Help!!!

Hi all

anyone had this problem?

I have a twin engine searay
with 454's


I just hand the heads , valve's, new rocker arms, and valve springs
done in the one engine

I ran the boat at the dock for a good 8 house with no issues. I even
changed the oil several times just to be sure


I took the boat out last night and after running under load for about
15 minutes the engine in question started to lose oil pressure.

At once I shut the motor down.

I got back to the dock expecting to see oil sprayed all over my engine
compartment, but I found nothing, no leaks drips or any sigh of oil
leakage

Checked the dip stick and it was fill and very clean.

well I got back to my slip and took a look at the oil filer , it
seemed to have some stuff in it as I assumed that it would, so I
changed it, and re started the motor.

As the filter filled the oil pressure gauge jumped up, but not as high
as it should.


Anyone got any thoughts ?

on why all of a sudden I got no oil pressure?

Thanks
M