Engine looses oil pressure

wibednaroski

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I have a 1992 Silverado with a 4.3l TBI runs strong but for some reason when it gets to operating temp (just under 210.) it looses oil pressure and starts makeing a sound similar to a bad bearing but it drops a few degrees and completely stops and I get full oil pressure (30 psi) almost like it’s on a switch any help would be appreciated.
 

stutaeng

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So the pressure fluctuates on the dash? You need to check with a mechanical guage before you do anything. The dash guage is not that accurate to begin with, i.e., "20" on the dash is not 20 "psi" of oil pressure.

I had an 4.3 Vortec engine that did the same thing when it reached operation temperature. The Check gauges light would come on, and the oil pressure gauge on the dash was below the first registering mark. Mechanical guage showed 5 psi. It still ran fine when I eventually pulled it. No knocking.

The fact that yours makes a sound is concerning though. Be prepared for the worst.

Good luck.
 

Nick_R_23

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Sound indicative of worn bearings (main, rod, or cam) which have too much clearance and allowing too much oil through. Usually noted by good oil pressure when cold, but low to none when at operating temperature. The knock sound may be lifter clatter due to insufficient oil pressure to keep the lifters pumped up, or it may be an indication of a spun bearing in the early stage.

As the poster above mentioned, verify your pressure with a mechanical gauge to be sure. But from the sounds of it, you likely need an engine rebuild.
 

Schurkey

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when it gets to operating temp (just under 210.) it looses oil pressure and starts makeing a sound similar to a bad bearing but it drops a few degrees and completely stops and I get full oil pressure (30 psi)
I have NO IDEA why "a few degrees" would make such a dramatic difference in your oil pressure.

However, if there were electrical issues in the instrument cluster circuit board, or some other electrical fault, I can imagine the gauge being inaccurate. That doesn't explain the sound you're hearing, though.

As already said, diagnosis starts by plugging in a known-good, stand-alone oil pressure gauge to the oil pressure port, so that none of the existing oil pressure hardware is used for testing. Verify actual oil pressure at various RPM including idle in-gear, and various engine temperatures.
 

BOOT

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Could be a lot of things LOL I bought a truck cause it ran great n I've seen bad gauges on these trucks more than once but for me it was a cam bearing. As mentioned check with another mech gauge like I did. Vlogged about it if you need an example.

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