97 detroit s60 12.7 problem after outframe rebuild

Hello. Posting for my father. Just had outframe done on motor. Took block to detroit they decked cleaned something about water jackets, etc. The only thing kept from old motor was crank, Injectors and oil pump assembly. Day after he noticed oil pressure was 40 cold when usually it would be close to 60 before rebuilt. Drove for 3 weeks, then last night when he went to start it the oil pressure light came on and shut off motor. He said it was not showing low but showing 0. Had it towed to freightliner because he was loaded with produce and detroit was too far away. They replaced sensor on side of motor I believe the sending unit for oil, or something similar to that. And they also replaced valve and or regulator. They said a piece had broken off of old regulator and piece of metal was in oil. Cranked it at dealership after replacing those parts and cleaning tube but still showing 0 doesn't move. Oil pump is on order but is 2 days out. My father all along assumed it was oil pump but being loaded he told them try the valve and if it didnt work would wait for oil pump to come in. They said they checked oil gauge and it is working. He is allready 900 into it for what they did today. Then Freightliner gave qte for 3500 for oil pump and checking replacing bearings. And saying all that needs to be done probally? When they crank it after test it runs and sounds fine but still shows 0, doesn't move. He wants to know what other people think or had this happen before. He thinks if it was something wrong with bearings or caps it should still have some pressure not just 0 but runs and sound good. I know this is long but I'm trying not to give full picture. Thanks for any info you have.

 

Thanks for the reply. I will tell him what you said. A local shop did the rebuild, he called detroit the day after rebuild they told him more than likely it was the oil regulator and or valve and they should've been replaced also. He just thought it wouldn't show 0 pressure if it were bearings .