'87 4.0 Low oil Pressure after warm up...

[xjfish]

Upon startup of my '87 Renix the oil pressure guage will read about 50psi or so then it seems to slowly and steadily drop after driving. After around 15 min or so it will read just above 0, About 5-10psi or so? (but always seem to have some pressure) It does leak a little oil from just about everywhere, maybe a few drips on the ground after sitting for a day. I've never had to add oil in between changes. Fresh oil change with (probably kinda light) 10-30. Purolator Oil filter. Somewhat noisy lifters. Idles fine and starts easy and haven't noticed any recent power loss... Is this bad and something that needs to be addressed right away? Any suggestions?

Thanks for reading.

 

[JJacobs]

Verify your readings with a mechanical gauge. Worn engine bearings cause a big drop in oil pressure, and your lifters are a good indicator of that.

 

[8Mud]

The wifes 87 had kind of low oil pressure, I checked it against a mechanical gauge and the oil pressure sender or gauge was lieing a bit to the low side.
I only checked the rear mains, at the last rear crank seal change and found the main bearing was about at the outside allowable tolernace, made me think all of the lower bearings were problably loose and loosing some pressure. The oil pump tested OK for clearances. The screen was gummed up a bit.
I started using 20-50 synthetic (for diesel motors) and the pressure came up some and didn´t fall off as much. Figured the motor was loose enough, the heavy oil wasn´t going to hurt much.
Just as a side note (on my 88), I just replaced my valve cover gasket and having a bit of free time (and being a bit compulsive) I plugged the oil return holes in the head (with pieces of paper towel) and cleaned the top end pretty good with a screwdriver, some brake cleaner and a shop vac. The top end quieted down noticeably and my oil pressure fell just a touch. Makes me think the gunk was messing with the flow some.