Low oil pressure?

If you are holding 45psi at start up, then the bearing in the engine are still good. My concern is the ticking you get. That sounds like a lifter when the pressure gets too low. If you can, now that you have a new filter and oil, I would like you to use the mechanical pressure gauge again. If it read 23PSI on the mechanical one, that is good. Have you tried replacing the oil sending unit?

Here is something to think about. When metal gets hot, it expands. Because of that, the pressure should increase when it warms up and not drop. At this point, I feel you either have a bad sending unit or the pick up tube screen on the oil pump is partially plugged. The ticking has me concerned, but if really had 0 psi of pressure, you would hear rod and bearing knock too.

Check it out with the mechanical gauge, and you may want to replace the sending unit. It is a cheap part and easy to replace.

Let me know what you find.

Joe
PS: When you change the oil, always replace the filter too. With the detergent in the oil, basically it cleans the old filter and takes the dirt throughout the engine.

Let me put it to you this way, my 94 chevy pick up with about 250k miles on runs at about 15psi hot and it has been that way for the last 100k that I can remember. Gm says that as long as you have above 6 psi and there are no obvious engine problems that you are fine and I agree. Hope this helps ease your mind.

There are two plugs that can cause this they both deal with the main oil galley and are at the rear under the main bearing cap and behind a plug from the rear. You can use a ball bearing for the plug under main as that is what was done in later years. Also do not use a crappy oil filter I only recommend napa, Purolator, bosch wix and ac is ok. Also test the pressure with a manual gauge prior to look for problems.

Yes sometimes they fall out or are loose but check with a manual gauge prior to do ing that as the gauge in tuck may be off.