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.
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.
Wednesday, February 17th, 2010 AT 9:45 AM