Oil pressure warning light coming on and off, 1996 850

[abscate]

The crankcase air pressure is really independent of the liquid oil pressure, these things aren’t related

[eleaf]

Just did the oil pressure test
Cold Idle: 75 psi
Hot Idle: 45 psi
3000 rpm: 78 psi


Seems high? Didn't dip down low at all...

Cleaned out the pcv flame trap (one of the holes to a tiny vacuum hose was clogged). But it is still blowing up the glove when I place it over the oil filler hole and pushing air/smoke out of the dipstick tube when I raise it.
Is this oil pressure concerning? What may be going on here...?

[sleddriver]

Re: Pcv system. When I replaced the factory system, I found all was well except for the two hard plastic lines that run from the turbo intake to "the box". Both were cracked in half resulting in no engine vacuum pulling vapor to be combusted.

FF a few years after replacing it all with factory parts and the large rigid plastic line had already cracked!! Right under the distributer. I fixed it with silicone vac. tubing. Obviously your NA will be different.

I think you have two unrelated issues. Never had to deal with oil light, oil pump, etc. so no experience to offer. I'd just be guessing.....

I have used BG109 engine flush with great results on two occasions.

[eleaf]

I redid the oil pressure test and I think I didn't let the oil heat up all the way, as here are the updated readings I got.

cold idle: 75psi
HOT idle: 20 psi
HOT 3000rpm: 65psi
Seems more normal eh?

I'm swapping the oil pressure switch and hoping some silicone tape around the wiring harness that passes nearby it will take care of the oil pressure light issue as the mechanical guage did not dip below 20 psi after running for a bit.

I took apart the visible pcv hoses (the one on top of engine near valve cover, and the two lines connecting to the flame trap. I blew into each line while closing one of the other three and was able to determine the airflow is clear going through all the tubes except for the thin little hose that connects from the flame trap to the oil trap. When I blew in that tiny hose, I didn't feel any air coming out of the other tubes, I feel like I could hear a little bit of air coming out under the intake manifold, but not entirely sure... Maybe the rubber elbow is going out near the oil trap connection to the small hose? The air easily blew through the other tubes making me think the oil trap box is clear/clean. Should blowing into the small hard plastic tube that connects to the flame trap create air pressure through one of the other hoses?

I'm a little intimidated with taking the intake manifold off... Debating whether to take it to the indy mechanic or ripping off the intake would be worth it... Anyone know where the small line from the flame trap connects too... into the oil trap or somewhere else..? From looking at pictures I think it connects to the left side of the intake manifold. Possibly accessible without the intake manifold removed?

[eleaf]

Update:
I was able to remove the small pcv hose. It connects to the underside left of the intake manifold, goes under the IM and connects to the pcv flame trap. I was able to disconnect it on both sides without removing the intake manifold and snake it out. Looks like the small hose is good, no leaks.

However, I did notice that the flame trap has a potential air leak spot where it connects to the air intake where the o-ring connects. I assume this should be a closed system and air shouldn't be allowed to escape here? Seems like the connection doesn't snap down air-tight. Also looked like oil was leaking out at this point in the past below the flame trap onto the engine.. I went ahead and connected the flame trap to the air intake and spread a bunch of silicone around the o-ring and around the connection as a temporary test in an attempt to create an air-tight seal. I will see if this is the issue once it cures a bit.

[eleaf]

Well, sealing the connection between the flame trap and and the air intake didn't do it. Smoke still coming out of the dipstick/pressure pushing a little oil out of oil filler cap.

Should it instantly clear up or does it have to drive for a few quite a bit?

[erikv11]

It should clear up right away.

Are you able to plug the hoses and blow bubbles into the oil pan sump? If not, the bottom drain port is clogged. Apologies if you already confirmed that passage is open.

Might be time for a compression test.

Small line from the flame trap connects to the nipple on the passenger side of the intake manifold. Hard to reach but you can do it with long nose pliers. viewtopic.php?t=65002

[eleaf]

Alright, feel like I'm getting closer...
Wondering if it would be worth pouring some seafoam down the pcv hose that connects from valve cover down to the oil trap to clear any junk if the bottom port is clogged? And then change the oil soon after...
I don't recall being able to blow 'bubbles' through the oil. I would plug the hose connecting to the flame trap, then blow through the top pcv hose that connects under the valve cover while also plugging the port that is under the valve cover yes? I'm thinking I tried that but couldn't blow through when the hole under the valve cover was closed. Air did easily blow through each hose and out the top valve cover port when I left it open, but it didn't make an oil bubbling sound. Would this indicate clogged lower oil trap port to the oil sump?

Also wondering if it's worth using thicker diameter 5/16th inch vacuum hose from the intake manifold to the flame trap, the little one is hard plastic and seems like it may impede airflow a bit.

[eleaf]

An update!
I replaced the oil pressure switch and added a new layer of plastic wire loom around the wires that pass over the pressure switch.
Went for a long drive, no oil pressure light warning, so I think that fixed it!

PCV system: replaced flame trap and the air intake plastic that connects (where the air from the filter comes through and the flame trap screws into - the old one was worn where the flame trap screws into causing it to not seal correctly). I also capped the vacuum line that goes to the air box thermostat and capped the three vacuum lines on the airbox (this airbox is modded for cold air intake only), it had the airbox vacuum hoses all connected before but realize there may have been a slight vacuum leak where the airbox thermostat usually sits (was removed)...

Anyways, now when I do the glove test over the oil cap, it does not blow the glove up! Instead it sucks the fingers together and pulls in slightly. I'm no longer seeing an oil leak at the oil filler cap so it's better than it was.
When I remove the oil dipstick, I don't see smoke blowing out anymore at idle, but if I rev it up a bit, I do see a little smoke coming out of the dipstick. Is this normal??

[jtp]

Awesome work on the PCV job. Going from positive to negative pressure at idle is insanely good for the long term health of the engine and your bank account.

I wouldn’t stress the smoke under load too much. As these engines age is it’s becoming normal. I’m one who thinks the PCV system needs a bit more capacity like cn90 added when he enlarged the main hose on his system.

That’s all details though compared to the massive improvements you made by swapping out the old hoses.