I searched as much as I can and I am just a little lost. I am hoping you guys can point me in the right direction.

I have a 2000 Cherokee Classic. 173,xxx miles. We have replaced quite a bit of parts; starter, radiator, hoses, water pump, thermostat, power steering. In the engine we have done lifters (had a decent tick when I bought it and thought it would be a good place to start), valve cover gasket, head gasket, crankshaft and bearing ( a matched set), as well as many other things that I cannot think of at the moment.

We did the internal stuff because we had low oil pressure on the gauge on the dash. Replaced the oil pressure sensor and nothing changed; put on a mechanical gauge and it verified the dash reading of 5 PSI when warm. There was some sludge buildup in the pick up line at the oil pump, so we replaced the oil pump and cleaned the block. I was told the block got steamed BUT did not get a chemical dip. It was obvious that the crank bearings were deprived of lubrication. Once all of this was put back together, we are having similar problems - the pressure is still down around 5 PSI.

We are about to pull it back apart and check the oil pump and pick up tube for more sludge, but the pan and motor was cleaned really well.

Anything else I should look at while it is apart? Some local mechanics have said "cam bearings" and piston rings. We did test the pistons prior to tear down and we had 135 PSI.
Thanks for any help. This is starting to get deeper than my knowledge can allow.

 

2000-2001 XJs have head cracking issues with the 0331 head casting. Your description sounds like you've possibly run with coolant contaminated oil that wiped your crank bearings, and thus lost oil pressure.

 

it sounds like you did a halfass engine rebuild hoping to fix an issue without any diagnosis. the piston rings won’t affect oil pressure.

thrust bearing tolerance? how much play?
any damage to the crank? typically bearing damage goes both ways
cam bearing inspection? did anyone look at the cam bearings?
standard crank bearing set? no +/- .010 ?
was trash circulated in the engine before disassembly?
you plastigage the new crank and bearings?