A bad oil pump is obvious, but another possibility is the you spun one of your crank bearings, if you did, you will loose all pressure. Also, sometimes the actual gauges quit working. I would first make sure that your gauge works, maybe buy an after market one and hook it up to make sure yours is working. The vehicle that you have and motor, or any more information would also help me to give more ideas. Some vehicles are known to have problems with the gauges going to 0 and then right back up to 40 without any drop in actual pressure. example is an 88 - 92 silverado.
You may already know this but because it is winter I am going to say it just to be sure. When you start your car and it is cold the oil is thick and pumps a little harder resulting in higher pressure on startup but as the engine warms the oil the pressure gradually drops a little. I threw that in because my wife recently told me she lost her oil pressure and of course I was in a panic, but this turned out to be the case. Otherwise you already have some answers, good luck to you.
ST3V3N, He reported "Mercruiser engine" that could desire to be in a boat. First, if no longer achieved already, examine the gauge it is on the engine. those are greater companies to failure than in an vehicle. it is conceivable that the top gaskets are incorrect or have been put in incorrect, or the recent or re-labored heads stepped forward an oil leak. it would desire to be accident that the rigidity dropped after the top interest, in spite of the shown fact that it would additionally mean it's time to construct the backside end! As an edit to a submit added down, the heads DO have rigidity passages in them, it is how the valve practice is oiled, and the hydraulic lash adjusters fed. it is conceivable that the drop is there, yet i might nevertheless confirm the rigidity gauge. in case you have any rigidity at idle, you have to be ok for a competent mutually as though it is going as much as a typical variety as you run.
Excess component clearances or a bad oil pump are two reasons. However, you can't trust the dash gauge and need to hook a shop oil pressure gauge directly to the engine to read the hot engine oil pressure at idle. If it's above 12 psi, your engine oil pressure is acceptable in my opinion.
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A bad oil pump is obvious, but another possibility is the you spun one of your crank bearings, if you did, you will loose all pressure. Also, sometimes the actual gauges quit working. I would first make sure that your gauge works, maybe buy an after market one and hook it up to make sure yours is working. The vehicle that you have and motor, or any more information would also help me to give more ideas. Some vehicles are known to have problems with the gauges going to 0 and then right back up to 40 without any drop in actual pressure. example is an 88 - 92 silverado.
You may already know this but because it is winter I am going to say it just to be sure. When you start your car and it is cold the oil is thick and pumps a little harder resulting in higher pressure on startup but as the engine warms the oil the pressure gradually drops a little. I threw that in because my wife recently told me she lost her oil pressure and of course I was in a panic, but this turned out to be the case. Otherwise you already have some answers, good luck to you.
ST3V3N, He reported "Mercruiser engine" that could desire to be in a boat. First, if no longer achieved already, examine the gauge it is on the engine. those are greater companies to failure than in an vehicle. it is conceivable that the top gaskets are incorrect or have been put in incorrect, or the recent or re-labored heads stepped forward an oil leak. it would desire to be accident that the rigidity dropped after the top interest, in spite of the shown fact that it would additionally mean it's time to construct the backside end! As an edit to a submit added down, the heads DO have rigidity passages in them, it is how the valve practice is oiled, and the hydraulic lash adjusters fed. it is conceivable that the drop is there, yet i might nevertheless confirm the rigidity gauge. in case you have any rigidity at idle, you have to be ok for a competent mutually as though it is going as much as a typical variety as you run.
Excess component clearances or a bad oil pump are two reasons. However, you can't trust the dash gauge and need to hook a shop oil pressure gauge directly to the engine to read the hot engine oil pressure at idle. If it's above 12 psi, your engine oil pressure is acceptable in my opinion.
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Basically you hit few on the nose. There is the failed oil pump, blocked oil passages (dirty filter, sludge, etc.).
Other than that you can dig up all other reason why cars fail.
Good Luck.
a cracked block, a bad oil pump, leaky valves, bad head gasket, a bad rear main seal, a clogged dirty oil filter...
Wear and tear,age