BillJ

Was wondering what the typical oil pressure is on the 993. The manual says that it should be a minimum of 3.5 on the guage at 5000 rpm. Mine sits right at the 4 mark when throttling and climbs to just over the tick at the 4 mark. At stopped idle it never drops below 1.5 even when real hot. Is this all in an acceptable range? Drove another 993 (96 targa) and noticed that it was sitting above the 4k mark under throttle and basically sat at 4.5 at 5k rpms

Flying Finn

Sounds normal.

In most 993s, pressure goes up to 5 at 2500-3000 rpm (but 4.5 in some cases which is normal) and when idling, it stays at 2-2.5.
When really hot, idle pressure can be 1.5 or so (a lot depends also what revs your idle is, some times people with automatic tranny see less pressure but that's because they're idling with "D" on.

geolab

As a matter of fact, each VDO oil pressure sensor shows a different reading, they are mal-regulated.
I had a problem with the Oil pressure light coming on sometimes.
Porsche diagnosed that they have previously installed an RS oil pressure gauge on my car which was very accurate and jumpy. It went above 5 bar at MAX. throttle, and 2.5 at idle.
Its accuracy and jumpy behaviour was the reason of the oil pressure light going on.
They changed the gauge, and the new one with full throttle showed a reading of 4bar on max. and 1 bar on idle.
I bought another one that showed a reading of 5 at full throttle, and idle at two.

In fact, I know that resellers play on this replacement in selling used porsches.
It is of great dollar value to sell a car with excellent oil pressure.

c993k

They all seem to be different but serve the same purpose. It's a good reference to the owner who knows what's normal for his car. Same goes for the other Oil gauge. Chris

fbfisher

I see that oil pressure can be effected by heat, can it also be effected by the amount of oil in the tank. My pressure range seems the same regardless of heat or level of oil.

geolab

Oil pressure has something to do with quantity theoretically. But the oil quantity in the engine is always the same, provided you don't let the oil level drop empty. The oil reservoir acts as a syphon to the system. And when oil level is low, the syphoning to the radiator and oil cycling in the engine would be less efficient for cooling with less oil.
The oil quantity gauge is in the reservoir remember, not in the engine.

But oil pressure is largely affected by heat, thus viscosity of the oil.
When oil is heated, it looses in its viscosity and thus become more compressable.
In other words, the oil pressure should drop with oil being hot.
Scenario in the porsche is that pressure gauge should about max on cold start.
And pressure should lye around 1-2 bar (depending on the humour of the gauge) with warmed up engine.

dhicks

Interesting discussion........the pressure gauge seems as variable from one car to another as the level indicator!!!

After an oil change mine shows 5 bar when cold and under revs....but when warmed up often is over 5 bar and seems pegged out when over 2500 revs.........after about 3000 miles (just before an oil cahnge for me......it will still go over 5 under laod but no longer pegs out at max.......when warm and idling........2.5-3 bar after oil cahnge and 2-2.5 just before oil change.......I dont think I have ever seen it dip below 2 bar.

geolab

I owe to be more precise on this one.
The VDO oil pressure sensor has a pin hole to measure the pressure in the engine, where the oil enters from this tiny hole to the sensor recervoir.
I have noticed that the wider the small hole is, the more accurate and less smoothly your gauge will measure.
I had a problem with oil pressure light coming on.
It came on when the rpm went lower than normal idle, in cases under electrical load, with litronic on and A/C button switched, or other electrical equip. turned on suddenly.
The needle dropped to 0.5 and back to 2 bar in a split of a second.
The light came on.
The hole on the sensor was 0.5mm compared to the others I installed with 0.1 mm hole.
with 0.1 mm hole, the gauge moves smoothly, thus no oil pressure light

trevi1

Hello my 993 1994 have a bad pressure reading. I start the engine and the pressure go to 5 (top) and only after 30 min it beging to work normal... And If you only drive the car at low RPM it never begin to work.... Can anyone see it?

ppashley

Low RPMs and zero pressure is a bad thing. Could just be a bad OP sensor. They do go wrong.

Here is a video of mine going wrong.

I replaced the OP sensor and now its fixed.



Perhaps that's your problem. Am sure others will chime in. Good luck.

SPIKES

i am assuming we are talking about the sensor on the engine that is the problem...and not the actual guage?
thanks

geolab

Yes we were talking about sensor on engine in sept 2006...deja vu

V

I had the same problem in my old car. My pcar mechanic told me that the oil pressure sensor often fails.. Sometimes the oil pressure went to nothing and when I tapped the guage face it went straight up to 5 bar again... I think this is a common problem..

ppashley

But lets not confuse these 2 seperate issues:

1. Cockpit gauge is faulty... gets stuck / doesn't work / works if you "tap it"

2. Oil Pressure Sensor is faulty ... sends inaccurate reading to gauge. (this was the issue I had)... inaccurate reading - either too low / also can "peg" to 5 bar.

Good luck fixing the problem!

Phil