Engine Oil pressure test gauge flickering

[Life4sk8]

Hi folks,

I am a long time reader here but it going to be my first post here.  I am the owner of a 996 c2 coupe 2002 with a 6 speed manual transmission.  Since spring, my oil pressure gauge in my cluster was flickering a bit.  When I steer rapidly to avoid an obstacle, the oil pressure on the gauge drop half a bar.  So I thought " hmmm maybe a bad sender". So I plug my engine oil pressure tester right on the sender port to test the oil pressure.  There is a difference in between the 2 gauges but on both gauges, I have more pressure than porsche spec.  Oil level is at maximum.  On the tester gauge, the oil pressure is fine and really steady until it reach 3.5 bar which is around 50 psi.  At this point, the needle is flickering really rapidly 2-4 psi until I let the rpm drop down so the oil pressure drop down too.  The oil temperature was at least 90 C.  Here is the link to a video I made from what I am talking about.  Thanks.https://youtu.be/zkyYkZcxcno

[DBJoe996]

Did not look at the video, but, I would start by making sure the oil is fresh and within spec, with a new filter, and replace the oil pressure relief valve and spring with the updated version.   It is a simple job.  Since you checked the oil pressure with an separate gauge, not likely the oil pressure sending unit.

[Life4sk8]

Thanks for the info.  Oil is 3000km old and the same with the filter. Mobil1 0w40 from porsche dealer and same for the filter.

[DBJoe996]

You need Parts 4, 5, 23 and 24 here (these will be the upgraded parts) - http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=996-99-05&section=104-00

[Life4sk8]

Thanks, I going to give it a try. Somebody told me too my mechanical gauge was a cheap one thats probably why the needle oscillating rapidly as you see on the video.

[Life4sk8]

I'll keep you post with the result.

[Life4sk8]

Ok just to keep you posted, I change the oil pressure relief valve, the spring and the piston. I got a digital gauge from winters to test the pressure. I change the sender unit. I check the oil pressure. It is in spec with Porsche in the garage with the good oil grade, good level and 3000 kilometer on it.  I did a road test and the problem still remain.  When I am on the highway driving at 100Km\h if I steer quickly to avoid an obstacle, the oil pressure drop for about 1 bar an come back at the right pressure... Like if my engine having oil starvation? But at this speed with regular tires?  So I thought "Hmm could it be the baffle in the oil pan? let have a look." Yesterday I remove the oil pan to look at the baffle.  It was in good shape.  Is the oil temperature have an effect on the shape of the baffle? Anyway I had new one from Porsche on my bench so I change it.  I doubt it could change something but will see. 

[DBJoe996]

Any debris in the oil pickup tube screen?  Any debris in the oil pan?  The only other thing that I can think of is the oil pump...maybe it is worn out.  I do hope that after re-installing the oil pan you will put in fresh oil and a new filter.  BTW, the OE canister cartridge type oil filter has a bypass valve in the bottom and the spring wears out.  Much better to get the LN oil filter adapter and use a non-bypass spin-on oil filter.

Edited July 12, 2018 by DBJoe996

[Life4sk8]

Only one debris was in the pick up tube.  it was on the oil pump side in the pick up tube... Did he fall in the oil pan from the engine or was he coming from the oil pump? I don't know but in was past the strainer on the oil pump side...  Does he fall with the oil dripping from the oil pump? I don't know. I never thought about the oil filter...  I have the ims solution here waiting to be install next winter.  So I would be able to use a non-bypass spin-on filter.  I tig weld a fitting with the old sender unit to be able to connect my test gauge and the new sending unit and test drive the car to see if both pressure react the same.  thanks for the heads up, I keep you post.