Help oil pressure

[Dmsooter]

Got a question hoping to pick someone's brain for a min? I have a 2011 Silverado 5.3 4x4 flex fuel 230k on the clock. Back earlier this year, it collapsed a lifter. Local auto parts only had a couple parts to complete the task. So I replaced 2 lifters (all they had) it was number 7 lifter. Replaced all the push rod for that side. Got everything back up and running everything seemed smooth running but my oil pressure was lower than usual. So went back in a few weeks later and replace the pick up tube gasket. Looked better but still not right. Replaced the oil pressure sensor and screen, Replaced all gaskets on everything I dug in to.....I got no oil leaks. I am just assuming I have a weak oil pump at this point. Truck will start up with 40-45 psi. Once it starts warming up it drops as low as 18-22 psi. Oil pump or am I leaning the wrong way?

[CamGTP]

A warm idle at 20psi is more than fine.

 

If your cruising pressure is 35-40psi and full throttle is 50ish, it's just fine.

[fustercluck]

there is a pressure relief valve for the afm located in the oil pan, if it sticks open you will loose approx 5-8psi oil pressure to the top of the engine..if you remove the oil filter you can use a long straight pick to unseat the valve and blow out debris.

if that doesnt change anything, take out the oil pressure switch and screen below it and check for debris..

if you have access to the oil filter adapter to install a pressure gauge there, that will tell you if the oil pump is producing enough pressure, thats actually where i start but thats usually a dealer only tool that i know of...should have at least 55psi from the pump

[Jworks]

Dmsooter, I have a 2011, 141k miles, same truck you have.  That happened to me also in the spring.  Running at hwy speed it was 21-22 psi.  Only when I raced the engine up did it go to 30.  Also, my check engine light came on signaling oil sensor.  I had it changed.  I got to 30psi hwy speed, 22 idle speed.  Another member of this forum said he'd had it years ago.  He changed oil & filter and all was good.  So, I tried that --- cheaper than hit & miss tries at a shop.  I changed oil & filter and Bingo.  At start up 42-45 or so.  After warming up hwy speed settles around 40, idle its at 30 (but sometimes goes to 21, which I do NOT understand).  Most of the time idle is 30psi though.  Bottom line:  when I changed o8il & new filter it all improved.  Why?  I don't have a clue.  My guess is something in the old filter, just a guess.