v70xc oil pressure drop

saltydog · Post by **saltydog** » 21 Aug 2005, 20:56

here's one....01 xcountry with 62,000 mi, well serviced running synthetic. oil pressure warning appears intermittantly after car has been running for several hours.only at low idle - 6-700rpm. not all the time. not consistant with any condition. some days appears at every traffic light, some times can go for days without seeing it. always goes out when rpm bumped slightly & will disappear for several minutes if car is shut off & immeadiately restarted. 2 dealers stumped....flame box just replaced, engine flushed 2 new sensors - pan has been dropped and some goop cleaned from pick up, but not bad. Any ideas? I'm desperate and leaving the keys in the ignition when I park but so far, no luck.

turbotim2 · Post by **turbotim2** » 22 Aug 2005, 11:02

Are you losing any oil at all? What is the weight of the oil you are using? What part of the country are you in (i.e. very hot)? This could be a number of different things but the first thing that comes to mind is the oil pressure sensor or oil pump.

saltydog · Post by **saltydog** » 22 Aug 2005, 12:37

running 5w50 Mobile 1....I'm in Toronto the problem started at Chrismas when it was 0 & this summer has averaged around 90, so it's not weather related. I've replaced the sending unit twice - odds against 3 bad ones ???? if it was oil pump, problem would be consistant either occurring all the time or when the oil loses viscosity when hot (which synthetic isn't supposed to do). Like I said, I can go for a week & not see this thing - pull off the highway after a 2 hour cruise & not see it but be in traffic & have it stare at me. Anyone know how sturdy these turbo seals are? If I had a REAL oil starvation problem, I gotta believe my turbo should have yaked by now. I hear about electrical nightmares in these things, thoughts on a bad brain?

Guest · Post by **Guest** » 22 Aug 2005, 12:52

OK, so you have ruled out a few. When the light comes on it doesn't leave a code in memory? Does it ever happen when you just fire it up and let it warm up, say in winter? It sounds like the oil pressure may be just at the very limits of when it will trip the light. I would tend to think mechanical before electrical but I am no expert.

Guest · Post by **Guest** » 22 Aug 2005, 13:33

NEVER when first started in fact, car has to run at operating temp for several hours before symptoms appear, that's what so frustrating - there's no rhyme or reason. If it's throwing a code other than low oil pressure I haven't been told. There's something in the oil galleys that's obstructing. I know that my old T-5 had a check valve in the filter to keep it from bleeding off when idle. The new style uses a canister - is there a check valve inside this motor to perform the same task? I want my 850 back.

turbotim2 · Post by **turbotim2** » 23 Aug 2005, 05:50

OK, so if it doesn't do it at cold start up that would indicate that you are lsoing viscosity as it warms up. I know the synthetic is not supposed to do that, but temperature will make a difference to any fluid. I don't know if there is a bleed back check valve in there or not but I would tend to doubt it, and this shouldn't effect your oil pressure when running. I personnally don't use synthetic oils, but is there a next heavier weight grade that you can try?

saltydog · Post by **saltydog** » 23 Aug 2005, 06:15

well, I could put straight 90 weight in there but that doesn't exactly have a great flow rate for here...the problem with playing with different weights is the turbo - this would be easily (easier) solved if I didn't need to be concerned about feeding the turbo. Heavier oil might keep the light off, but may not be enough to keep from blowing it & that's an expensive test. I'm leaning towards weak oil pump even though it doesn't display all the usual traits....no idea how tough that one is but I can't even get a quote on a long block - nobody's done one yet. BTW, switching to the synthetic made a big difference in frequency - a lot less.

acito616 · Post by **acito616** » 23 Aug 2005, 09:55

I would T in a mechanical oil pressure guage to see the actual pressure when the light comes on this should answer all your questions.
JM

Jot · Post by **Jot** » 23 Aug 2005, 11:46

6-700 RPM sounds low I thought idle was 8-850.

saltydog · Post by **saltydog** » 23 Aug 2005, 12:16

that's definately the next step. The oil pump is an impeller type design that may have internal damage. there seems to be a feeling that the previous owner (I got the car with 15,000 mi) put duralube or some other similar crap in it, & I've basically got hardening of the arteries & the vanes in the pump may be partially clogged. enough there to push oil just over the pressure limit but not enogh once things get hot & expand. This should be a warning to anyone thinking about those "amazing" additives.