OIL PRESSURE

"After driving rather hard and when coming to a rapid stop, my oil pressure drops below the number 1 bar and the low oil pressure light comes on. As soon as you blip the throttle, it goes back to normal. " "The car is a 2002 C2 with 35000 miles. The oil pressure while driving appears normal between 3.5 to 5 bar. The oil level is kept about 2 bars down from the top of the electronic oil level indicator. The outside air temperature today was 100 degrees." Having same problem...anyone know the fix?

Just had identical problem. Not a fun moment when the light first came on and I shoved the clutch in and dove for the curb to shut the car down. But oil level was good and I did not hear any scary sounds so I cautiously drove it home. I really debated having the car towed or driving it to my independent. Chose to drive and it ran fine with the gauge showing normal operation. My shop inspected everything and replaced the oil pressure sensor. There was no fault code, but the computer did register an electronic 'event.'

not to start an oil thread... but what were the ambient temps and what oil are you running

Thanks, I replaced oil pressure sending unit. Both times this happen outside temp was 95++, fuel low, running very hard. After opening fuel cap symptoms went away. I replace fuel tank pressure valve and thought I fixed the problem.

Temp 100, oil M1 0w40.

Would 15w-40 fix the problem?

15w-40 could help. What are the rpms when you stop, ~700 or is it lower?

Just a thought: See part #23 and 24 in this exploded view http://dcauto.gotdns.com/illustratio...35#90037815109 also this thread https://rennlist.com/forums/996-foru...-question.html

Just drops under 1000rpms.

Thanks, my 2000 996 had this replaced also. I thinks I have a new spring somewhere, I will give it a try...this sounds like a fix!!!!

In 100 degree weather you might consider another oil though I am sure not all will agree. I really dought its a major issue but watch it to make sure its not frequent

Quotes source post: 8708898

Not if the problem is a bad or misbehaving sensor. If the engine really had an oil pressure problem moving to a heavier oil just kicks the problem down the road a while longer. The real problem is not the oil being used but the engine has increased bearing clearances (or something else internal possibly not related to bearing wear but simply wear) that ups the engine's oil budget over and above what the oil pump/oiling system can supply. And it has plenty of margin so if the engine's oil pressure is really too low... Sincerely, Macster.

"Oil pump screw plug pressure relief piston" part # 24 from above. Cann't remember if you need to drain the oil first to replace spring? At that temp, will it make a difference? if not tracking.

Apologies to the OT but i just wanna ask, what could be some possible reasons why the needle on the oil pressure gauge does not stay steady? I can see the needle move a tiny up & down ...

Quotes source post: 8709652

If it does there's a problem and it is not the oil. Engines vary but not much, if they're healthy. I've had my cars through hotter temps than 100F with Mobil 1 0w-40 oil and never had any oil pressure problems. I have I"m sure mentioned the 116F air temp I drove through and 226F coolant temp and God only knows the oil temp my 02 Boxster manifested one blazing hot summer day in southern AZ. The engine had relatively fresh (Approx. 1K miles fresh) Mobil 1 0w-40 oil and suffered no signs whatsoever of any oil pressure issues. While I have not had the Boxster in that high of heat since, it has seen 100F+ temps during the hotter months where I live and drive. So has the Turbo. In fact the Turbo experienced 118F and even 119F for a few minutes between the 118F temp readings one summer day again in AZ but this time between Kingman and Needles CA and points east. Even at 80mph (or off the freeway in Kingman or Needles and driving on surface streets) and with the A/C on to keep the cabin at a cool 72F the Turbo's oil pressure never showed any effects from the temps. Had I not had the outside temp reading to let me know how hot it was outside of the car I could not have told you the temp was anywhere near that hot from the oil pressure or the Turbo's coolant gage needle. If at 100F and reasonably fresh Mobil 1 0w-40 oil (or any other approved oil) and if the engine is not able to produce enough oil pressure to keep the oil pressure light from coming on and the oil pressure sender and in fact the entire oil pressure warning/gaging system is in good working order -- in short the low oil pressure reading is not due to something other than low oil pressure -- then the engine's actual oil pressure needs to be verified and if found to be too low the cause determined. It might be an oil pressure relief valve spring or relief valve proper problem. It might be one of the pressure valves that routes oil to the piston oil jets and is supposed to shut off under low oil pressure conditions but instead has stuck open and the low oil pressure condition is sort of self inflicted. Sincerely, Macster.

