Cummins N14 No oil pressure

I have a N14 Cummings engine. I suddenly lost oil pressure and the computer shut the engine down, assuming computer won't let it try to start because of the no oil pressure. .No rattles prior to it happening. I have replaced the oil pump with no results. Have tried manual pressure....no pressure on manual gauge. Any ideas? Pulled oil pan...clean..no filings or anything in oil pan. Things "appear" to look good inside engine. Engine was running fine...good oil pressure and then very next day on start up at 65 degrees outside temperature...oil pressure went to 35 psi where normally it was 45 psi on cold start and then continued to drop from start up until all lights came on...It is a Select plus engine...and then shut down...all happening within 3 minutes. Wont restart. has no oil pressure with manual gauge

 

New Oil pump and piston cooler nozzles are good.

 

There is a oil ...pressure bypass valve had a broken O ring and we put a new O ring on it.....However, there is NO oil pressure. Have a manual gauge hooked to the engine with NO pressure registering. Oil pan is off....nothing in the pan as far as filings or bearring material. The oil is going somewheres but trying to figure out where. Pump is pumping oil but back into the oil pan thru a hole somewheres. Which I had a diagram for how the oil runs thru the engine. Shop manual for this engine does not have one.

 

First of all....65 degrees OR less this time of year in Northern Maine!

Would it be possible to loose all oil pressure thru the turbo feed oil line? Turbo turns fine...looks good.

Have hooked an oil line and an 80/90 gear pump filled with 15/40 clean oil and have pumped directly into oil galley rifle with oil pan off...doesn't appear to be any oil coming out of anywhere in particular more than any where else...seems to be consistant....HOWEVER, have not taken the rocker covers off yet....