oil pressure warning- theory or solved?

[wsconner]

I was able to get an oil pressure gauge and install it temporarily on the 3GM30F. I definitely have oil pressure, but it was interesting to see the results. I enclosed some vid links in case anyone was interested in hearing/seeing these results. At 2500 rpm immediately after start up the pressure bounced between 40-50 psi.
https://youtu.be/Ym6CBjTXG0Q

At 3000 rpms after 15 min run time, the pressure held steady at 62 psi.
https://youtu.be/vy_7_X626Yo

When backing down throttle to ~800 rpm the pressure bounced around at 20 psi.
https://youtu.be/PPxDKUXHUL8

According to the yanmar service manual, pressure at idle should be 7.2 psi and at 3,500 rpm should be 42-57 psi. Not sure what the results actually mean, but I at least know there is pressure and have some form of baseline measurements to assess.

[Thumbs Up]

It is nice to have a gauge and an idiot light/buzzer. But the idiot light is way more important. If you have a sudden drop in pressure for some reason you will never notice it in time to shut the engine off with just the gauge. Your oil pressure typically is what it is. Knowing the exact psi is not going to help you. There is nothing that you can do to change or adjust it. You either have enough or you don't. If you don't, you need to shut your motor down within seconds to avoid damage. You would never notice it in time with just a gauge!

[a64pilot]

Two sides to every story, I think a gauge is vital, reason is you learn what is normal, and if normal changes, you investigate it. With an idiot light or buzzer you once choice is immediate shutdown, without knowing if its a wire, or a sensor fault, of it it’s for real.
With a gauge when your idiot warning goes off, first thing you do is look at the gauge to confirm or deny if it’s real.

[a64pilot]

Originally Posted by wsconner

I was able to get an oil pressure gauge and install it temporarily on the 3GM30F. I definitely have oil pressure, but it was interesting to see the results. I enclosed some vid links in case anyone was interested in hearing/seeing these results. At 2500 rpm immediately after start up the pressure bounced between 40-50 psi.
https://youtu.be/Ym6CBjTXG0Q

At 3000 rpms after 15 min run time, the pressure held steady at 62 psi.
https://youtu.be/vy_7_X626Yo

When backing down throttle to ~800 rpm the pressure bounced around at 20 psi.
https://youtu.be/PPxDKUXHUL8

According to the yanmar service manual, pressure at idle should be 7.2 psi and at 3,500 rpm should be 42-57 psi. Not sure what the results actually mean, but I at least know there is pressure and have some form of baseline measurements to assess.

You likely found out that your oil pressure relief valve is set to about 62 PSI and that oil pressure wise, you have a healthy engine.

Now as far as pressures being above what the Manual says, that is not a bad thing, however it’s possible that the Manual assume oil at operating temperatures, and maybe when you were looking the oil wasn’t fully up to temp, as a general rule the colder the oil, the higher the pressure, and the hotter, the lower.

That 7.2 PSI is a minimum I’m sure, not what it should be, but a number that if it’s not at least that, that you need to find out why.