Oil Pressure Gauge

Can someone tell me what is causing the oil pressure gauge in my 911 to peg immediately after starting. The gauge never changes until the motor has been turned off.

If this the gauge itself, wiring or the sending unit?

Thanks in advance for any help.

When my sender failed, it caused the meter to read full scale. Replacing the sender fixed my problem.

My 78 911 does the same thing. When the engine is warm the viscosity of the oil is higher thus creating a higher pressure. As the engine warms up, the oil viscosity changes and the oil pressure drops. I use valvoline 20-40 racing oil - havn't had a problem. I did however change out the oil pressure sending unit because the other one was leaking. It didn't affect the way the pressure gauge operated when it was cold versus when it warms up.


Steve

I had the same problem on my 73, I ended up replacing the sending unit. But you may want to test it by shorting it out and if it returns to zero then the sending unit on the back of the engine has failed.