just got a recent rebuild started, mechanical gauge (snap-on) shows a healthy oil pressure (75psi at 2500rpm), however the dash gauge causes me to worry. on startup the dash guage will jump to 45psi, then slowly drop over the cource of 3-4 minutes to 15psi. when the engine gets hot this time can be reduced to 1-2 minutes. if the key is cycled off and then restarted it will show one pressure, then slowly cycle down again. while i know dash guages can be very inaccurate (as is being illustrated right now) i still like them to be somewhat reflective of whats going on. neither the sender nor the dash guages have chnaged between the motors, and the extra sender i have is shorted, so its not an option.


wondering of anyone else has ran into this? it seems very resistance related.

 

I doubt it's the gauge.
It's most likely the sender.


-Ted