It was rebuilt only because it had over 300,000 miles on it and the main bearings for warn

 

Was the motor bearing clearance at least checked with plasti gauge?

 

A 2003 PCV valve will not have a plunger that shakes inside of it so if you used one that does, that's the wrong one. The one you took out was a fixed orifice valve which is correct for its build year.

 

It had good clearance

 

There are multiple issues... the lack of oil pressure and oil consumption are not related. If the rings didn't seal, bad valve guides or seals, or the PCV system was pulling oil into the intake you should still have normal oil pressure. Loss of oil pressure never leads to a oil consumption issue and pressure bleed off just dumps oil back to the pan not into the combustion chamber.

 

The line connecting the PVC system was messed up just found that so I replaced it that may take care of the problem with the oil in the intake but my main concern is the low oil pressure I can't figure out where I'm losing pressure

 

I was told that that was the wrong one for it but thank you I will get another one and try the hollow one

 

the hollow one is notorious for sucking oil into the intake

 

Hate to say it but it sounds like the motor needs to be pulled down, inspected, at minimum hone the cylinders but they likely need more than a hone since it has over 300k.

The 155 psi on one cylinder vs 185 on all others could be poor ring seal or poor valve sealing. Were the valves at least lapped in? Checked while the motor was down?

The oil could be blow by from poor ring seal which I would suspect it would have with only new rings put into 300k mile cylinders. Pistons may also have some wear and rock too much too.

Did y'all check the main bearing clearance? Replace cam bearings? Bearing clearance is generally responsible for oil pressure, as long as it's not being lost through the barbell or cam plate.

GM oil sending units are notorious for failing as well, you may try a new one first just to see if that helps the oil pressure.

What about valve seals? Were those replaced?

And when you did the compression test... did you inspect the plugs? Did any of them have excessive oil on them? If so suspect that cylinder for poor ring seal or valve guide or seal.

 

0 - 5 psi at idle and it's still running? Maybe you have a bad oil pressure sender, or gauge issue? Might be time to hook a mechanical oil pressure gauge to it to verify what's really going on there.