Oil Pressure at idle

Does anyone know why I would have oil pressure (20psi) at idle warm-up (1500rpm)& zero pressure once engine is at normal operating temp?

Thanks, any ideas would be appreciated  
.
Dirty Deeds DunderJeep 77 CJ5 304

My proublem with normal pressure (cold)loss of pressure after warm-up was from worn cam bearing's,I did everything else encluding oil pump!  

yup worn bearing or bad sensor.  

you can go to a 20w50 too see if it helps up the presure. its not a cure but may prolong a rebuild. typically you want 10LBS of PSI  for every 1k RPMs  
02 Tj with a few mods

thx  
.
Dirty Deeds DunderJeep 77 CJ5 304

thx, I'll try 20-50 a new filter and a sensor if needed  
.
Dirty Deeds DunderJeep 77 CJ5 304

Changed out the filter, added some 20-50 along with some stabilizer, checked the pump and bypass. It still reads around 40 while warming-up @1500 rpm, however, once warm I was able to maintain 10 to 12 psi at 1500 rpm, so there was some improvement. I just recently installed a DUI HEI and think I might retard the advance just a touch, from 12 btdc down to maybe 10  & see if that helps the situation. Ya know it seems that a number of different little problems have come up since I installed the new distributor. Plugs, Oil Pressure, Runs a little Hotter, and the voltage gauge jumps around every once in awhile. Thanks, the DunderJeep project continues.  
.
Dirty Deeds DunderJeep 77 CJ5 304

I think I was able to fix the oil pressure problem. I retarded the HEI from 12 to about 9 deg btdc and cleaned out he cooling system. The engine at normal operating temp now runs between 180 & 200. These two changes seemed to have stabilized the oil pressure to 10 psi per 1000 rpm.  
.
Dirty Deeds DunderJeep 77 CJ5 304

Running 20-50 will only get you by for a little while longer. If you're not willing to do a complete rebuild, just pull it apart and do all the bearings, or at least do the rods and mains if you dont want to pull the upper end. But if the rod and main bearings dont show heavy wear you should do the cam bearings too. While you're in there you might as well do the oil pump, even though its not likely to be the problem.  

Thx, but this is a little beyond my capbilities, very bad back, & no space large enough to work in. I've been wanting to find a good local mechanic to do a valve job as well. Any idea what your suggestion should cost? Ballpark range?  
.
Dirty Deeds DunderJeep 77 CJ5 304

Generally the oil pressure is dictated by your main bearing clearance on the crankshaft.  If the bearings get walered out you will lose oil pressure, it is not difficult to change them, you can do it in your drive way just pull the oil pan and then the main caps and replace them one at a time.  The bearings run anywhere from $20-$100 depending on what kind you get.  A shop will charge you a couple hundred dollars to do the repair.  Hope this helps ya.  

yes it does, thx very much  
.
Dirty Deeds DunderJeep 77 CJ5 304