Iron 4.8/5.3 block bored to 5.7 with WS6Store rebuild kit/pistons/rings

Used 243 heads lightly decked

4.8 truck valley cover

4.8 truck DBW throttle body

truck valve covers with one vent port at rear of driver side and one at front of passenger side

LS1 intake


I had a line running from the forward facing passenger side valve cover port to the bung on the LS1 intake right behind the throttle body. I had a line on the driver side valve cover just to act as a vent, no PCV valve, just a straight piece of tubing.


This engine has only been started and run maybe 30 minutes total. It's starts right up and idles great. Currently it still has long tube headers fully open with no exhaust.


I noticed oil coming from the left side header, like a decent amount, barely any smoke. A/F ratio reads fine, O2 sensor is on the passenger side so all looks good on the Holley. Compression tested fine on all cylinders on the left bank. Leak down is just OK, but I did it on a cold engine and it really hasn't even seated the rings yet. First I checked the easy thing so saw valve seals look fine, they're all new.


I took the intake manifold off and that is when I found at least a pint of oil poured out of it. The intake ports on the driver side are all oily. The passenger side looks pretty clean but there was oil on both head surface when I took the manifold off. When the engine was running it was a little smokey, but given the amount of oil I found I would have expected it to be billowing blue smoke. The driver side plugs are black but not caked. Like I said this engine has only run for a short time. While I had initially suspected either a ring or valve seal problem I am now almost certain this is related to my cobbled together temporary "PCV" system. But it still seems like a lot of oil, and it seems almost totally concentrated to the driver side. I don't know what an LS1 manifold looks like inside but it is possible that I was somehow sucking in that much oil from the valve cover and sending it mostly to just the driver side of the intake?


My plan is to get an LS6 valley cover and I guess at this point run a catch can. I was prepared to start taking the engine apart to look for a ring issue until I found so much oil in the intake. Am I on the right track? I really don't want to take the car apart or pull the engine out before I understand what's going on fully and I know I am not fully understanding what these engines want for crankcase ventilation.

 

The problem was with the valve cover connected to the intake. The vacuum source on the intake should be connected to a baffled vent on the valley cover. The valve cover pipes should only be used for clean air going in, never for drawing crankcase fumes out.

 

Thank you, I feel like I've seen a million different PCV solutions on every LS forum I look at.

What I plan to do at this point is us a baffled catch can with one fitting drawing vacuum to the can from just behind the throttle body and the other port connected to the LS6 valley cover I have now ordered. I will use both valve covers for breathers to allow fresh air in. I'll have to figure out a way to either put filters on them or tie them in somewhere between the filter and throttle. If I use a catch can, do I still need a PCV valve in line from the vacuum source? The LS6 valley cover has an oil separator, does it have any sort of check valve?

One thing I guess I don't quite understand is on the catch cans with a breather on top, are they still able to make enough vacuum with that big filter letting air in that the crank case is under enough vacuum? And if a can with a breather still only has 2 hose fittings where does the fresh air go back into the engine? If one fitting draws vacuum to the can and the other pulls from the engine to the can, what purpose does the filter on top of the can serve? I just want to make sure I get the proper can that will accomplish what I am trying to do.

There are so many threads on blow by and PCV with these engines and millions of different answers to the same question. And a lot of inconsistency.

 

Had a adjustable pcv stick open on my engine thing looked like a old steam engine.
I’ve removed the pcv valve and just vent into a vented catch can now.