Blue Chip

Diagnosing an issue now... . 99 996 3.4 70K miles

Cold Start - oil pressure indicates 3.75 - 4.5.
Oil level good.
Not sure what oil is in it now.

After warmup - occasional pressure light when backing into the garage (I'm learning the clutch on this versus the 997).

Yesterday -

100 outside... Wasn't really pushing the car. 30 minute drive. Pressure starts fine then drops as the drive continues. Idle pressure (at lights) drops to .5 bar. As the ride continues - pressure light comes on at lights. Pressure will not climb over 2.5 bar at any RPM.

The way home (after 1 hour cooling off) was the same temp outside. No pressure lights came on, still .5 bar at idle - and consistent 2 bar at 3K RPM.

I have an oil pump piston and piston spring on order. I'm also going to change the oil to 5W40 (Motul) so I have a base line.

Step after that is a new sender.... maybe a trip to the indie to get a real read on the pressure?

Thoughts?

Schnell Gelb

Stock gauge is unreliable ,so yes get the pressure mesured by a competent Indie. Agreed replace the piston and spring regardless.The smart guys use JGDT40 oil + a spin on filter.

m3driver

Change the sender, it's cheap, easy, and can rule that out in a snap. Senders do go bad so it's not far fetched

johnireland

Agree with m3driver...the sending unit is the place to start...but don't assume it might be that until you know for sure. If the sending unit is changed and you are getting the same readings, have the oil pressure checked with a mechanical guage by a qualified shop. Don't try to raise your pressure by adding thicker oil. Also, if you haven't changed your oil recently, do so now and check the filer and the sump for any metal.

JTT

I would also agree with the previous 2 posters. This silly little sending unit, when on it's way out, can give you all kinds of misinformation. First indication with mine was oil pressure dropping to zero! After a change of clothes and some investigation it was this sender.

strathconaman

+996 Replace the sender.

ion_berkley

All good advice. New Sender for peace of mind. New (correct) oil and filter so thats a known quantity. Also think about cleaning the oil pick up pipe in the oil pan. It has a coarse mesh on it that could collect large debris and obstruct that path. No saying what that could possibly be...excess sealant from a previous oil pan opening or debris from the plastic timing chain guide, but it only costs you time, $10 dollars worth of new sump pan bolts, and a tube of sealant for further peace of mind.

Macster

Provided the re-seal of the oil sump plate doesn't result in any excess sealant applied replacing the sealant that the cleaning removed.

The sealant will make it through the mesh and be pulverized in the oil pump. This gets collected in the oil filter housing and is of course removed from the engine when the oil is changed.

The first oil change probably had some of this sealant trash in the oil filter housing oil and oil filter element.

If the oil pick up mesh was seriously blocked the engine would have expired by now.

billyboy

+1 on changing the oil pressure sender first. I had a similar problem and a new sender corrected it. Changing to 5W40 wouldn't help - the 5 is the cold start oil viscosity; the 40 is the running temp viscosity. Your problem is when the engine is hot.

Noz1974

You can also check the oil pressure relief Spring , it's easy to get at, it's accessible underneath the engine on the bottom of the oil pump without removing anything else , it's the single quite large hex bolt on the bottom of the oil pump, the spring inside can snap giving low oil pressure, obviously oil will come out when you remove it unless you do the oil change at the same time, also there is an updated Spring used on later cars which is slightly longer and can bring pressure up if you don't already have this!

RngTrtl

FYI. the sender is actually two senders in one unit. the first one gives you a variable reading for the gauge, and the other is fixed for the oil pressure light and the computer.

Schnell Gelb

But use the upgraded spring+piston

ion_berkley

Who knows...I've seen some pictures of god awful jobs (post-factory) done with way too much sealant. And then theres the old aluminum foil top from the oil container down the filler, a perennial favorite! I guess I'm paranoid about oil pressure.

Any more info on how that works? I always assumed this was a simple analog sensor since it has only 2 primitive terminals. Didn't think about it much when I replaced mine, I guess it could be a CAN bus connection.

RngTrtl

After removal of the stock unit there is a stamping on the hex nut of the pressures that each output measures. it says 0.3 +/- 0.15 bar, and says 0-5 bar for the other one. basically you have an on/off for the 0.3 +/- 0.15 bar that goes to the light and the computer for the dash screen, and then you have the other post that feeds the gauge. It is two pressure sensors in a single housing. Also, they are slightly different sizes so that you cant hook it up wrong. I dont think it is on the CAN bus, but i could be wrong about that, from what I could tell it is an analog output for the gauge, and a on off switch for the lights/computers screen. More than likely the gauge measure the voltage drop from the pin to ground controls the gauge off of that. the light/computer screen is looking for healthy voltage while above 0.3 bar +/- 0.15 bar. when the oil pressure gets too low the voltage crosses a threshold and pops the light and the computer screen.

Ahsai

100% accurate. Not on the CAN bus for sure. I don't think it's on the K-line either because its reading is not available on Durametric. However, that could be because it was not implemented by Porsche or it's implemented by Porsche but not by Durametric.