Quote:
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.
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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.