68corvette

My car was drive 120 000km once I bought it so decided to clean up the intake and EGR based on forum recommendations.
No problems there.
Parts cleaned pretty nicely using soda blasting and ultrasonic cleaner.




Also it was nice to notice that runner injection is keeping the valve area clean.



One week later I got CEL light about engine running lean.

During cleanup I washed the PCV valve well and noticed that it remained constantly open as its installed horizontally.
The spring pressure / spring is not long enough to push the valve completely shut.
Typically PCV valves are mounted vertically, so the weight of the valve keeps it closed during acceleration
I thought that maby the spring in PCV is dead, or maby I just assembled some gasket incorrectly and decided to replace the PCV when intake had to be anyways removed.

When I disassembled the intake manifold, I was a bit suprised about the amount of oil in intake manifold, there was several spoons of oil in intake manifold plenum and it was really oily all the way up to head runners, which I had just cleaned.



When comparing to a new valve, they were identical and new had similar spring than the old one, keeping the valve open constantly.


As I had two valves and catch can is not an option for me in cold climate, I decided to modify the old valve so that its keeping PCV valve closed when there is not pressure differential.
There is a "washer" and the end of the pcv is pressed to hold the washer.
I just grind the pressd part away and washer and internal parts came out nicely.


I extended the spring carefully, testing and fitting and streching and testing, untill it kept the PCV valve in closed position.
Then I just hammered the washers side for a shrink fit, tried to push it out to verify that it stays there.


So now it will just work at higher vacuum conditions and not sucking the oil in all the time.
I tried to measure the required vacuum when valve starts to open, but the needed vacuum was quite a small and valv is leaking a bit as its not really air tight, so I could not get exact pressure differential measured.

Autumn is approching, so I need to monitor the sludge build up and oil color to verify sufficient crank case ventilation.
I will also at some point take out TB again to see if there is less oil collected.

Not saying I did right or wrong and can not recommend this to anyone, just wanted to raise some thought and possibly discussion =)

Sorry about big pictures, I do not know how to attach thumbnails.