Pcv system removal due to crank case pressure

davec73

SCCoA Member
I am thinking about removing my pcv system and installing crank case breathers on the valve covers. I have an oil catch system now and it catches some of the oil from the crank case but my motor still blows oil out of the oil cap (aftermarket not completely sealed) and the dipstick tube. I have also noticed I am still getting some oil in the supercharger and IC tubes. Is it a good ideal to do this and how will affect the way my car runs? I don't car about emmisions or a little oil smell from the breathers and I know they will fit. This will eliminate a lot of vacuum line for me and if it wont hurt anything performance or dependability wise I think it would be the way for me to go but I havnt seen a lot of guys do this so that's why I am asking.
 
I have also noticed I am still getting some oil in the supercharger and IC tubes. .

Seems to be a normal...

Any idea why you'd be tossing oil elsewhere, tho? That doesn't sound normal, and it might be worthwhile to understand why, rather than just venting via breathers, I think.

I'd also think the reason you don't see breathers in use, so much, is because blowing oil out like that isn't a common situation...? I'd try to find out why the crankcase is being over-pressurized (?) and fix that instead of just accommodating what may be a mechanical issue.
 
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Seems to be a normal...

Any idea why you'd be tossing oil elsewhere, tho? That doesn't sound normal, and it might be worthwhile to understand why, rather than just venting via breathers, I think.

I'd also think the reason you don't see breathers in use, so much, is because blowing oil out like that isn't a common situation...? I'd try to find out why the crankcase is being over-pressurized (?) and fix that instead of just accommodating what may be a mechanical issue.

Its a new motor with 18 + psi of boost could an aftermarket pcv cause it to do this?
 
New as in not broken in and the rings haven't seated yet?

I'm not sure all PCVs are created equal. If you can blow thru yours easily, it's not seating under boost at all. I went through 4 before I found one (motor craft black plastic) that would seat at all...be sure to test at an angle similar to how it sits on the valve cover...).
 
New as in not broken in and the rings haven't seated yet?

I'm not sure all PCVs are created equal. If you can blow thru yours easily, it's not seating under boost at all. I went through 4 before I found one (motor craft black plastic) that would seat at all...be sure to test at an angle similar to how it sits on the valve cover...).
Motor has around 700 miles on it now. It seems to be leveling off to where it isn't blowing it out of the dipstick and oil cap as bad but it will still do it under high boost pressure. I havnt hammered on it too much because I have been driving it on the 93 tune without methanol. Back to my original question though what would it hurt to vent straight at the valve cover through breathers and remove the pcv system all together? I am just trying to simplify things a bit and let my motor breath better to free up power and prevent the supercharger from getting oil in it.
 
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Your fuel trims may be a little off after you put the breathers on , but it shouldn't hurt anything. Be ready for an oily mess, but I guess you already have that.

What I like to do is get the biggest ID fittings you can to put in the valve covers and route both cover outlets to the inlet of the blower that way you get a vacuum in the lines to help evacuate the crankcase. But you need catch cans on both covers so you don't get oil in the intake. Which the oil in the intake is probably coming from the driver side line that you don't have the catch can on.
 
Your fuel trims may be a little off after you put the breathers on , but it shouldn't hurt anything. Be ready for an oily mess, but I guess you already have that.

What I like to do is get the biggest ID fittings you can to put in the valve covers and route both cover outlets to the inlet of the blower that way you get a vacuum in the lines to help evacuate the crankcase. But you need catch cans on both covers so you don't get oil in the intake. Which the oil in the intake is probably coming from the driver side line that you don't have the catch can on.

There is little to no oil coming out of the driver side into the intake, the intake tube and inlet plenum are clean up to the point where the vacuum line comes into the back. All or most of the oil (which isn't a lot, a little oil makes a big mess lol) is coming from the passenger side through the pcv valve vacuum line portion. I did like you said and increased the size of the fittings and vacuum lines to the catch can and it helped some but under heavy boos it still spray a little oil out of the valve cover and dipstick tube. I was just thinking if I got rid of it all together it would free up a bunch of space and remove a part of the system that has a huge potential for vacuum leaks.
 
