That's what I meant. Pulling thru the PCV.
Ok, here's what I did today. I don't normally go to NAPA because they are several miles out of my way but I did today. Turns out the guy who owns the local franchise is a Jeeper! He has a '73 CJ5. So we chatted. He said that it is not uncommon to have bad PCV's out of the box. He also said that NAPA has advised that a "rattling" PCV does not necessarily mean it's ok.
So, I used to own a '73 but mine was a V8 so I asked him about his which was a 4.2 also. He suggested I try a vented oil fill cap like his has. I put one on, plugged my PCV back into the grommet and took off. I drove about 10 miles, nothing off road or abusive, got back home and my engine is dry as a bone! I had driven it less than 5 miles before and it blew over 1 quart out the dip stick tube.
Turns out that he did not have a PCV for my engine in stock and ordered me one. I'll pick it up next time I'm over that way and I will install it as well.
I addressed each of your points below as well. Thanks!
I hope you interpreted it like I meant it. Not vacuum "to" the valve, but "through it." I think you did it right though.
That shows the valve is open and free - the only other possible thing a "defective" Valve could be is the orfice is too small - it can't handle the volume at speed. But even then, if should be evacuating the crankcase enough not to blow the oil out of the dipsick tube.<That is possilbe. I may have the wrong valve. I ordered a new one.>
It takes a goodly amount of pressure to force oil out the tube.<It blew over 1 quart out in less than 5 miles at less than 25 MPH.>
At idle, try holding your hand over the oil filler hole, you should not feel any pressure there - if anything, you should feel a little vacuum.< Small amount of vacuum>
And - in a dark room or night, shine a strong flashlight beam across the open oil filler hole. If it's "blowing out" you should see fumes coming out. If it's "sucking in" like it should you won't. Then try blowing a puff of cigarette smoke at it - it should pull it out of the air.
How does the engine run otherwise? Smooth at speed and at idle?
If you have a vacuum gauge handy, it may help to look at it. Notice the vacuum at idle AND most importantly whether the vacuum is stable - not fluctuating - "ticking". Make sure when you hook it up you use a very short hose. With a long hose the hose acts like a buffer and hides the "ticking."
Did you do anything else at the same time as changing the valve? Like removing the EGR valve, if any? <No>
Or tightening the manifold bolts? <No>
A compression test will probably show a very low cylinder. <That is what I'm afraid of! I will do it soon as I can borrow one.>
Has it overheated recently? <No>
Also check for exhaust in the water, I'm wondering if exhaust is getting back into the crankcase at speed somehow (like a cracked head or head gasket,) pressurizing it more than the PCV can handle. <Water looks fine. No bubbles like a compression leak into the cooling system>
What really is the mystery is WHY it was coincidental with the PCV Valve change. Dumb luck?
<My thoughts exactly! WHY?
I feel sure it is an issue with the particular PCV I have. Wrong one, defective, etc.>