Well it could be the sending unit for the gauge.
But odds are the oil pump or engine bearings are worn out.
As the engine warms up, the metal spaces expand and the oil gets thinner. The oil pressure drops some under normal conditions, but not more than 10 or 15psi. Normal idle pressure with the engine warmed up is probably 25psi.
You could check oil pressure with a mechanical gauge to make sure its not the sending unit.
Once the oil pressure starts staying below 20psi for long periods you'll start hearing noises.
i put a mechanical gauge on it and it ,,, well cold i start it it has a lttle left bank rocker noise for a few seconds and the oil pres. comes up to about 30 and i can go 7-9 miles come to a stop it goes to 0 i give it a bit of gas it comes up to 15 or so as i drive a while say 20 + miles it takes higher rpm to get the pres. back up but even then it barely does to maybe 5-10lbs. like i said i put heavier oil in w/ no effect. i did notice if it sits 10-15 minutes oil pres. comes up to 20-25lbs breifly(1-3 miles more). its has no noise at all.i figured it must be getting oil pres. it runs fantastic mega power. motor is supose to be fairly new you know how that goes!! "buyer beware" right? anyway i was hoping it might be something i was'nt thinking of or missed. ya think cam bearings?
Sorry I did not see this post when I said I hope its just the sending unit. The bottom line is, you will have to tear down the engine to find out what is causing the pressure to drop when the engine and the oil warms up. And if you have to tear it down, its always better to plan on rebulding it instead of just replacing one part. If the cam bearings are worn out, that means the rest of the bearings and the lifters are not far behind. Oil pressure comes from the bottom up, so everything along the way can be impacted by low pressure. Low pressure also makes the parts run hotter.
You could pull the pan and check the rod and main bearings, and go ahead and replace the pump and screen. Then if the pressure is still low, decide on a complete overhaul or not.
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SOURCE: Low Oil pressure light in idle at stop
Depending on the amount of miles, maintenance records, or how hard the car has been driven either by a previous owner, or by yourself. The engine's main crankshaft bearings or the connecting-rod bearings could be excessively worn.
Also, it could very well be a wiring problem to the sensor and/or computer causing the problem.
SOURCE: 1993 Chevy Blazer Oil Pressure
nothing ..normal low pressure at idle while hot ...but really should be thinking fresh oil change and filter soon..also what are the RPM's at idle hot in gear with A/C radio and other accessories running?
SOURCE: oil light comes on after car is warmed up
MOST COMMON ISSUE WITH THE OIL LIGHT IS THE ENGINE OIL PRESSURE SENDING UNIT, REPLACE IT, ALSO 3/4 SCALE TEMP IS NORMAL, THAT IS WHEN THE COOLING FAN KICKS ON, ABOUT 230 DEGREE'S F.
SOURCE: Oil pressure gauge goes crazy!
You had better check your dipstick and see if you have any oil showing on the stick? Sounds like your oil pump pickup is uncovering in a turn and cavitating which is caused by low oil quantity.
SOURCE: oil pressure drops to 0 at idle
OOO not good sounds like some of the head gasket got stuck somewhere, or the gauge or sender is bad or got knocked around when repairing the head gasket. I would check that first. If that checks out will need to drop the pan to see if something got stuck in the pickup tube,might as well change the pump while you are there. Or worst case some thing wrong with gasket job impeading oil flow back to bottom of the engine. Was the oil and filter changed ?if so pull out filter and see if an chunks are stuck in it now. And change oil and filter again. Sorry that was out of order I had a long day
If your oil pressure gets to low it can turn off the fuel pump. This may also have saved your engine. The ECM turns on the fuel thru the fuel pump relay for about 5 seconds. When engine is running oil pressure sender supplies the voltage to the pump. When engine shuts off check oil pressure and voltage to fuel pump.
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the motor has fantastic power an no noise at all.it will hold atabout 25-30lbs at 65-70 mph.
I hope its just the sending unit.
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