Very low oil pressure, pump or O-rings
 

New to the forum, hello. I was driving my sisters 95 850 turbo and accelerted from a stop sign, and about 1 minute later the oil light came on. I wanted to get it home which was a few miles and by the time i got home it was just starting to tick and groan a little.

So we pulled the oil light sender and replaced it with a mechanicaloil pressure guage and these are the results.
When completley cold at start up oil pressure = 78 psi
It slowly decreased
After 2 minutes after cold start up = 65 psi
Then we revved it just a bit and it made the pressure drop at a faster rate
After about 4 minutes = 30 PSI
AFter about 6 minutes = 20 PSI
After about 8-10 minutes = 10 psi
After 12 minutes the temp gauge was centered and oil pressure was about 3 psi.

Reving the engine does nothing to affect the oil pressure, it stays at about 3 psi all the time.
Would this be the oil pump itself, or can the oil pan o-rings cause this. THank you.

RE: Very low oil pressure, pump or O-rings
 

The oil pumps usually don't go bad but it is possible it is bad. Usually if it is the O-rings it would be lower pressure all the time.

Just wanted to let people know that doing the O-ring job restored all oil pressure and the thing runs better and quieter than it ever did. The oil pan was covered with caked on sludge and the pickup strainer was almost completley clogged. There is also a square vertical channel (about 1" square) that is towards the center of the pan that has a corresponding passage way into the bottom of the engine block. Both passage ways on the block and in the oil pan were completely packed solid with dired up sludge. It was so difficult to clean the pan we just picked up another one. The most interesting thing about this job was that all of the O-rings looked in very good condition. I am assuming that the lack of oil pressure was due to a clogged oil strainer and passage ways more than blown o-rings.

Interesting do you know what the previous history of the car was? Oil changes every X thousand miles? Kinda of oil?

Also how hard is it to hook up an oil pressure gauge? And what gauge did you use? Inexpensive? I kinda want to do that before dropping the pan on my car to see if I even need to.