2001 S80 Intermittent oil light at speed

gargoyle · Post by **gargoyle** » 18 Mar 2014, 16:40

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 gauge.) Now they think it's a bad rod bearing. I can't imagine it would do that intermittently. 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

gargoyle · Post by **gargoyle** » 04 May 2014, 07:32

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?

Post by **Oly_850** » 16 May 2014, 16:35

How many miles on it? Bad main bearings will cause a flicker, but your pressure going to zero is frightening.

Have you replaced the sensor?

gargoyle · Post by **gargoyle** » 17 May 2014, 09:36

Been on vacation. 136000 miles. Using a gauge. 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

gargoyle · Post by **gargoyle** » 20 May 2014, 08:54

Cleaned the PVC box and no help. Could it be the cam adjuster?

benrk · Post by **benrk** » 20 May 2014, 10:31

Had similar issues with my 5cyl, it was sludged up, the po did an oil- sludge treatment @ SuperLube which apparently removed all the actual sludge but not the hardened crust which then disintegrated & settled in the oilpan as something looking like coffee grind, when I would punch & rev it I'd get a low oil pressure warning & it would flicker from thereon until the engine was shut off again for a while, my conclusion is that it sucked up the "coffee grind" at the high flow rate at high rpm & it would block the inlet screen, after sitting for 1/2hr or more it would be good again.
I've been trying from seafoam at idle before oilchange through LiquiMoly oil sludge treatment through filling the engine with kerosin over the weekend to driving with seafoam in the oil & in the end had shavings in the oil, wether it was from diluted oil not lubricating properly or coffee grind blocking an oil passage I don't know, but ultimately it destroyed the engine.
Short of opening top & bottom of the engine & physically removing the sludge & crust & replacing the entire PCV system I wouldn't consider any other method safe anymore, naturally, once you have the bottom open you should put an o-ring kit in if you haven't already done so.
I don't know much about the symptoms of failing bearings but if your PCV is sludged up you do have sludge issues that can cause your symptoms.

Good luck, Ben

gargoyle · Post by **gargoyle** » 20 May 2014, 11:57

Thanks Ben, Pan's been off and cleaned. Of course the dealer didn't clean the PCV when they had the pan off which my regular mechanic tells me is part of the standard procedure he's found in the manual. My regular guy is going to pull the pan and check it again as the pick up tube was not replaced either. Not going back to Tom Wood Volvo in Indianapolis again.