're sitting at a light, the gasses just stay there, no venting. But still no positive pressure to the engine.
Automatic rustproofing of the floorboards!

 

Onederful,
I do think I stand corrected. My understanding of how a PVC system works is based on my knowledge of older motors. And like your article states, "in modern pcv systems" there is an inlet of metered air after the MAF. I was apparently wrong in my assumption that all pvc systems were the same. Though I don't understand the reason for an air inlet in the pcv system, it goes against what I thought I knew about how motors worked, I guess there is one.
I am humbled by your knowledge and the thought that someone could teach this old dog a new trick. Reps to you my friend.

 

thanks for the reps. i'm just someone who cruises these forums, and learns a thing or 2 just like everybody else, and i like to share what i have come accross. i dont pretend to know everything, but i know i little something.

 

As for the caps... I need 5/8" and 3/8" caps, is that all, just two? The Oil breather doesnt require one does it?

 

Read 07_Stroker's comment: he only has the two PCV valve breathers without an oil filler cap breather and is getting excess spray out of the passenger side breather. He thinks it's because the passenger side breather has a smaller diameter neck and is going to get the oil filler breather to see if that helps any.

Apparently 07_boss and Nastystang don't get much if any spray out of their setups.

Seems like a decent way to go, much tidier looking than a catchcan too, IMHO.

 

No, all you need the vacuum caps for are the opposite ends of where the breathers go.

 

Thanks, doooooode!

 

No problem.

 

Just got my two valve cover breathers installed, will get the oil fill cap breather from C-F-M next week ($12 for cheapest shipping, seriously?!).

Question for 07_Boss and Nasty, is the drivers side breather supposed to go all the way to the base of the valve cover or stop at the lip that's 1/4 of the way up the valve? Just started raining or I'd post a pic.

 

i put mine just to the lip.


of the stem on the valve cover. (no **** just in case)

 

Good to know. I'm not worried about it falling off, just curious. It's on there pretty tight.


Yeah, no ****. :shiftyeyes
None of that here, my wife works quite well, thank you very much. :yes

 

I'll check mine in the morning. Can you drop me a PM so I don't forget? I'll take a picture of how I've got mine.