Pcv negative pressure?

[Rjhoward32006]

How much is too much?
I sealed my dipstick and all ports to the engine.
Installed a pcv catch can for roll-overs and now i'm getting what seems like a good amount of negative pressure. Will put a vaccum gauge in the dipstick tonight to measure. Do any of you seen this before once the engine is sealed up tight? Only bad thing i could think of it hurting is pulling oil away from pistons/ wristpins and things like that because of not as much splash affect?
Someone?
Anyone?

 

[gottagofast]

You can't pull oil away from anything with crank case vacuum

It will likely help the rings seal better tho

 

[Rjhoward32006]

Thats just what the drag racers are saying it does if it gets to high.
Starves the wrist pins and bottom of pistons for oil. As they are not pressure fed like the rods and bearings.
Aslo claim it makes it harder for the oil pump to suck the oil because the pressures are fighting each other.

I should also me tion motor is fresh and only has about 12k miles on it.

 

[al1tonyota]

Different pcv' shave different amounts of vacuum never seen one that had the amount of flow though? ??? When you say you sealed all ports do you mean you don't even have crank case breather? Gotta get fresh air in there!

 

[kturner]

What type engine is this ?

 

[Rjhoward32006]

Should be getting air from blow by past the rings?

This is a 22re

 

[gottagofast]

Oh wait.. So you have a pcv hooked up but no vent?
I'd change that.... Vent it to the air filter

 

[Rjhoward32006]

Correct if i vent it anywhere it has to be post afm so it is not an un metered air leak. Which is what i'm trying to avoid doing because i'm tired of it hydrolocking when rolled. But when you install this "vent" like factory after the afm it kills all negative crankcase pressure and goes to more of a posotive pressure. And i dont like that either

 

[gottagofast]

Uhhh... Post afm would be vacuum.....
The crankcase should be vented pre afm or to atmosphere...

It's not an unmetered anything because it isn't part if the equation

If it's in the air filter then yes it gets burned but it goes through afm first so it is metered.

 

[Rjhoward32006]

Yes on a 22re there are ports behind the afm that are non vaccum ports, for this reason. If you take the hose before it it sucks ambient air in and goes through pcv creating an unmetered air fuel mixture, the idle changes dramatically and it isnt happen. Same happens if you take the oil cap off yada yada yada. And most people dont realize this because the dipsticks and everything else leak air and are not sealed properly. And on a stock 22re the front valve cover hose runs to one of these post afm non pressure ports but when you flip it fills the intake and cylinders plus it takes away your vaccum affect and causes a positive crankcase pressure not enough to be badly concerned with but over time causes seals and such to leak.

I want negative pressure, i just dont if i have too much.

Thought someone might have played with this before.

 

[al1tonyota]

Lots of confusion it seems in this thread only way you are getting vacuum on the pcv to work right is after the throttle body the afm and pre tb only have vacuum when the throttle plate is opened, this is also the only time the pcv pulls vacuum (because of the drop in intake vacuum) If you put a catch can on the breather with a seperate air filter it won't get into the intake at all. The catch can will give somewhere for the oil to go but won't be able to leak out.

 

[Rjhoward32006]

I will try and clear things up when i can take pictures and readings a 22re works slightly different from what gottagofast is thinking.

And i have changed it from factory to make negative pressure in the crankcase instead of trying to control positive pressure as the factory pcv does. Its better for the engine seals and such. Just think i might need to lower this pressure a bit.

I know i cant be the first oerson on here to do this. Drag racers use mechanical or electric pumps to purposely put a vaccum on the crankcase.

 

[TBItoy]

Re:





If you take the fresh air intake hose off, cap the barb fitting on the TB, and put a separate small filter on the valve cover port (oil will run out when flipped over), Or a hose with the filter below the engine (oil will drain out if you are on your side, but not upside down), or hose loop that goes below the oil pan with the filter above the engine and towards the back of the engine (oil will not be able to leak out at all).