What systems do the turbo guys use. maybe that could be one answer. afterall boost is boost wether turbo or blower.
 
What systems do the turbo guys use. maybe that could be one answer. afterall boost is boost wether turbo or blower.

On the old blue 95 "Merry Christmas" Turbo car I used to have I just had breathers in the valve covers. I had to wrap them with wrist sweat bands and cut a hole in a tuna can so as to fit underneath of them to catch the oil when racing. I had plans to run a vacuum evacuation system through a catch can but that car was sold. I was trying to find a picture of the setup, but I can't find one.

** edit - I guess I will also add that that car made 28psi. The oil never came out through the dipstick and that motor only had 1500 miles on it.
 
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New as in not broken in and the rings haven't seated yet?


You know, that is a good thought I think...

*Warning, hypothesis below - may be totally wrong....*

I wonder if the ring-seating break-in procedure doesn't have something to do with these PCV-like problems, when the PCV checks out okay. Also, I would imagine, the type/material of rings you use.

Venting the pressure will be a metered-air loss, no matter how you delete it, which is why Chris mentioned the fuel trims being a little off. If you have a QH and do your own tuning, and check it every so often, in my mind, it would be okay. However, I don't know how much air we are talking....if you go from less blow-by to more blow-by, your AFR would get richer (not sure how much). If you go from more blow-by to less, your AFR would go leaner. For your guys case, where you have new engines, which possibly may not have rings fully seated, perhaps you would be putting yourself at risk - when the rings fully seat.

One of the SC engine builders around here could comment with some intelligence....
 
Dave,

Please double check your vacuum hose plumbing and make sure that the hose which connects to the PCV valve on the passenger side valve cover and the fuel vapor canister purge solenoid is attached to the Inlet plenum (that only sees vacuum) and not the return plenum that sees vacuum and boost.

You should also check your PCV valve to insure it is allowing air to travel out of the motor, but not back in. It's just a plastic nipple with a check valve. The connection on the drivers side cover is just a breather that allows air to enter the motor to replace whatever air is removed through the PCV valve.

It will run fine with the PCV valve disconnected and using breathers on the valve cover or better yet running a pair of hoses from the rocker covers to a remote mounted catch can that is vented, like I have on my 93 SC with the turbocharged v8. Downside is the unpleasant smell and small amount of smoke or steam, especially in winter when running the heater because of where the air inlet vents are located.

David
 
It made me feel better about my build that davec73s Dalke built motor does the same thing.. why?? Still not sure! Matt you got to witness the phenomenon when we were road tunning my car! I'll never forget the alarmed look on you're face when the burnt oil smell hit lol mine ONLY blows by the dipstick tube still debating a "Race Only" catch system off the dipstick tube. Ice' rubber hose and a oil can plus some zip ties.
 
It made me feel better about my build that davec73s Dalke built motor does the same thing.. why?? Still not sure! Matt you got to witness the phenomenon when we were road tunning my car! I'll never forget the alarmed look on you're face when the burnt oil smell hit lol mine ONLY blows by the dipstick tube still debating a "Race Only" catch system off the dipstick tube. Ice' rubber hose and a oil can plus some zip ties.

Or just put a rubber vacuum cap and a small hose clamp on the dipstick tube like I do on my turbo car.

http://www.autozone.com/autozone/ac...acuum-cap/_/N-25v0?itemIdentifier=439195_0_0_

David
 
Fancy new oil pans have locking dipsticks. ;)

Not sure why you guys have the blowby under boost, but recommend backing off the tune until it stops doing that. If the rings haven't seated and you beat on the thing too much you'll just ruin the rings. Recommend leak down tests when you have a chance. No sense beating things to death.
 
Fancy new oil pans have locking dipsticks. ;)

Not sure why you guys have the blowby under boost, but recommend backing off the tune until it stops doing that. If the rings haven't seated and you beat on the thing too much you'll just ruin the rings. Recommend leak down tests when you have a chance. No sense beating things to death.

Mine has 5/6k on it now its probably about as broke in as it can get I assume
 
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