Another place to look at for poor oil pressure is the camshaft retainer plate. When doing a camshaft swap some mechanics will reuse the old plate. If that orange gasket has been mashed flat it will dump the oil pressure from the oil galleys past that seal into the front cover resulting in poor oil pressure. I always replace that $20 dollar part doing a cam swap just for piece of mind. Not saying that's your issue... but you did replace that retainer plate didn't you?

 

Didn't know that could cause that, but yes this was replaced. I didn't reuse anything with a gasket, o-ring, or seal due to the mileage it had when I was doing the work. Except for the TB, I guess. Mechanic I took it to also checked over everything under the front cover and didn't notice anything amiss.

 

That orange gasket dose not come in the gasket kit and it's not replaceable... you have to replace the retainer plate itself.

You can't see anything "amiss" without removing that plate and running your finger over the gasket to see if the gasket still protrudes enough to make the seal.

 

Correct

Alright, when/if I tear it back down I will take another look at it to make sure it was sealing. The front cover will be the first thing to come off so Ill double check

 

Good to know you didn't overlook that important step

Most "mechanics" don't even inspect the plate they just slap it back on without knowing the consequences that small overlook can cause.

 

I didn't actually know it could cause an oil pressure issue, so learned something there, to me its just another 'seal' that Ive always swapped. Hell, as bad as everything looked that came off of this engine i was stoked to replace anything I could. Appreciate the input!

 

Welp, still insufficient oil pressure.

Let a diesel fuel and transmission fluid mixture sit in it and manually turned the engine over a few times over the weekend in hopes to knock some sludge loose. When I drained it i saw no debris in in, added new oil and filter, started it up and oil pressure jumped to 20psi idle right away (as my heart RACED), then steadily dropped back down to 4 once it warmed up a bit. Major blockage and or a bearing/tolerance failure. Sad day, but I have a local buyer for it already, and am stealing all of the fun parts off of it for another NBS project one day.

I know how cheap (by comparison) a swap would be, but I don't have the room/tooling/time to do it myself. With no spare car to drive in the meantime, and the lady fed up with it, we went out and bought a very nice used 2015 Yukon SLT. Hate to give up on this one - doesn't sit totally right with the mechanic in me - but its just how it went this time around. Best believe I'll be pulling a valve cover ASAP on the new Yukon to verify its been well cared for.

Change your oil and pay attention to what your rig is telling you, folks.