Oil Pressure Gauge

[Dave6T4]

I have an aftermarket mechanical oil pressure gauge under the dash on my car. It is fed by a straight copper tube. When the engine is idling, the needle bounces all over the place. I have another oil-filled gauge under the hood that registers 70 psi, with no bouncing. Do I need to put a couple of loops in the copper tube, to nullify the bouncing needle? If so, closer to the engine, or to the gauge? Should I buy an oil-filled gauge to replace this one under the dash? Thanks in advance for your input

 

[rickseeman]

You have 70 psi idling?

 

[Dave6T4]

Melling High Pressure pump, cold engine and oil.

 

[rickseeman]

That copper line you are using has been in use for 70 years or more at all different lengths so it shouldn't be the line. I would replace the gauge if it bothered me.

 

[eldubb440]

maybe bleed the air out of the copper line?

 

[Aron Gleason]

Get a #4 braided line.

 

[Bird 426]

The copper line should have a pigtail in it for vibration, engine to firewall, but that shouldn't cause your needle to fluctuate.

 

[dvw]

I wouldn't be surprised to see fluctuation with a large line at idle. Especially if it was an unbushed lifter bore roller. But with what I assume is 1/8" copper? Puzzling.
 Doug