oil relief valve info? 02 S60 2.4T

[jeffriehunter]

Have had oul pressure low light come on after engine had warmed and only at idle. So dropped pan for the 3rd time and removed the entire pcv system from air tube to oul trap and made sure.it is all perfect. Had the turbo rebuilt as well. Oil tube is sealed perfectly.

Here is my question........this time I removed the relief valve and decided to replace just because. Got the new one in today and you can blow through it in both directions? How does it actually work? Does the presence.of oil change how the valve works? I figured that it would be a valve that only opened under pressure.if the oil filter became clogged? I am just trying to learn......I am now a volvo pcv savant having removed and replaced this one three times now (we have also had some positive pressure). But found the turbo was malfunctioning so I also presume that if the turbo is not pulling air effectively then there is little vacuum produced in the air tube, thus creating no vacuum in the oil trap.

I am open to any and all insight on both topics and have been appreciative of the previous answers that helped me rework top to bottom correctly this time. Also replaced the oil pressure sensor this time. Have not yet finished the rebuild. Hoping to learn more an out this relief valve before I put the oil pan back on.

[DGM]

Apparently the little valve (29) is there to bleed air off the filter housing ( ie: after an oil change ).

The bypass valve in case of filter blockage that you mentioned is at the bottom of the filter cup (32).

The oil pipe that goes across the pan is often reported with broken seals (29a). It is known to leak and reduce pressure especially at idle.

Oil pan view .jpg (65.82 KiB) Viewed 5228 times

See this thread on the subject;

http://www.volvoforums.org.uk/showthrea ... 428&page=2

Hope this help,

[jeffriehunter]

What effect do you think it would have to replace 29 with a closed plug?

[DGM]

What effect do you think it would have to replace 29 with a closed plug?

The engine was engineered with this valve. Since you have a new one in your hands, personally I would replace it. My understanding is that it helps raise oil pressure at start up by bleeding air out of the filter housing cavity. " MisterT " had good hints to follow in the thread I attached. A mechanical gauge to measure oil pressure is a must to diagnose a problem like this. It removes the guessing of the service light.

See the following case studies on the subject;

http://atlanticmotorcar.com/volvo-s70-d ... p-pick-up/

http://www.atlanticmotorcar.me/case-stu ... -pressure/

One last thing. I haven't followed what you have done to your PCV but the clean-up of the circular shape unit attached under the intake manifold by a banjo bolt is "a must". It gets clog by sludge inside. If you have replaced the whole tube assembly then it is not an issue. If not it is definitely something to look at. Volvo has a service kit listed under the XC90 2.9 that can be adapted to replace this circular shape unit.