sounds right...Turbo is a differents setup than the 968 or 996. I'll try the relief valve spring first. Thanks

Quotes source post: 8709779

Yes, but these engines have a lot in common in the oiling department even though the details vary. All car engines depend upon the same fluid dynamic principles. It is not like the Turbo can exist in its own world in which these do not apply. If your car's engine oil pressure if fluctuating, if the low oil pressure light is coming on and you are sure the oil level is correct, the engine has the proper type of oil in it and the oil is reasonably fresh (oil can lose its viscosity over time due to water/unburned fuel contamination) then you need to verify the oil pressure monitoring/reporting system is working properly. Most of the time the low oil pressure cause is a sensor or wiring problem. But if it is not then the oil pressure needs to be checked with an oil pressure gage at the engine or at some oil pressure test point (usually at or near the block) and the real oil pressure readings noted. If they are not in spec (too low or less common too high) the cause needs to be found and fixed. Running a heavier oil is a bad idea, it is an attempt to mask or make believe a problem doesn't exist. Another risk is the heavier oil while it might bump up the oil pressure the flow may not be that much and other portions of the engine may suffer from lack of oil and those areas that were ok to begin with will soon not be. For instance, the camshaft lobes and their mating lifter faces are splashed lubed from the oil that comes from the lifter bodies that is around the lifter body and its bore. (That is at least the way my Boxster engine's cam lobes are lubed and I think Porsche used this same way in its other car engines.) A heavier oil may have this oil flow curtailed or the splash pattern affected so the cam lobes and lifter faces run with an unsufficient supply of oil. Sincerely, Macster.

oil pressure releif valve is a good suspect.

Ok, i agree with the oil grade. I found two new springs 996.107.127.53 Going to install.

There is also the possibility that the new sensor you replaced is bad. It happens.

Replaced spring, I will order a new ref valve, The 997 version has a tapered end. 997.107.125.01.

LOOKING GOOD...just ordered the upgrade piston.

I do wonder if high outside temperature had some impact on these issues. It was nearly 100 degrees when my light came on.

Oil does run thinner the hotter it gets so it doesn't cause as much back pressure.

If the " relief valve spring " is the cause then the higher temp will cause the spring to be softer. High temp will cause the piston to be tighter also. Old pistion showed slight wear marks. The upgrade piston is tappered...less friction?

Quotes source post: 8712507

No way the oil can reach any temp that would affect the relief spring's springiness cause the spring to lose tension. The piston gets larger as it heats up, but so does the hole it fits in. Both the piston and the surrounding metal run at the same temp. However, what can happen -- I've observed this in other assemblies -- is a small diameter hole in a large piece of metal, as the metal is heated up say with a rosebud torch tip (used to preheat items prior to welding them) the hole's diameter will shrink slightly as the metal heats up unevenly and the metal that surrounds the hole expands. But once the entire block of metal is at an even temp the hole's diameter returns to its size. But in the case of this oil relief piston and its bore, it is fed oil, high pressure oil, and the heating up of both the piston and the surrounding metal is fairly even. The piston's fit in the bore is a sliding fit and this takes into account possible uneven growth from heat: The piston getting a bit larger while the hole remains the same size or even gets a bit smaller for a while, until the temperature gradients diminish. The scoring can come from metal to metal contact but more likely is from particulate matter in the oil that gets between the piston and the hole it fits into. The tapered end may be a nod towards addressing possible uneven heating or it may just be a way to make it easier for oil to make its way between the piston and the hole in which it fits. Sincerely, Macster.