Loss of oil pressure…drain back? Topic is solved

[AccidentalWagonGuy]

Long time lurker…First time posting.

2005 V70 2.4 with almost 200,000 miles. Engine starts/runs great. Doesn’t really use oil. “Stop car no oil pressure” light came on. Installed a mechanical oil pressure gauge. Can idle at 30psi all day. Revs to 75psi after idling for any length of time.

However, if I drive 5 miles the pressure will drop to zero in about 20seconds. I park the car for a while and it will do the exact thing at the same place.

If I shut the car off and immediately restart it, it will have pressure for a few seconds before it starts dropping. If I let it sit for 10 seconds. It will have pressure for about 10-15 seconds. If I let it sit a minute, it will have pressure for about a minute. If it sets for a few minutes, I can drive 5 miles.

The pan has been pulled/cleaned out (had some crap in it). New o-rings in the tubes/sump (old o-rings looked good but brittle). New oil bleed valve thing in sump above the oil filter. Didn’t find cracks in the pick-up tube or tube that feeds oil cooler. Pick-up screen was pretty clean, now spotless.

The louvers under the oil fill cap is very gunky. Do you think the oil isn’t draining down into the sump quick enough? The square hole in the sump pan had a little something in it, but was nowhere near clogged. Maybe there’s gunk in the top end slowing the draining?? Is there anything prone to clog up or sludge-up that I could look at?

Any ideas? Doesn’t seem to be oil pump or piston cooling valve. I don’t know what else to consider. TIA

[Krons]

My 02 S60 2.4t had oring issues sucking air, I replaced the pressure sensor at the same time…likely didn’t need to but it was pretty gunked up.

[AccidentalWagonGuy]

That’s what I was hoping for! Put some new o-rings in it and it didn’t change anything. I’ve got a mechanical gauge installed, temporarily. Would be a good idea to put a new sensor in it when I take it out.