Lost oil pressure

chevrolet
silverado1500

#1

where do I turn now? 2004 Chevy Silverado 5.3L 304,000 Miles. Started out with great oil pressure, parked it for a few months, started up fine, good oil pressure, went away for a week, started it and lost all oil pressure (lights, bells, valve racket, the whole 9 yards). To down the oil pan and found a huge mess, cleaned up pan, strainer, pickup tube, replaced o-ring. Great oil pressure. Ran great, quiet, full of power. took a 600 mile run to take some stuff to my daughters college. 10 miles from home lost oil pressure and here come the lights and bells again, but no valve chatter. Took and replaced oil pump, all gaskets, new WIX oil filter. Guess what happened-----still no oil pressure. even with 20w50 castrol oil still no oil pressure. checked with manual oil pressure gauge…still no pressure. Time for another engine? or does someone have something that i may have missed.


#2

On these engines, it’s very common for the oil pressure sensor to fail, resulting in a reading of either 0 or 80

If you want to do the right thing, hook up a mechanical oil pressure gauge and report the results back to us, before throwing parts at the engine

If you want to take a chance, and be quick, just replace the engine oil pressure sensor

Now as for that “huge mess” . . . just how long do you go between oil changes?

If the oil pressure sensor fixes your problem, use 5w30 at the next oil change


#3

He hooked up a manual gauge and no pressure plus valve clatter the time before? Sounds like a blockage somewhere?


#4

Yeah, somehow I missed that part about checking the pressure manually the second time

Seems weird that there was no engine noise, though


#5

Sounds like worn crankshaft bearings. You could Plastigauge them to confirm.

http://www.plastigaugeusa.com/how.html


#6

Nice explanation. I’d always heard of plastigauge but never really understood how it is used.


#7

There’s a spring & piston gadget that is involved w/regulating the oil pressure. Take a look at this link.


#8

But I’m assuming that part was replaced, because OP said he initially replaced the oil pump


#9

The oil pressure relief valve is in the oil pump housing that was replaced, I hope the oil pump was complete with the valve and spring installed.

With worn bearings there is usually some pressure measured at high engine speeds. To have no oil pressure there would have to be a serious oil galley problem, perhaps a galley plug was removed during the repairs and not installed tight or a push rod/rocker arm failure and the lifter has come out of its bore.