Cadillac Repair: Oil Pressure, cadillac seville, low oil pressure

Question
I have replaced the oil pump in this 86 Cadillac Seville 4.1LG that were not pumping when i bought it, after looking at the repair manual it shows a different looking one than currently install.
 Are there a different between the seville and the Deville and if so what is it and what else could cause it not to deliver oil to the lifters.  

Answer
Hi Jimmy, I'm not sure if the pumps were different and would have to call a parts store. I know the RWD is different than the Seville or Deville. Over the years the pumps could change design so I wouldn't let that be a concern. Now on to the oil problem. When you put the pump in did you install an o-ring on the pump tube where it mounts to the block? And there was an oil pump driveshaft that came out with the pump? It would be good to know oil pressure by hooking up a gage, then you would have an idea what is happening pressurewise. Worn bearings will cause low oil pressure. One time I had one apart and found a camshaft bearing so worn that oil pressure was about 4psi with a new pump installed. Cadillac doesn't recommend installing new cam bearings, all 5 are a different size, but to replace the engine instead. Maybe something is plugging an oil galley in the crankshaft or block. If there arn't any external leaks then the problem has to be internal. Let me know how it goes. Bill