Volvo AWD 850 Forum

INDEX FOR 10/2025(CURRENT) INDEX FOR 6/2001 850 INDEX

[<<]  [>>]


THREADED THREADED EXPANDED FLAT PRINT ALL
MESSAGES IN THIS THREAD




  REPLY TO THIS MESSAGE    PRINT   SAVE 

850 low oil pressure after sitting for a while - Long Story but good! 850

posted by  someone claiming to be Ozzie on  Mon Apr 30 17:04 CST 2007 [RELATED]

This problem is driving me nuts, I just bought a 93 850 with 111k for my son and we are having one little problem.
Start the car in the morning and the oil light comes on. Stays on until engine speed is raised to over 1500 RPM for just a second or two then the light goes off. Drive the car for hours and never see the light come on. Let the car sit for a few hours and the problem comes back.
Trouble Shooting:
Removed the oil pressure switch and installed a gauge, start the engine cold and get about 5 to 8 psi. at idle, raise speed to 1500 RPM and the pressure climbs to about 80 psi. cold and as the engine heats up the pressure drops to about 25 psi. at idle and 80 psi. at 4000 RPM. Never drops below 20 psi no matter how hard you drive it. According to the book this appears within spec.
So I changed the oil and filter (Mann filter and Mobil 1 10w40)= same problem. Next removed a quart of oil added a quart of Gunk motor flush, ran 15 minutes drained oil, replaced with new oil and filter (Mann filter and Mobil 1 10w30)= same problem.
Next I dropped the pan and replaced the O rings on pickup tube and pan, genuine Volvo parts including the hot pink gasket liquid. The pan was really clean for 115k no sludge just the usual varnish and the tube was clear and clean, but I still scrubbed them out with solvent. New filter and oil again and for the first four startups cold, normal oil pressure 70 to 80 psi. cold - dropping to hot 25 psi. at idle. Appears the problem is SOLVED, but NO, next day problem returns, 5 to 8 psi. cold until the RPM is raised to over 1500.
Is the oil pump pressure relief valve sticking part way open, on at startup? I also noted a small thread in "valve" inside the sump right above the oil filter, I assume this valve functions to bleed off any air before it goes into the filter, please don't tell me this could be the problem. I really don't want to take off the pan again. If it is the pump oil pressure relief valve would I be better off ordering a new pump and be done with it or try to replace the relief valve and spring?
Just call me nuts with it.








  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    850 low oil pressure after sitting for a while - Long Story but good! 850

    posted by  someone claiming to be ksg on  Tue May 1 02:44 CST 2007 [RELATED]

    I seem to remember someone posted that the 93 had an oil level sensor as well as pressure sensor (dropped from later models). Is it possible you have this and it is setting the light? Is there something unusual about the circuit and logic of the sensors? We had a VW jetta with an oil pressure alarm that was tied somehow to the rpm of the engine - a very strange system that was unreliable and set the warning on at odd times.

    Also my owners book on a 95 says the oil light could flicker on at idle after hard driving - could 5-8 psi at idle be ok (admittedly I would never expect the pressure to be low at a cold start)? Is it possible your oil pressure sensor is a little off?

    I notice in my car at the very first start after changing the oil that the oil light stays on for a couple of seconds extra (though it does go out by itself). I usually drain the oil for about 10 min. I assumed this was normal. Maybe it has the same cause as your problem?








    •   REPLY TO THIS MESSAGE    PRINT   SAVE 

      850 low oil pressure after sitting for a while - Long Story but good! 850

      posted by  someone claiming to be Ozzie on  Wed May 2 16:13 CST 2007 [RELATED]

      Thanks for the reply, but the car does not have an oil level sensor only oil pressure lamp switch. As I noted I installed a oil pressure gauge and am using this to trouble shoot. The other symptom is after sitting overnight and starting the engine there is a lot of air in the oil as viewed through the oil filler cap. Something is causing the pump to get air bound and it won't pump oil into the block until the air is pushed out of the pump. The other thing I noted is the oil pressure fluctuates about 5 psi. at idle even though the base pressure may be 25 psi. hot.
      So air in the oil at startup, and a bouncing oil pressure. Still guessing it may be the oil pressure bypass valve if bypass oil vents directly back to the sump, or the mystery valve above the oil filter. I already changed out the oil pickup tube O ring and the tube itself looked crack free.








      •   REPLY TO THIS MESSAGE    PRINT   SAVE 

        850 low oil pressure after sitting for a while - Long Story but good! 850

        posted by  someone claiming to be Ozzie on  Sat May 5 18:10 CST 2007 [RELATED]

        Ah HA found the problem: SOLVED
        Removed the oil pump and found someone had replaced the gasket with the wrong one!
        There was a path from the pump inlet cavity to the center of the pump body. By this I mean where the crankshaft passes through the oil pump. There appears to be more than one pump and gasket available for the 850. Being paranoid I had picked up a oil pump at the dealer as well a gasket set for the pump before doing the work.
        The gasket that had been installed previously had a large opening in it at the pump inlet port (large D shape). The original pump has a small inlet port (crescent shape) and a slightly different back plate design. This allowed a gap of about 1/4" of space where the opening in the gasket did not cover a passage to the crankshaft clearance hole. This gap allowed a vacuum leak on the inlet side of the pump to the last main bearing area on the block. Which is why when the engine was started the low oil pressure, and once oil began to flow out of the last main bearing and fill the void the pressure would appear normal.
        The new style pump can use the large inlet port gasket but not vice versa. The old pump uses the old style gasket with a small crescent shaped inlet port.
        Now the oil pressure may be too high, over 100 psi. on a cold start and thats just at idle. Once the oil heats up a bit things settle out to about 95 psi. at 4k and 30 psi. at idle. Watch those gaskets EVEN FROM THE DEALER!







<< < > >>



©Jarrod Stenberg 1997-2022. All material except where indicated.


All participants agree to these terms.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. or Ford Motor Company. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.