HossinatorSS

iTrader: (1)

Background: Had my car since new, now has 120k miles on it. Usually cold idle oil pressure is just under 50 and drops to just over 40 when warm and ~60 at WOT. I changed the oil in April (less than 300 miles ago) and had the car parked in the garage for 2 months.

I recently fired it up and was blowing oil out of intake and exhaust side of rear turbo (puddle in garage at exhaust outlet). The smoke increased with rpm. Turbo has been on for 50k/8 years and no oil problems at all. I've checked the scavenge pump and check-valve, they're good. The last resort was an oil restrictor before a turbo rebuild. It did the trick at least at idle and revving in neutral. I haven't taken it for a spin yet. However, I noticed that now, at cold idle, my oil pressure is at 60 psi and rises from there with rpm (again revving in neutral). I ran the car long enough for it to get warm but not full operating temp and oil psi dropped to maybe 55 at idle. Looking back, this would explain why the turbo was oozing oil at idle without the restrictor.

I would think sending unit/gauge but the turbo is displaying physical signs of high pressure too. Can anyone think of a reason the oil pressure would be higher all of a sudden after sitting for two months?

Thanks in advance for any help!

silverz28camaro

iTrader: (20)

How did you test the pump? When my turbo oozed it was from a poor drainback angle. I have gravity return)

Is your oil pump stock? or aftermarket? Maybe the pressure releif valve in the pump got stuck?? just a thought....I would think its either your return pump or your oil pumps relief valve

silverz28camaro

iTrader: (20)

Also what type of oil do you use? weight and brand type

HossinatorSS

iTrader: (1)

I tested the scavenge pump by comparing the amount it pumped, at idle, compared to the turbo draining straight into a bucket (gravity) over the same amount of time. Both situations had the same oil output and no impact on oil pass-by. In fact the turbo had nearly the same oil output with the restrictor installed. That could be because without it the excess was oozing out the intake/exhaust.

My oil pump is stock and I use AC Delco filters (PF 46 I think) with mobil1 5w-30. Have done that since before it hit 10k miles.

I've heard stories of the relief valve getting stuck open and dropping psi to 0 but can it get stuck in a closed position and cause a rise in oil pressure?

#AngryTransAm

Change the oil filter only and crank it up and see what you get, it's a cheap test to do. 300 miles ain't much but what kind of miles are they? Track miles where your hot oil sits to cook itself when the car is off and not circulating the oil between track sessions could thicken up the oil, but I am guessing this is not the case.

Wild card, extra crank pressure via turbo contribution (pushing or restricting).

Would be interesting to see if your getting a lot of blowby and if the turbo and its system internals were messing with pressure.

Fab you up a crank case pressure gauge, could hook a universal vac gauge to it (these usually have both positive and negative pressure dials) via a old oil fill cap with a drilled in nipple so the vac/pressure gauge line can hook to it and crank up the car and see if excess pressure is happening.

Other wild card, oil that sat in the turbo is cooked and its cooked a little on the internals causing a mild restriction thus increasing pressure overall on the system. To clean that out just go run the car until it got hot and naturally clears it out with a hot oil bath.

Wow I'm dreaming up crap tonight!

My top methods first:
1. Change Oil filter
2. Start the car and open the oil filler cap to see blowby (yes usually engines pressures go down with increase blowby, well there is a turbo factor here that could affect this usual observation).
3. Drive your car, heat that turbo up for a internal hot oil bath to remove any cooked oil narrations internally. Once nice and hot, drive home and let her idle for 10 or so minutes to cool the turbo down.

If last one does the trick then change that extra crispy oil (even though it only has 300 miles). I'm applying some diesel ideas on the whole hot turbo siting still with the engine off and cooking or formally know as oil "coking". All turbo vehicles deal with this, its mostly turbo race cars that deal with it and those hot stinky diesels I play with.

silverz28camaro

iTrader: (20)

what kind of pcv setup do u have?

#AngryTransAm

This is a good question to ask above.


I almost recommended to check the pcv but didn't want to chase the engine crank pressure possiblity too much. Obviously a lot of blowby showing with the car running with the oil fill cap off would point you toward the Pcv system as a whole and then point toward worn cylinder walls (compression test wouldn't hurt to do too) then point toward the turbo system over all possible affects on crank case.

silverz28camaro

iTrader: (20)

post up some pics of the engine pcv setup

HossinatorSS

iTrader: (1)

Sorry for the delayed response.

Thanks for the oil filter idea. I will try that. Maybe I got a bad one? The problem didn't occur in the 300miles between oil/filter change and parking it but maybe something flowed in and is clogging it.

Those 300 miles were about 50/50 split highway and city driving. Nothing special, maybe some a wot run through second here or there. My commute is like 5 miles round trip and traffic doesn't exist here. So they weren't hard miles. Also, when I change the oil: I drain the pan, change filter, replace oil, pull oil cap and put in a 1/2gal jug, start car, let oil-return run into jug until it goes from black to color of Mobil 1. This way I get all the nasty oil out.

PCV system: I have the STS CARB-legal pcv setup. The stock pcv feeds to an STS switch/valve and the outlet from that is piped back to the turbo intake pipe (between the air filter and turbo). So that tube should always have vacuum on it. I've never had signs of oil in this pipe. I will try running the engine with the oil filter cap open. I ran the engine like this while checking return-pump flow but I don't believe I checked the oil pressure with the cap open, I was just looking at return flow. Maybe the pcv switch is crapping out?

I might not be able to run it for a few days as I've got all the pipes off for cleaning since I found oil in the pipe that turns up to the MAF. I'll post as soon as I have news.

P.S. On a plus note, I did find a reason why I wasn't making max boost. See pic (flashlight shining into pipe). Good thing I have an extra pipe laying around.