Oil pump failure

[OlDaz]

You seem to be running in circles in a way. No choice, you have to pull the pan - there's enough room to do it with the engine in the Jeep. One of the replies above mentioned a possible problem in the oil pickup and that would be my first check. I've seen the pickup fall off the tube, I've seen a hole worn in the tube where the pickup hinges, I once saw the tube gasket partially sucked into the tube to block area and I've seen the tube bolts left loose. The second suggestion that the rear main seal has collapsed (quite common with the modern replacements) is also a good one and you can check that while the pan is off. Only other suggestion is to make up a bolt on fitting to replace the pickup tube and pressurize the oil system so you can troubleshoot where the oil is going if none of the fore mentioned possibilities are the cause.

[OlDaz]

Currently into my CJ3B engine and just had another thought, you can partially check it with the pan off, although unfortunately you have to pull the engine to rectify. When the engine is stripped down there are pins in the block that locate in holes in the main bearings to stop them turning. These pins can fall out when the block is cleaned and if not replaced the main bearings can start to turn and eventually spin. I don't think this is your problem as the oil is fed to the gallery before it goes to the mains, so should register pressure at the gauge. If the engine has spun the mains, you will have excess clearance and lack of oil pressure.

[rcsteuer]

To all, thank you for the responses and apologies for the lack of follow-up.

So, what happened was this. After fighting with trying to figure out what happened, I dropped the oil pan and found metal shavings.  My jaw hit the ground.  I then pulled the crank and rod caps off - everything was scored. The crank had been resurfaced and rods were all reconditioned before putting this back together, so it wasn't fun to see the scoring.  I tore the rest of the engine down but didn't see much of anything to suggest where the metal shavings came from until I started cleaning the oil pickup.  The pickup was supposed to be NOS from DeBella Jeep Parts (the unit was in an original box).  However, as I started cleaning it, I saw particles from under the screen. I took the screen off and it was loaded with sandblast material.  So much for NOS!

It was obvious this wasn't a NOS part, but rather a part that someone, at some point, had simply sandblasted and stuck in a box.  When I contacted Pete, his response was "well sometimes that happens, and we have no way of knowing".  The crank needed to be resurfaced and new rod and crank bearings were installed (and, yes, Pete charged for the replacements!).

Since then, the Jeep (49 CJ3A) has been on the road and runs like a top.  I couldn't be happier with the eventual outcome.