Oil Pressure Gauge Oscillation

I've got an 84 Carrera, daily driver. Has run perfectly over the past two years. Prior to last week, once the engine made it to normal operating temperature the oil pressure needle registered 4 bars at 3000 rpm, and moved up and down smoothly consistent with engine speed. Lately, the needle has been oscillating quickly, the equivalent of 1 bar range, no matter where it is in the pressure range. The oscillation, or bouncing characteristic, occurs both when the pressure is going up or down due to changes in engine speed and also when the engine speed is constant. This is now happening during in-town driving, but it goes away completely during high speed freeway driving. The oil level and temperature guages are registering accurately and normally. Can anyone tell me if this is just the sensor or do I possibly have oil circulation issues?

My '83 sc has done the same thing since I've had the car. At a stead 3200 RPM and up, the needle stays pegged. I don't think there are any circulation issues here, maybe just a sensor on it's last legs.
Rich

My 83 SC also jumps around. Just a random jump occasionally.

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Robert Stoll
83 SC
83 944

Sounds like we're on the way to a consensus. Thanks for settling my fears! I'll have the sensor checked next week.

Bad sender, guys! Of course, you CAN VERIFY that the gauge is good by getting a 5,000 Ohm (or 10,000 Ohm) potentiometer and wiring test leads and alligator clips to the wiper (center) connector and one of the ends, then clip one lead to the gauge lead and the other to the engine block (or convenient oil pipe, and turn on the ignition, but don't start the engine! Sweep the potentiometer through its' range and note that the gauge needle moves steadily, not jumpy!
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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 03-28-2001).]