Hi
@7amannnyy, first of all welcome! As
@OR VietVet stated first suspect is sender or sender screen. Remove and while you're there do yourself a favor and attach a mechanical oil pressure gauge, and report back here with the results.
I am skeptical of it being a sender itself due to the fact you stated you get an engine/valve train tick when the pressure is low. That
inclines me to believe that the reading may be accurate, and the pressure is a bit low. Could still be that screen restricting flow though. Check there first.
If the mechanical gauge shows low, next step I would do is drop the oil pan and see how that pickup tube o-ring looks, as well as cleaning any crap out from the pickup tube screen itself. If the truck is a 2wd pan removal is much easier, 4wd requires dropping the front differential off the mounts and lowering it a few inches for pan clearance. Can send a good video if needed.
A test you can do before you pull the pan and start looking at the o-ring condition, is overfill the engine with around 2 quarts extra of oil. Raise the rear end of the vehicle up pretty high and run the engine at IDLE(don't risk damage by revving the snot out of it while overfilled). If pressure returns to normal, get ready to replace that pickup o-ring. Basically by overfilling it you're ensuring the oil level is over the level of that o-ring. It'll be submerged in oil, which will temporarily seal it and stop a worn o-ring from sucking up air.
The thing is, removing the pickup tube o-ring is basically half the job of replacing the oil pump. If you felt inclined, you could continue to removing the front accessories and removing the front cover to replace the oil pump. May not be necessary, but not a terrible idea at your mileage/kms. However, if the pickup o-ring isn't the problem, and it was the oil pump, you'd have to tear the pan back out, basically redoing the work you already did plus some. The prerogative is yours. On my 2002 Suburban I replaced just the pickup o-ring and pressure is still lower than ideal, although it did go up some(around 28psi at idle), the oil pump may be bad but my bearings may also be just about smoked as well. I can say I continued to run the engine for a couple of weeks before doing the o-ring job, and I have earned myself a permanent lifter tick on the intake side of cylinder 4, so try to get this sorted out ASAP, before you're looking at minimum of cam and lifter job in the future like me.
Hope this helps guide you as to the most common possibilities, of course there's the chance that the issue is none of the above, and the engine has worn bearings or something, but I'm a positive thinker. As long as maintenance has been kept up with that's highly unlikely at your mileage!
