2004 H2 -220k
oil pressures has always been at 40psi
now about 10 on start and after a few miles down to 5. Higher rpms will increases to about 10 but then fall to almost 0 at idle. Only other symptom a very faint clicking and stutter or hesitation at idle. She runs fine up and down the Colorado passes - still has plenty of power.

Oil pressure reads within specs manually.
Trying to solve this - replaced O Ring, Replaced Sending Unit (no screen), replaced oil pump, replaced timing chain since I was there. No change in symptoms.
cleaned fuel injectors (2 had bad spray pattern), replaced nasty knok (spelling) sensor, new spark plus & wires. I had the shop check lifters - 2 different shops say they are fine. Of course I have changed the oil several times - no visible gunk or shiny stuff at the end of the drain.

so lots of work and I still have same symptoms. There is definitely something wrong - you can tell at idle. Throws no codes.

Any ideas on what I should try next?

 

You need to screw in a mechanical oil pressure gauge and get an accurate reading, your dash oil pressure gauge could be giving an erroneous reading.

 

My guess is unfortunately cam bearings......

Tim

 

If a scan tool is showing the pressure is correct then I'd assume some electrical connection or potentially the motors in the cluster are failing which is somewhat common.

 

Could be a cam bearing walked. When I pulled the cam on the lq4 I installed in my gbody, cam bearing #2 fell out. The cam wasn't damaged and neither was the block bore. I put new bearings in and was good to go.