300 tdi oil pressure problems

Good evening,
New to these sites. We have 2 discos with 300 tdis. ! never misses a beat, my sons blew its turbo and ran on its own oil Ouch. Seized up!

I sources a block that had a standard crank and good bores. Honed, re rung with new B/ Ends and Mains. New oil pump rotas and pressure relief assembly. The rear plate to the pump was not marked and it went together well.

It ran well for 100 miles but has now developed low oil pressure when hot. Ive put a new temp sensor for the oil cooler in, new pressure switch and changed the oil pressure relief vale in but the light comes on when warm?? I dropped a main cap and a big end cap off when I checked the oil pressure relief valve and they were fine.

I'm about to take the timing cover and oil pump assembly off but am wondering, could it be a cam shaft bush come loose. I would rather check this but is it more likely to be tags on he inside of the oil pump rota and the flat faces on the crank shaft having failed.

This seems like the never ending story and I could d with some good suggestions. Please help. Stew the screw

did you refit or knock oil squirts ,oil feed for head come off no1 cam bearing and the rest or one bably worn or loose would cause low pressuure

Wow, thanks for that! Was hoping for a message before X mas.
I took the under piston jets out when I had the cylinders honed. Put them back and torqued them up but the were difficult to get in with my big hands. Dis heartened because I thought 300 tdis were stronger than ours have been. Would you advise me taking injection pump and breather, and vacuum pump off and inspecting them before doing the oil pump.
Thank you for this
stew the screw

P.S Checked the cam lobes when I was inspecting the block and they seemed fine. I didn't remove the cam shaft but hind sight is an exact science lol.

they are good but its previous lack of servicing lets them down ,apart from unforeseen turbo problems etc, would be worth seeing if bearings have moved, pick up pipe sealed well on casing ,relief valve ,oil squirt hasnt bust off

Your right. I don't know the previous history of the donor block. Are the oil feed holes on the camshaft bushes aligned with an oil feed in the block for the cam shaft bushes or do the bushes have a reservoir / rebate in the block around the circumference on the bushes to provide oil regardless of the bushes alignment?
I worked on Cummins diesels and they needed the holes aligning before being slide hammered in. If they have moved, can they be knocked back in and locktighted or is it a strip down (again).
I am confident the oil pump rotas are fine. Just kicking myself that Ive put the head on but might have to remove it to remove the cam followers