That was why your first comment confused me. If you’re pulling through one valve cover with vacuum, then you need metered makeup air available through the other. The orifice is just on the makeup air side of mine.

 

My driver side valve cover just has a small nipple, i.e. no PCV valve..
I understand now that I need a complete curciut. I did a bunch of research on this today. I am pretty sure I can not just attached a hose from the Driver side valve cover nipple to the manifold intake vacuum nipple without a PCV valve, it will run like it has a vacuum leak. Micheal, You get away not having a PCV valve because I think your cover has some sort of a PCV valve built into it. See pictures below with notes on them. Can anyone confirm my understanding?



So I am convinced I need a PCV valve, but based on my set up which is not stock which one should I get? It needs to open and close at the right transition points to work properly. I found an adjustable one made by M/E Wagner at:
http://mewagner.com/?p=444
It can be adjusted to your specific application, no guess work.
See the following link, a great explanation of the PCV system and how their valve works. Any one out there have tried it?
http://www.engineprofessional.com/ar...Q315_34-44.pdf
Soooooo... regardless of my oil leak I need a good PCV system and this adjustable PCV valve seems like the ticket. My plan forward is:
1. Order the DF-17 valve. $129, but 30-day money back trial.
2. Put it the line between the Driver side valve cover nipple and Intake manifold vacuum nipple
3. Drive around and see what happens. If oil leak stops awesome. If it does not I will still keep it because I need a good PCV system. Tear down the back of the engine to find the leak.
Any other suggestions let me know. If I don't hear from anyone I will report back after I complete steps 1-3.

 

Think I mentioned it 2 or 3 times above. No PCV valve on mine. An ORIFICE in the make up air valve cover nipple limits air flow so it doesn’t act like a vacuum leak. It’s why I encouraged you to inspect the connections on your valve covers. Orifice present = no need for pcv valve. No orifice = you need a pcv valve OR an orifice. Can always go this route for certainty -
http://www.eliteengineeringusa.com/ First class catch can/pcv set up.

 

I much appreciate the info, sorry if I am missing things. This is my first LS build and learning as I go..
Both valve covers have 3/8" nipples. How do I inspect if they have an orifice or not? Do I need to remove the covers and inspect from the inside? Obviously I haad the valve covers off for the rebuild, but honestly I don't remember what the inside looked like.

 

I think you're on the right path. If you don't have to pass emissions, then simply venting to atmosphere through some type of vented catch can is probably the easiest.

If you do have to pass emissions or just don't want to vent it to atmosphere then you need 1) some means of connecting the crankcase to the intake manifold; 2) some means of a trap to be sure the vacuum pull on the crankcase doesn't pull excessive oil out of the crankcase; 3) some means of metered make up air to the crankcase so that you don't pull a vacuum on the crankcase; and 4) some means of limiting make up air so that the whole system doesn't act like a vacuum leak. Your older set up is a bit different than mine - but I think you can figure out the components from there.

 

Yeah you don't need a PCV valve if your running that valley cover as it already has one built into it.

 

Thanks for confirming. I suspect the Driver side valve cover has the same type of thing inside. If I blow/suck on the a hose connected to the nipple there is some sort of restriction present. I will pull the valve cover this week to see what is inside, but do you know if this seem possible for a 2008 LS2 or LS3 valve cover?

 

PCV basics -- the path of airflow. Positive crankcase ventilation is an emissions control system. It's designed to pull the oil and unburned hydrocarbon laden vapors in the crankcase into the engine and combust them, rather than let them go straight to the atmosphere as they did on older cars. It does this by using manifold vacuum to create a bit of a "pull" on the crankcase thereby removing that nasty stuff into the intake so it can be burned by the engine.

Follow the path of the air. Metered air ENTERS the crankcase through the valve covers via that tube we have connected to the air intake tube. Its flow is limited on the later model cars by a tiny orifice inside that valve cover nipple -- this limits how much air can enter the engine. Because air is ENTERING the engine through the valve covers, there won't be any sort of oil trap there. It leaves the crankcase via the connection on the lifter valley -- which is connected to the intake manifold. Because the air leaving the crankcase through the valley might have oil vapor in it, there's usually some sort of trap there (lifter valley connection) to separate the oil and let it fall back into the crankcase. This limits the amount of oil that gets pulled into the intake -- which causes emissions problems and carbon deposits on the back of the intake valves. This was a problem area for the Gen 3 engines that was supposedly made better in the Gen 4 engines.

So -- any orifice limiting flow is gonna be on the valve cover fitting. Any trap separating oil is gonna be on the lifter valley fitting. That should be what you're looking for or looking to add if it's not there.

My motor was a Gen 4 OEM LS3 crate engine - same 430HP motor that came in C6 Corvettes from 08 to 13 or 14. It had the flow limiting orifices in the valve covers. Never took the manifold/lifter valley cover off -- don't know what's on the other side of that nipple -- but suspect some sort of oil trap is present.

 

OP if you cap off the driver side valve cover, run a line from the valley to the intake port and leave the passenger side as is you should be good to GO! I might run a sealed catch can between the line from the valley to the intake to catch any oil that may get past the built in PCV system on the valley cover.

 

The passenger side port that connects to a throttle body or bellow has just a line and no orifice or baffle. Since you don't have a PCV valley cover and your driver side valve cover has an orifice built into the line you should be able to run a 3/8" hose from the intake manifold port around to the driver side valve cover without the need for a PCV valve in the line. I can post up some pictures of a driver side valve cover that has an orifice if you like?

 

LS1 driver side valve cover

LS1 Passenger side

 

LS7 driver side

Notice the orifice.

LS7 passenger side

Notice how its baffled. Both LS7 valve covers are babbled this way.

 

SSTx, Michael thanks a ton for additional pictures and explanation. My valve covers are of the LS7 variety per the pictures. Based on this I will modify my "next steps list" and this weekend route the PCV system as SSTx mentions WITHOUT an external PCV valve and report back.

 

Following is what I did this weekend:

BEFORE MODIFICATION: Before I changed anything I put a vacuum gauge on the manifold driver side vacuum port, 15” of vacuum at idle with a set up I know did not have any vacuum leaks.
THE MODIFICATION: I connected the driver VC PCV port to the manifold passenger vacuum port (same size nipples). The passenger VC PCV port goes to my intake elbow (like before). I left the vacuum gauge on the manifold driver vacuum port. At idle 15” of vacuum. Whatever the restrictor is in the VC seems to work like a PCV valve. I know I was told this, but I wanted to see this with my own eyes. I cleaned up the block/block plate/scatter shield area underneath where the leak was.

I drove for about 10 miles. Nothing over 3500 RPM (remember only has 100 miles on the new motor). Parked, no oil drips. I rubbed my fingers over around the block/block plate/scatter shield area. There did seem to be an oil film. Possibly leftover residue from between the parts I could not clean and will just take more time to burn off… possible (hopefully). Regardless, for sure in the right direction. I will drive some more and see if the oil film burns off/goes away. If it does not in the next 50 miles or so I will then disassemble to inspect the rear cover and seal. It is possible I did damage to the seal with the lack of a proper PCV system. Another LS learning experience. Thanks for all the help. Once I know the leak is taken care of I will add a catch can to the system. With all the comments here and what I found researching PCV systems on LS engines it is the best way to go. Possible update later.