My 2001 S80 (2.9) oil pressure light started coming on at speed, not while idling. Turn the car off for 5 minutes and it may come back on after driving 4-5 minutes and it may not. The dealer fixed the oil pickup tube and it seemed OK. Now it's doing it again after 300 miles. They checked it again, and it took some time for them to get to a low pressure state (using a gage.) Now they think it's a bad rod bearing. I can't imagine it would do that intermttently. Maybe once the engine warmed up and every time, but not 300 miles later and occasionally. I'm wondering about clogged oil return lines or a malfunctioning oil pressure relief valve. Any ideas? Thanks

 

My mechanic replaced the oil pump and the bypass valve. Thought maybe the valve was bad as I've read they can crack. He ran it then when he kicked it down at about 3500 it lost pressure.
Went to almost 0. Turned it off and it got back some pressure, but not to normal. Let it sit and it regains pressure again until you get to about 3500 again. Any ideas?

 

How is your pcv system?

 

No idea. Can that kill the oil pressure? Hadn't thought it could, but I'm not a mechanic.

 

Trust me I didn't think it could either. We had a couple of cars come in that needed pcv cleanings so we did them, afterwards the cars came back with low oil pressure lights with symptoms exactly like yours. We replaced everything and performed numerous oil flushes to the cars and it kept happening. Eventually we decided to plug the pcv system even though everyone including Volvo said it would not do anything. With the pcv system plugged again the vehicle never lost oil pressure ever again.

 

When the pcv clogs, it causes sludge inside the oil pan. from there, it can burst a rod bearing, or can clog the oil pick up tube. Did you had the oil pan removed for inspection? Removing the pan also gives access to clean pcv drain holes inside the pan.

 

Trust me oragex. We inspected and replace everything that had to do with oil pressure. Plus im pretty sure sure the sludge issue had been fixed with the 10-15 oil flushes that were done to the engine.I understand your thinking but you also have to think of it this way, there was no oil pressure problems before the pcv cleaning with a clogged pcv. Then after the pcv cleaning that's when the oil pressure problems started to happen.

 

Been on vacation. the PVC box or whatever it's call was filled with sludge. Waiting on a seal that got damaged during removal to try again. The pan was removed and the pick up tube cleaned originally. waiting for the seal to see if cleaning the box helps. the pressure was 90 psi till the engine hit 3500 rpm. Pressure fell like a rock. Turn it off and restart and got a little pressure back. WAit a while and it gets pressure back till you hit 3500 again and then you have zero. Thanks again

 

You mean, the oil pressure drops to 0 above 3500 rpm? The o-rings seals inside the oil pan were replaced/inspected?

 

yes, oil pan cleaned and the pickup tube cleaned and new orings installed.

 

Looks like I had a private message, but I can't open it.

 

Have you tried reposing the oil pump

 

Replaced the oil pump.

 

Just an idea, the oil pressure sensor might have an issue?

 

My mechanic is using a guage. Thanks,

 

Could it be the cam adjuster?

 

Cam adjuster?