Oil pressure light flickers at idle/normal operating temp

[turbofiat]

Springs rarely "wear" but oil pressure relief valves do get stuck.

Well yes, that's what I meant. I've never opened up an oilpump but my guess would be the pressure relief valve is a spring. I guess in the case of a spring getting weak, I'd have low oil pressure, instead of too high.

[WhizzMan]

Just a few points to add to this discussion. The journal does not ride on a film of oil. It is supported on a wedge of oil that is constantly moving under the point of highest loading. The bearing is not round but instead wider at the parting line of the bearing so as not to shear oil off the journal because of bearing crush. Oil in a running engine is mixed with air. The journal does not spin true to the centerline of the bearing. The pressure in the bearing area is not what you are reading on the gauge.

It is amazing to me that the oil wedge can be only .0007 of an inch. That oil can work it's magic for a huge temperature range. Finally that a Maxi-dyne diesel engine can put out 900ft-lbs of torque at 1200rpm at the factory specification of 15 psi of oil pressure and last half a million miles between rebuilds.

Ah, something learned again. I love this forum for that.

In practice, the springs in the pressure valve almost never weaken or break. It is usually the valve itself that gets stuck or damaged because of debris.

[Guy Croft]

It doesn't matter if the oil pressure light flickers at idle/hot provided the gauge doesn't read zero at the same time * and provided the gauge jumps up when you 'blip' the throttle. A lot depends on the idle speed FWIW. When an engine is hot it can take a fair bit of cranking to get the red light to extinguish - even if it's only calibrated at 10 or 15psi, I see this on my littel test rig. However if you fire the engine up hot it goes out instantly - much, much faster pump speed, you see.

* This is also true of higher rpm loaded conditions eg: high G cornering, something I always tell folk using oil pressure accumulators.

G