Farmall h oil pressure gauge

The gage pressure not going down untill you crack the feed line open. Tells me the pressure is not bleeding down in the engine block after you stop, Or did somebody but a check valve in the feed line "check". Dirt or forren material in the feed line mite act like a check valve, But it's not likely. This could cause a proplem if your running the engine and the oil pressure drops due to low oil level,plugged filter or oil pump quits etc, And the gage stays up you will think oil pressure is good. And then hear the engine knocking.

Good luck and let us know

p.s. I'm not sure what you mean by "check" valve?

I don't know if somebody may have but one in your feed line.Cause there's no reason to have one in this line. Like I said before dirt or forren material in this line mite act like a check valve but not usually. Best bet is take the line and fittings off and try blowing air thru them in both directions. Some times fittings are made with a spring & ball check valve in them.The diesel fuel tank returns line on some of our diesels at home have a ball check fitting in them. This is so the fuel doesn't run back out of the tank when were changing fuel filters. Could be someone but one of these fittings in your oil feed line by mistake.

Other than that you have me stumped,Could be you just have a good tite motor. And like I said before, Doubble check the pressure reading on your gage with another one to see if you get the same readings.

Good luck again.