Hi everyone, new to the forum, but a 10yr volvo lover.
I just got a great deal on a 2002 V70 XC. On the way home the "no oil pressure" light and warning came on after accidentally running it to 7000rpms (I didn't figure out the manual shift yet.) . I shut the car off and ran it again quite a few miles with no warning. It came on again, and went out after shutting the car off. Everything is running fine, no noises. I put a gauge on it and I have plenty of pressure but maybe too much? When bringing it up to 4000rpms, it will go up to 80p.si. Should it release before then? Could I have a bad release valve? Or do I just need to replace the sensor? Is it strange that the light doesn't come on when the sensor is unplugged?
Thanks for the help!
Jason

 

I drove it around today and tried to reproduce the conditions. It was running great with nice pressure. After 20 mins, I decided to push the the rpms. After a few tries, I lost pressure. I stopped and started again, which only brought me back up to 30psi. I let it sit 15 mins and everything is normal again. Could this be the oil pickup tube sludge or o-ring problem? Or is this the pressure release valve?
Thanks for your help!

 

Lots of members have this problem - including me on TWO cars.

As everybody suggests I have had the sump off, cleaned all the crud out and replaced rge two O rings, oil pickup seal and the two seals on the pipe between the oil filter housing and oil coller.

Still the ?>??**xxx same on both cars. I have seen a post suggesting the air bleed valve on top of the oil filter housing could be at fault.

Sumps will now come off again - I think I'll fit wing - nuts !!

Just got my sump off AGAIN while thinking and fildling I polished the pipe that connects the oil filter body to the oil cooler with wire wool and it looks as though it is cracked. Tried blowing through it but can't get it to leak - may be different when hot and under more pressure.

Volvo will sell me one as part of a new sump!!!

I will get it weled / brazed

 

I cleaned the sump, but haven't quite finished the job. There was a square passage way running from the bottom of the sump up into the block. It was solidly clogged. It would be great if that was the problem. Everything else seemed fine. I had my torque wrench set for 17 instead of 13 foot pounds and stripped 2 bolts. I hope it doesn't leak now.

 

I believe that square hole is just the oil return drain from the top of the engine and has no effect on the oil pressure, was 100% blocked on both my V70's top and bottom halves.

I have discovered that the pickup mesh was blocked on one of my engines after I had re-assembled it and ran for half an hour. It looked clean first time - but I suspect that the design of the pickup head holds "crud" that is allowed to drop off the mesh when the engine has beed turned off and suction released. There is a trough in the pickup head that collects anthing that drops off the screen.

I sloshed mine around in petrol and all sorts of rubbish came out.

This seems to have solved my problem

 

I cleaned that out, but still the same problem. The fact that the pressure can get very high and then drop makes me think it could be a high pressure release valve. Is it on the oil pump or separate somehow?

 

It is within the pump, and I don't think replacement parts are available.

There is a little air bleed valve on top of the oil filter housing within the sump which opens to allow trapped air to be bled out of the system that should be closed by the oil pressure.

There is a post suggesting this may become jammed open. I found that blowing through this (by mouth) does not close it, but an airline does.

 

Just out of curiosity - you didn't buy a Clarke torque wrench did you?

I thought I had cleaned that pickup pipe first time, but had the same symptoms as you good pressure until run for a while then it dropped rapidly (especialy if reved fast)

If I stopped the engine and restarted the pressure came back.

When I had the sump off again I found dirt in the pickup.

I assume the oil pressure sucked the crud onto the mesh, and when the engine was shut down it dropped off again.

 

I shook what seemed like sand out of the pick up. It was all stuck around the lip of the pick-up tube. I suppose that some more junk could find it's way in there again even though I cleaned it.

I was thinking I might pull the oil pump to see if the spring on the relief valve is faulty, or maybe the gate is all sludged up?

 

I did search this and other forums for members that had cured low oil pressure by cleaning the relief valve or replacing the whole pump but didn't find any.

I am about to take the sump off my 1999 V70 to see if I missed anything. It did have a cracked pipe which I had repaired, but it was worse after I put it all back together.

I am about to insure my 2001 V70 to see if I have repaired that one.

V70's do seem to be prone to low oil pressure don't they?

 

Did you ever figure this out? I am having oil pressure problems and looking for ideas.