Intermittent low oil pressure

[Shiruba]

Hello, I am struggling with this problem and have officially run out of ideas. I have a 2000 v70 XC and I love this car. It started having low oil pressure problems and have replaced all the seals in the sump pan(they needed it). I have replaced the pcv system, and the oil pressure sensor.
The car will run fine for a bit then will periodically have the oil pressure light flicker periodically. It will sometimes just flicker other times it'll stay on for a few seconds then turn off. The odd thing is that it will also push the dipstick up a bit as well. Any ideas or advice would be greatly appreciated.

[scot850]

How many miles on your car?

The dipstick issue is one of 2 things. You have A) too much crank case pressure. Check with the latex/rubber glove over the oil filler with the
cap removed. Start or have someone start the engine and see if the glove inflates. If it
doesn't at idle, rev the engine and see if it then inflates. If it does the PCV system service
is needed. It could be clogged.
B) There is slight pressure in the crank case but the 2 'O' rings on the dipstick have shrunk
and hardened so cannot keep the dipstick in. New ones are NLA but P2 versions are the
same.

As for the oil pressure issue, it is either a very worn engine (hence first question) or a bad wire shorting somewhere or bad earth.

Neil.

[Shiruba]

Thanks for the quick reply Neil, the car has 209000 miles and the glove did not inflate it actually sucked in a tiny bit not sure if that's normal.

[Richard99]

A healthy PCV system should suck in, so it looks like you are good there. My guess would still be some issue with the sump but since you replaced all of the seals not sure. Next guess would be an electrical issue with the oil pressure sensor, as Neil suggested.

[Richard99]

I'm sure it's disappointing to have a light come on after doing the tedious sump seal replace. Hopefully you can get this sorted. Gotta keep these 98-00' V70XCs on the road!

[Shiruba]

What would be the best way to test the electrical for that sensor?

[scot850]

I would try checking the oil pressure sensor wire feeling it with your hand for breaks. Check also for corrosion at the sensor end of the wire.

Finally check all the engine grounds are intact. I think there are at least 4 around the engine bay. The main one to the bulkhead is one that can fail. But again check they are all clean.

Unfortunately, the next issue may be the oil pan seals are not good.

There is another weird issue I once had and a kind of 'out there' one. I had issues with oil pressure and funnily it was a 98 V70XC. What I eventually discovered was someone had replaced the dipstick and tube but used the wrong tube. It was shorter. So when I had the oil at the max line it was actually about a quart low.

If you have measured your oil back in when re-filling the engine this is not the issue. But is not, it may be worth removing the oil and measuring it back in. I think there is a wit and without oil filter quantity but don't know what it is. If you go that route, put a new filter on and and measure the oil back in. Check the level before starting and then start it and let it run for a short while, switch off and let the oil settle and check again. If the dipstick is good then then at least that is eliminated from the equation.

Neil.

[Shiruba]

Alright, I'll look into all that. Thank you for your informative posts. I sincerely hope it's not the seals in the pan I ordered those all genuine Volvo and it was a nightmare to do in my driveway. Hasn't driven 2000 miles since then.

[misha]

What oil viscosity you have in the engine?
What oil filter you installed?

If oil is too thin for the mileage and condition of the engine...oil pressure will not be adequate.

If oil filter is something aftermarket without built-in check valve....oil pressure will be compromised.

[erikv11]

Good points by misha.

Is there any evidence on the dipstick of foaming/aeration in the oil after a long drive? Would point to an issue with the seals.