Typical Oil Pressure Gauge StartUp Conditions

[nullack]

Gday folks

What are people typically seeing when they connect an oil pressure gauge to their engine during cold starts? How long is it taking for full oil pressure to be achieved? What sort of pattern does the engines oil pressure take as it climbs up to full?

Thanks

 

[tomcat27]

it's been a few years since I had a mechanical oil pressure gauge installed in my car, but I seem to remember almost instant full pressure - certainly less than 1 second.

of course, I also had an instance where the stupid plastic line (that feeds the gauge) ruptered. what a mess! fortunately I noticed right away and no damage was done.

 

[George7941]

Full oil pressure within three seconds, and the increase is very linear and very quick. Once the pressure starts to build it very quickly (within a second) reaches full pressure.

When engine is cold, the oil pressure is, of course, greater than the hot oil pressure. This cold oil pressure can be greater than the setting of the oil pressure regulator valve because of the resistance to flow thru the regulator and associated oil passages.

Only time there is a greater delay in pressure build-up is after an oil change when air has entered the oil passages and there is air in the oil filter.

 

[nullack]

Can we assume that full measured oil pressure is the same as journal bearings lifting off the bearing in full oil pressure mode?

 

[pcoxe]

In a closed hydraulic system, the static pressure would be the same throughout the system. With regards an engine block, however, it is an open system with oil flowing out of various "orifices" which would be the bearing clearances. You are dealing with both pressure and flow. If there is sufficient volume of oil and no upstream restriction (ie, which side of the oil filter is the gauge attached for instance) the oil pressure should be pretty much the same as the gauge when entering the bearings.

 

[Chris142]

The 392 in my International. Just rebuilt it, has less than 1k on it. Been sitting overnight.

 

[nullack]

GOLD -thanks guys legends