Oil Pressure Problem

gbailey911 · 01-04-2009, 12:38 PM

I posted this on the Rennlist site and thought I would post it here to get any additional thoughts on my problem.

Thursday I took a 500 mile round trip in my 87 Carrera 3.2 to attend my Dad's 80th birthday. It was a beautiful day for a drive, clear skies and 30-40F temperature. The trip went with no problems...except my oil pressure gauge did not seem right. When cold I have seen close to 5 bars on the gauge with new oil and cold but yesterday the needle was pinned at 5 bars for the first 2 hours as I cruised at 3000 rpms. The pressure would drop to 2.5-3 bars at idle but would rise to 5+ bars once I returned to speed. I stopped after the first two hours for a lunch break, and after re-starting, my gauge was back to what I would call normal at 3.75 bars at 3000 and 1.5 bars at idle. After the party(3 hours off), I started home and the gauge was back to pinned at speed and 2.5-3 at idle. After three hours driving and a short off break, the gauge was back to normal until I got close to home, 1 hour later, and then it went back to pinned at speed.

The car ran perfect the whole trip with the slight distraction of the oil pressure gauge and the temp never went past the 1st line on the gauge. I am running Brad Penn 20w-50 oil, mahle filter if that makes a difference.

Does anyone know what could be wrong or what I should check as I know(think) my pressure is not that high?

As always, thanks for looking and thanks in advance for any thoughts!
__________________
George in Virginia Beach
1987 911 Coupe

spuggy · 01-04-2009, 12:54 PM

Loose or grubby connection to the oil pressure sender would be my first guess. Try cleaning and tightening the spade connectors.

scottbombedout · 01-04-2009, 01:14 PM

I've had the exact same problem. Was worried too, but its either just the connection or the pressure sender I would have thought.
The pressure sender is a PIA to replace but worth it for peace of mind.

gbailey911 · 01-04-2009, 01:15 PM

Thanks for the quick reply. I removed, cleaned and tightened the connector today and no change. The gauge still varies with rpms but is eratic. I have never hade 5+ bars of pressure at speed.

Formerly Steve Wilkinson · 01-04-2009, 01:32 PM

I seriously doubt there's a thing wrong with your lube system. It's a gauge, ground, connector or sender problem. Nothing has changed with your oil, oil filter, oil pump or internal system.

gbailey911 · 01-05-2009, 05:04 AM

The only thing that changed was I had to mix oils as I was out of Brad Penn oil so I added a half quart of Castrol 20W-50 before my trip. I can't believe this would make a difference???

Any thoughts??

Rick V · 01-05-2009, 07:24 AM

unhook the spade connector, turn the ign switch and observe the gauge. Then ground out the wire and again observe the gauge. If you get the full sweep then you know the gauge and wires are all good, and you should replace the sending unit.
Mixing the Castolr and Brad Penn will have no effect, you can drop that idea.

Formerly Steve Wilkinson · 01-05-2009, 09:27 AM

Ditto what Rick said.