I just installed a SunPro mechanical oil pressure gauge. Once the engine is warmed up, the pressure goes to zero at idle. When driving, the pressure is around 25-35 psi. Is this normal for a mechanical gauge?

Thanks in advance,

shagster

No!!!!

It's normal to lose some oil pressure when the oil gets heated up and less thick.

It's not normal to have zero oil pressure on a mechanical gauge at idle.. how'd you hook it up? New gauge? What weight oil?

I used copper tubing that goes from the gauge on the pillar pod through the firewall, then across the firewall and down to the port in the block where the idiot light sender was originally. I used a metric adaptor kit which goes directly into the block, and then the stock fitting and line goes into that. I have found no leaks. Gauge is new.
I just started it up to check it again. After about a minute, the pressure is about 40psi, but drops to about 30 after idling for a while. Not long after that, it drops to 0.
The idiot light never came on before. Oil is full...10W30 There is only about 20K on the new oil pump and engine. Should I have the oil pressure checked professionally?

Thanks for the replies,
shagster

Could there be air in the line up to the gauge? You might try loosening the line at the gauge with the engine running, especially when it reads zero. That way you can bleed the tubing and verify that there is oil at the gauge.

X2, and I hope you put some loops in the copper line where it comes off the engine. If not the torqueing of the engine will work harden the copper and in time it will crack.

Bleeding air from the line won't change the gauge reading. The static pressure in the tube doesn't change with air present. The air compresses, taking up less space, but that doesn't affect the pressure.

Cheap gauges are notoriously inaccurate. So there is that to consider.

But there is also the matter of wear. Tain't a new engine, and things wear. The stock oil pump never was a high capacity unit, and they always dropped oil pressure quite a bit at idle. With time, those values will drop even lower.

You could consider replacing the bearings, or ignoring it until the engine spins one. And the latter may not happen for several hundred thousand more miles.