EDIT: If you are still running stock EFI with the Air Flow Meter, then run a hose loop around the engine, below the oil pan, then hook it back to the stock location on the throttle body, that way a bunch of oil won't drain into your intake when you are upside down, You can put a catch an on it if you want, but whatever oil gets into the line will be sucked back into the valve cover when you crank the engine, so it's not a big deal.


Hook a hose to the pcv to a catch can before you hook it to the intake, that way when you flip over (or lay on the pass side in the case of a 22re) the catch can creates a reservoir to hold the oil that drains out so it doesn't get into the intake.


Then if you are upside down or sideways for an extended period, you can drain the catch can and dump the oil back in the motor

 

[Rjhoward32006]

Almost correct on a 22re the fresh air is actually behind the throttle plate but does the same it is hooked to a non vaccum port to get fresh air that is already calculated into your air flow for the engine. If you let this hose suck from anywhere before the throttle plate or ambient air it is creating an unmetered air leaking because the pcv sucks it into the intake and throws the air/fuel off.

But again i am not running a stock set-up because even the stock setup uses the theory of lets maintain a safe posotive crankcase pressure.

I am running a negative pressure set-up where the only fresh air per say is what comes past the rings. In essence i have every port on the engine plugged and i put vaccum from the intake post throttle plate into both the pcv and front freah air port to literally suck a vaccum on the crankcase.

I jist needed to know how much pressure was too much.
Think i have found what i needed to know from some drag racing forums though

 

[TBItoy]

Ok, after doing some looking around, the older 22re's (downward angle TB) had the pcv hose after the throttle blade. How the hell does that work? Doesn't seem like that would be able to create ANY PCV effect at all? Unless there is an internal passage in the intake manifold that plumbs it to the from tside fo the throttle blade. Has to be...

On newer 22RE's (like the 94 in my truck) it hooks up before the throttle blade on the throttle body, It doesn't create a un metered air leak because it is after the AFM.

I understand what you are trying to accomplish now from your last post, apparently I was missing something before. Not sure why you are wanting to do this? ie what the negative pressure is supposed to accomplish?


Everything on a 22re should be post AFM, I'll edit my previous post to make it more clear/correct.

 

[Rjhoward32006]

Thank you!!! Thats what i was going to show just hadnt had time to take pics as i have both engines at the house.
The one in my buggy is the old "85" model design. From my research it dosent work very well and could be the issue of why my newly rebuilt engine leaks oil from everywhere!!! I've rebuilt alot of these motors and this is the only one i've had issues with leaking alot of oil.

My main goal was just to make a simple negative pressure system to see if it helps with oil leakage/ seaping. To clean the hoses up a bit and to make it where it wouldnt hydro-lock.

But alot of people claim it helps makes more power and makes the engine last longer.
Less particles flying around inside, oil stays cleaner longer. Helps seal the rings better, etc...

On the old setup if you test that front clean air port it is not a vaccum port but a clean air port that has been metered by afm. If you "vent" this it creates an air leak and leans out the engine and the idle goes up

 

[gottagofast]

Fwiw pcv stands for positive crankcase ventilation...
It' only purpose is to burn hydrocarbons that otherwise would vent to atmosphere...

Since what you are trying to do has nothing to do with emissions I suggest you forget all about what the factory did and start from scratch...

Drawing manifold vacuum on a sealed crankcase to stop leaks is not likely a great idea... It might just start pulling dirt and water into your seals and crankcase.

I suggest that you plug everything off and set up a proper crankcase vent with a loop down low to keep the oil from pouring out when/if you flip

Once your crankcase is vented it should have no positive pressure... If it still leaks it's time to start replacing seals n gaskets.

 

[TBItoy]

Your pcv valve may just be faulty?

What/where is your engine leaking?

 

[Rjhoward32006]

Every seal that could ever leak. Is leaking all brand new seals.
Pcv was replaced then eliminated. Even ran breathers on the valve cover with no pcv and that made it even worse.

 

[gottagofast]

My gut says that if you have leaking seals and aren't pressurizing the crankcase then you have issues w the seals, the surfaces they run on or the installation of said seals...

I can't believe that the 22r or any other engine is special in this regard.