cjoenck

I changed the oil pressure sender when I was fixing leaks because pressure was bouncing around when idle. With the new sensor, gauge is now stable but pressure at idle is below 1, oil light comes on, when engine is warm. Pressure does not reach 5 on freeway. So I was thinking:
- Oil pressure sensor is off, i.e. instrumentation issue with new unit or
- Old sensor was off and I am starting to see an oil pump issue developing that was masked by the old sensor.

What am I missing? While I was in there I also changed the pressure unit o-ring and the breather gasket.

I also changed oil to Joe Gibbs DT50 15W-50 Synthetic Oil from Swepco for the first time. How likely is it that a sensor is bad off the shelf? I had this one sitting new in a box on a shelf for about 3 years....

Vandit

5spd or tiptronic?

Ducks964

I have ran the Joe Gibbs DT50 once and quickly (~ 300 miles) switched back to Brad Penn. From what I had read it should be a very good oil for air cooled Porsches however I had the oil light coming on at idle almost everytime, once warm. So I cannot comment on the oil sender as a possible issue. I can just tell you my experience with the DT50

cjoenck

It's a Tip so it idles a little lower than the the 5speed.

jimq

my tip very seldom gets up to 5 unless its real cold.

cjoenck

That helps. However, I am more worried about the oil pressure light coming on when idling at a light. The oil pressure drops below 1 when hot and the lights get triggered.

My wife just reminded me that I noticed the oil pressure light for the first time after changing the sensor and before changing the oil. I thought I did both at the same time - apparently not, getting old.

So, taking the oil out of the equation for a moment, how accurate are these sensors and how much variance do they have? I can't find any tech specs on them.

I am still hoping it is a $60 sensor issue and not a $1,200 aging oil pump problem in the making.

Harry Apps

Ducks964

I have no lights with Brad Penn and lights at every stop light when warm with Joe Gibbs. I believe the 100% synthetic is your issue.

Olcha911

There is variance with the oil pressure senders- I have been through a few on a couple of 964s, and where one read a little over 1 bar at idle, another might read a little under 1 bar, etc. If you re-sealed the engine but did not touch the cam squirters, rod or main bearings, the only other thing that can/might affect oil pressure are the relief springs in the case. Brand new springs if the originals were 20+ years old will yield higher pressure at redline.

I'm in agreement that the synthetic oil is the cause of the low pressure at idle if nothing else was touched. Oil pumps are quite good on these cars- very rarely do you hear of a fault or a need for replacement.

-Keith