HPOP reservoir leaks down?
I've been working on my dad's '95 7.3 because the HPOP reservoir leaks down after a couple days of sitting. So I replaced the o-rings in the HPOP and replaced the gasket between the HPOP and timing cover. And it still leaks down 6 or so inches.
I finally hooked up an oil pressure gauge in the port by the oil filter and tried to start the truck with the reservoir basically empty. Cranked it over for 20 seconds or so with no oil pressure registering on the gauge. Cranked it over again for 15 seconds or so and it fired up. Right before it started the oil pressure on the gauge started going up and once it was running it had about 50 psi of pressure.
But something I just realized today is that I'm pretty sure the HPOP didn't have a check valve in it even though the gasket that came off was the correct one for the HPOP with check valve.
So...can that check valve some how come out and disappear into the engine without it damaging anything? Or does it sound like the oil pump might be bad and allowing the oil to drain back?