rockhouse66

I was hoping to blame this issue on how amazingly quick I am in the car, but then someone would chide me about the public road thing.
My oil pressure does dip in hard RH turns when the oil is hot. Whether that is oil starvation, aerated oil or ??, I don't know. That is what I am trying to learn with this thread. I probably should study where the pressure gauge gets its reading with respect to the engine bearings to help determine the possible effects. I don't much care about a momentary loss of oil flow or delivery of aerated oil to the lifters, but if the gauge is actually telling me that these events are happening at the bearings, that is an issue.

Mike Murphy

There you go. If it were simply the G-forces, it would have happened on the first few laps, so there must be something going on with the oil - temperature-related - that's a contributing factor. Here's a link: http://www.elephantracing.com/techtopic/oiltemperature.htm

Mike Murphy

For what it's worth, I Googled this issue and read a bunch of Corvette and Camero owners, some BMW folks, and a lotus all saying the same thing. It's always after many laps, maybe 15-20 mins on the track, and many times sweeping right hand turns. It seems like there's a common thread here with many different cars having this issue.

For those that have oil pressure that returns to normal after the long sweeping turn, it sounds like an oil delivery/pickup problem. But for those that have low oil pressure stay low even after pulling off the track and then report normal pressure after the engine has been off for some time, that sounds like foaming and/or temperature issue to me.

rockhouse66

I did look at the oil flow diagram and it appears to me that whatever you see happening at the gauge has already happened everywhere else in the engine. It is after (or possibly in parallel with) the gallery that feeds the crankshaft and the lifters.

Porschetech3

I'm going through the same thing on my 99 3.4 Cab 70k miles. I have only had the car 6 months and it was fine all winter but when the temperature got up I noticed the drop in psi on hard turns on the street. I have a 99 3.4 Coupe with 160k miles that does not do this. I can even make it do this going straight down the highway by snapping the steering wheel. I have replaced the sump baffle ( it had a deformed rubber door) , pulled the oil pump relief spring and piston and measured it (OK) , changed oil filter, changed oil sender unit. No effect on it. I'm thinking aeration of the oil also. Next I think I will pull the in-sump AOS's off and disassemble them, there is something weird going on. This car was overheated before I got it so I'm thinking it could have damaged the AOS's in the sump. It's the strangest thing I have seen in a while. Has your car been overheated at any point?

rockhouse66

I have only had the car for the last 8000 miles but no overheating that I know about.
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5CHN3LL

That you've had two 99's and they behave(d) differently makes my head hurt.

Porschetech3

Yea...It's beginning to make my head hurt also !..lol I have 2 99 996's a Coupe and a Cab also an 02 986s

Mike Murphy

Well, after my track event at Road America on Friday, I can report that I also experienced the drop in oil pressure on the long sweeping turn know as Carousel (turn 9). I take that turn at about 70mph-74mph, in gear 3, and on street tires (Michelin AS33+). I was running 15w-50 Mobil 1 for my track event, which meant I was at 5 bar pretty much everywhere except Carousel, where I saw it drop to 4 and if I was really pushing that turn, 3.5. My water temps were between 102-107C the whole day, and mostly were 104-105 (221F), which means that my oil could have been 220-240F.

I was able to reproduce this easily and not after many laps. It happened on the first as well as the last lap.

rockhouse66

The Carousel at Road America is a harsh test so not surprised. Your pressure is higher than mine, which normally runs at around 4 BAR when really warmed up and yours does not drop as low as mine either.

Mike Murphy

Yeah, my car for some reason has quite high oil pressure. I'm pegged at over 5 bar on any oil and any RPM above 1500 even when warm. I was reluctant to run 15-50 at the track and probably would have been fine with 0-40, but I probably gained 0.5-1.0 bar switching to this for the track.

As as much as Carousel might appear harsh, I was on all-season tires, not really pushing it too hard. There are plenty of on-ramps by me that I'm sure I could get the needle to dip on. I will try this one day and report back and after driving the car normally.

Kris Murphy

Another data point. I was at Pocono this weekend and the same thing was happening to me. First 10 minutes, everything is fine. Under throttle, I'm between 4-5 bar, regardless of if I am going straight, braking or turning. At about the 10 minute mark, pressure would dip to between 2-3 in the turns, come back up to 4 in the straights. I would come off the track at this point, by the time I made it to the pits, it was back up between 4-5 under throttle.

When it is driven on the street, this never occurs.

I have the FVD baffled deep sump, with extended pick-up. Spin on filter, running XP9. I have about 400 miles on the oil, so it could have been getting to the end of its life. One other data point, I was running Dunlop Direzza Star Tec IIs. So a sticky tire, but not a slick.

I plan to drop the pan, just to make sure there is no debris in the pick-up (I just installed the pan, and perhaps there is some stray gasket material that got released). I'll change the oil and filter (send it to Blackstone), and I will monitor at the next event. If it continues to be a problem, I will dig deeper.

5CHN3LL

For the record, oil starvation at the track is a documented reality, although there is still some arguing by certain folks about the underlying cause(s). This much talk about oil pressure drop issues on the street w/ street tires, though, is news to me.

Mike Murphy

If it can happen on the track with street tires and is repeatable by many different owners, then I can totally see how it would be possible on the street with some spirited driving, especially if the roads are twisty, the temps are high, and/or if elevation is a factor. I'm guessing track folks are just more aware of their pressures than regular drivers. And I'm guessing that some beginner track folks are slower on the track than others on the street.

5CHN3LL

Not arguing - but I'm also a little disheartened that a couple of people have chimed in to seemingly confirm that oiling issues can happen during "normal" street driving. Even if OP is a GOD behind the wheel, ANY car that shows oiling issues under normal circumstances is a disappointment. It really sucks when the car is a 911, and not a Daihatsu Charade or a Ford Festiva.