928nomore

Was at Mo Sport in Canada 2 weeks ago running with the NNJR Porsche club and kicking alot of GT3 tail with my 07 z06. ( all stock except belts, carbotech pads, cooling ducts, Michelin slicks and haltech. )

It was warm and after 15 minutes or so of hard running i noticed the water temps rising to about 240-250 I also noticed that oil pressure dropped to below 50 psi even at 5k rpm. I did not think to check the oil temp but after pulling off the track and cooling the car down with a couple laps around the paddock, the water temps went back to 220 and the oil pressure returned.

Same thing happened on the next session after about 15 minutes of very hard running. This has never happened before. any ideas? The oil was just changed by the dealer and maybe they put in crap oil instead of the mobil one.

drove the car back 250 miles and never had another issue when it was not being pushed hard. ( oil levels were ok and I did not burn any oil)

RX-Ben

need to know oil type & visosity and actual oil temps, as a start.

GettReal

If it was a couple weeks ago, the outside temps were probably in the 100-110 degree area, that doesn't help any of what you are describing.

0Anthony @ LGMotorsports

Agree.

If the oil is 5w30 and it was 290 degrees, yes it is going to loose pressure as the viscosity of the oil is going to thin out.

rayk

I didn't like how Mobil 1 5w-30 thinned out at 240 degrees oil temp. I never had coolant temp go over 220 on the track even at 100 degree day with AC going(accidently).

froggy47

When my ls6 got those water temps I put in a Dewitt.

QIKSLVR

IMHO You need a 160° thermostat and to have your computer programmed to be on at 99% by the time the coolant is 200°

CGZO6

Dewitts

sebdavid

My oil pressures are around 30psi when oil temps reach 240. They can drop down a few more psi if oil temps rises to close to 250. At those oil temps, water temps are around 190 for me.

I use Castrol 5-40.

Devon at Powell Race Shop told me he wasn't concerned. I'm a bit uneasy but if he says so, I won't second guess him...

RX-Ben

30psi at what rpm?

sebdavid

Pretty much throughout the useful rev range (4-6k). Needle doesn't move much but it's pretty slow-witted and under WOT, 4 to 6k doesn't take much time...

RX-Ben

do you have an oil cooler?

sebdavid

Yes. I also have a high-volume oil pump, not the stock unit.

RX-Ben

Are both the oil cooler fittings on top of the cooler (or at least the "out" fitting)?

With a HV pump, you should see increased pressure. There is something wrong if you have a HV pump and are not well above 50/60 psi at higher rpm (which is what I see).

30psi is cutting is really close at higher rpm. Have you tried swapping in a new oil pressure sender to just be sure (they are cheap and commonly available)?

RX-Ben

Do you have a remote oil filter setup, by any chance?

sebdavid

I couldn't tell you about the oil cooler fittings, as I did not install it myself. I'm an ocean away from the car right now so I can't check either.

I was under the impression (from what I've been told) that there is a High Pressure pump and a High Volume pump, that both are different and that lower pressures are normal and not worrying with the High Volume one.

I have not tried a new oil pressure sender. But pressure seems to be accurate and goes up and down fine with RPM and temperature variations. For example when cold I'm getting pressures in excess of 60psi. When at normal highway operating temperature, pressure varies with RPM. On track, at high temps, not so much.

RX-Ben

A HV pump will result in higher pressures as the increased flow will increase pressure.
Check the orientation of the oil cooler fittings - you maybe getting an air bubble or something strange. Make sure the flow is in the proper direction, especially if you have remote oil filter(s).
If you have a DeWitts rad/oil cooler combo, then your oil takeoff block may have a broken pressure bypass valve (I think this happened to me).

sebdavid

I am running a separate oil cooler and radiator. I don't have a remote filter, filter seems to be in the stock location under the car.

Wouldn't an air bubble result in erratic pressure readings? Mine are consistent, just low at high temps under WOT and high revs. Drop in pressure is very linear as temps go up.

RX-Ben

Hard to say, I haven't had this issue.
The stock gauge reacts so slowly that it would not show any fluctuations, unless you hooked it directly to a datalogger that sampled the output many times per second.

Might be worthwhile to buy a couple caps (for the cooler) and a coupler fitting to take the oil cooler out of the loop and see if the oil pressure changes.

Another possibility would be an issue with the oil pump o-ring (damaged or pinched) which is causing loss of pressure.

sebdavid

How hard/easy is it to hook a more precise/faster reacting oil pressure gauge up? I am thinking I may not actually be getting the correct reading.

How would fittings on the oil cooler help?