No oil pressure indicated 2007 Tahoe 5.3 LT 72K miles

[LittleFish]

1 minute after startup, oil drops from 30 psi to 0 psi. No indication of pressure loss (lifter clatter, knocking, etc). 72K on the engine driven pretty easy overall. Oil changes done on time and use a good filter at all times (Wix, Bosch, Mobil1). I have plenty of oil in the pan indicated on the dipstick and no leaks seen. What is the possibility of a clogged oil pressure sensor filter or just a bad pressure sensor at 72K miles? I used to run Chevy engines for 150K miles years ago while driving company service trucks with no problems. I went looking for the $15 dollar pressure sensor on the block as in the old days and could not find it. Now it is BURIED in the back of the block in a near impossible location. Any ideas?

 

[wjburken]

1 minute after startup, oil drops from 30 psi to 0 psi. No indication of pressure loss (lifter clatter, knocking, etc). 72K on the engine driven pretty easy overall. Oil changes done on time and use a good filter at all times (Wix, Bosch, Mobil1). I have plenty of oil in the pan indicated on the dipstick and no leaks seen. What is the possibility of a clogged oil pressure sensor filter or just a bad pressure sensor at 72K miles? I used to run Chevy engines for 150K miles years ago while driving company service trucks with no problems. I went looking for the $15 dollar pressure sensor on the block as in the old days and could not find it. Now it is BURIED in the back of the block in a near impossible location. Any ideas?

There are a couple things that can cause this to happen.

1) Bad pressure sensor and yes, it is a real PITA to get to.
2) Plugged screen below the oil pressure sensor.
3) Cracked o-ring on the oil pick-up tube where it goes into the oil pump. This requires dropping the oil pan to fix but is very common.

Some people end up removing the intake manifold to get to the oil pressure sensor but it is possible to do with out doing so.

 

[swathdiver]

1 minute after startup, oil drops from 30 psi to 0 psi. No indication of pressure loss (lifter clatter, knocking, etc). 72K on the engine driven pretty easy overall. Oil changes done on time and use a good filter at all times (Wix, Bosch, Mobil1). I have plenty of oil in the pan indicated on the dipstick and no leaks seen. What is the possibility of a clogged oil pressure sensor filter or just a bad pressure sensor at 72K miles? I used to run Chevy engines for 150K miles years ago while driving company service trucks with no problems. I went looking for the $15 dollar pressure sensor on the block as in the old days and could not find it. Now it is BURIED in the back of the block in a near impossible location. Any ideas?

Bobby, if you add two more quarts of oil and the pressure stays up, it's the o-ring.

 

[LittleFish]

Folks, here is what I did. Placed the truck on a hill, added 2 quarts of oil, put ramps in front of the rear tires and pulled up on the ramps. The back bumper is about 30 inches above the front bumper. Started the Tahoe and watched it for about 10 minutes. After 5 minutes with no temp increase showing (temp gauge still on low peg at 160) pressure stayed around 40 psi. As the temp gauge started increasing up to 190 deg, the oil pressure went to 30 psi at 1500 rpm. 3 minutes later the oil pressure switch said it was a 0 psi. I shut the engine off. Waited 2 minutes and restarted the motor. Oil pressure went to 35 psi leveled off and then started dropping. I seems like there may be a screen plugged or the sensor hold for the oil pressure may be plugged and then draining when the motor is shut off. All this time there had to be enough oil in the pan to cover the oil pump intake on the crankshaft where the "O" ring is located. It heads to the shop Monday. I highly suspect that a screen and oil pressure sending unit may be it. At no time did I lose pressure to the lifters or they may have started to rattle. Just my guess. Please give me back my 60 4Dr Belair with a beefed up 283 and quadrajet!

 

[YukonCrazy]

Had the oil pressure alarms going off on mine last year and it ended up being that damn little screen.

 

[OR VietVet]

https://www.rockauto.com/en/moreinfo.php?pk=7103956&cc=1433255&jsn=2311

https://www.rockauto.com/en/moreinfo.php?pk=8742996&cc=1433255&jsn=2316

Sounds like these are in your future. I would do both because what may be clogging the filter may also be in the sensor.

What oil do you use and what oil filter?

 

[LittleFish]

https://www.rockauto.com/en/moreinfo.php?pk=7103956&cc=1433255&jsn=2311

https://www.rockauto.com/en/moreinfo.php?pk=8742996&cc=1433255&jsn=2316

Sounds like these are in your future. I would do both because what may be clogging the filter may also be in the sensor.

What oil do you use and what oil filter?

Retired ExxonMobil after 26.5 years. Oil and filter are Mobil1 5w-20 (naturally!

Had the oil pressure alarms going off on mine last year and it ended up being that damn little screen.

 

[LittleFish]

Plugged screen, also had the Mech change out the sensor while he was there. He left off the screen as I have the V4/V8 mode disabled. It would go thru 3 to 5 qts of oil between changes. Now uses less than 1/2 a quart between changes. Best way to disable is to have someone program the computer to raise the turn on temp for the V4/V8 up to 300+ degrees. Will never turn on. It still pull down avg of 18 MPG.