Pcv *clean side*
Thread Starter
TECH Senior Member
Joined: Jan 2004
Posts: 5,798
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From: St.Charles MO
Pcv *clean side* So there are hundreds of threads discussing the PCV dirty side, however my issue is with the clean side right now. I have a catch can on the dirty side that is working, but im getting oil through the clean side (valve cover to throttle body). Ive read that this could be from excessive crank pressure, however my dipstick has never blown out or anything. Ive also read that during WOT the PCV system dirty and clean side "cancel" each other out sort of speak because of the extra vacuum from the intake (vs just at idle or cruising).
Regardless Im getting oil from that side and looking at options to stop it.
Id like to have a potential "fix" rather than just running a catch can on that side and catch the oil, although I will if i have to.
Ive seen RX has a "clean side seperator" https://www.rxperformanceproducts.co...ide-separator/
However if this issue is from excessive crankcase pressure I could see oil potentially getting past this.
Which leads me to the breather cap with a one-way check valve
https://www.rxperformanceproducts.co...-oil-fill-cap/
(I want a closed system, I do not want to have unmetered air getting in, I would have this with a "one way valve out" in it so no air gets in, but excessive crank pressure would be released and in theory oil wouldn't be pushed up the clean line then).
Anyone have experience or advice with this?
Also, I wont run an "open" system with everything capped off and open breathers on the valve covers, from what Ive seen that smells terrible and doesn't keep the engine clean like a proper PVC system.
Regardless Im getting oil from that side and looking at options to stop it.
Id like to have a potential "fix" rather than just running a catch can on that side and catch the oil, although I will if i have to.
Ive seen RX has a "clean side seperator" https://www.rxperformanceproducts.co...ide-separator/
However if this issue is from excessive crankcase pressure I could see oil potentially getting past this.
Which leads me to the breather cap with a one-way check valve
https://www.rxperformanceproducts.co...-oil-fill-cap/
(I want a closed system, I do not want to have unmetered air getting in, I would have this with a "one way valve out" in it so no air gets in, but excessive crank pressure would be released and in theory oil wouldn't be pushed up the clean line then).
Anyone have experience or advice with this?
Also, I wont run an "open" system with everything capped off and open breathers on the valve covers, from what Ive seen that smells terrible and doesn't keep the engine clean like a proper PVC system.
Thread Starter
TECH Senior Member
Joined: Jan 2004
Posts: 5,798
Likes: 16
From: St.Charles MO
I have the GM PCV valve that came with the LS6 valley cover I ordered, it would only have around ~5000 miles on it and it still rattles when I shake it so I would assume that it works fine (looks and rattles just like the factory one that was on the car).
I put a sump style plastic fuel filter in the inlet side to
act as a catch can.
With any inlet restriction at all, at WOT you end up with
lower pressure before the throttle blade than in the
crankcase and the oil fog will blow out the inlet path,
leaving you a snail track on the TB wall and a greasy
intake. This path is unmetered.
I haven't caught much oil, but I also seldom have
conditions for sustained WOT operation and not much
blowby as far as I can tell.
act as a catch can.
With any inlet restriction at all, at WOT you end up with
lower pressure before the throttle blade than in the
crankcase and the oil fog will blow out the inlet path,
leaving you a snail track on the TB wall and a greasy
intake. This path is unmetered.
I haven't caught much oil, but I also seldom have
conditions for sustained WOT operation and not much
blowby as far as I can tell.
I'd go with the RX breather w/1-way valve, that should stop you from getting any oil up at the TB. You'll probably notice a slight crankcase oil smell when the valve opens momentarily, but not any oily mess.
That's my observation over around the last year with run a (DIY)breather w/1-way valve setup, with my GM performance cast passenger side valve-cover. The only reason I don't run the RX breather is because the fill hole on my PS valve cover doesn't except a factory style twist lock fill cap, only push-in style.
That's my observation over around the last year with run a (DIY)breather w/1-way valve setup, with my GM performance cast passenger side valve-cover. The only reason I don't run the RX breather is because the fill hole on my PS valve cover doesn't except a factory style twist lock fill cap, only push-in style.
Thread Starter
TECH Senior Member
Joined: Jan 2004
Posts: 5,798
Likes: 16
From: St.Charles MO
I'd go with the RX breather w/1-way valve, that should stop you from getting any oil up at the TB. You'll probably notice a slight crankcase oil smell when the valve opens momentarily, but not any oily mess.
That's my observation over around the last year with run a (DIY)breather w/1-way valve setup, with my GM performance cast passenger side valve-cover. The only reason I don't run the RX breather is because the fill hole on my PS valve cover doesn't except a factory style twist lock fill cap, only push-in style.
That's my observation over around the last year with run a (DIY)breather w/1-way valve setup, with my GM performance cast passenger side valve-cover. The only reason I don't run the RX breather is because the fill hole on my PS valve cover doesn't except a factory style twist lock fill cap, only push-in style.
You getting any oil in your intake with your setup?
Are you running a one way out check valve?
And you still have the stock hose setup from the valve cover to your throttle body?
This is kinda what I was thinking, I just wanted to see if any one had tried it and had success.
You getting any oil in your intake with your setup?
Are you running a one way out check valve?
And you still have the stock hose setup from the valve cover to your throttle body?
You getting any oil in your intake with your setup?
Are you running a one way out check valve?
And you still have the stock hose setup from the valve cover to your throttle body?
Don't laugh, my 1 way CV is a modified air injection valve I took off my Z28 yrs ago, it actually works really good, but it's a little bulky.
Yes, I still use the TB side port for a fresh air source, but I run a -AN T-fitting off it then into -AN fittings I installed in both valve covers for a fresh air since I'm running a +04 LS6 valley cover. I also get no oil at the TB at all with my no baffle valve covers, before the CV I used to get small amount of oil residue back up at the TB between oil changes.
