Oil pressure issue, non issue??

So when my gauge read that I was due for an oil change 2 days later my oil pressure suddenly drops to zero. From that moment on over the next week when I start the truck oil pressure goes to around 40 and slowly over 35 or 40 minutes driving to work it drops down to about 10 and occasionally drops all the way to zero. Yesterday I change the oil and filter and now oil pressure is up to now 45 and runs up to near 60 under throttle andhasn't dropped since was thinking it was an issue with the oil pressure sensor but now after running it a few times oil pressure remains a little bit High but seems to be holding, was wondering if anyone else has experienced this keep in mind I live in Wisconsin and it's been below zero for the last 2 days

Stentz63   

Had similar symptoms a few months ago. Pressure would drop be up and down
and then be fine for weeks. Then it dropped a few times went into limp mode
and then fine. So I changed the pressure switch all is well. Good starting
pressure, running temp, and idle good.    

Stentz63 said:

So when my gauge read that I was due for an oil change 2 days later my oil pressure suddenly drops to zero. From that moment on over the next week when I start the truck oil pressure goes to around 40 and slowly over 35 or 40 minutes driving to work it drops down to about 10 and occasionally drops all the way to zero. Yesterday I change the oil and filter and now oil pressure is up to now 45 and runs up to near 60 under throttle andhasn't dropped since was thinking it was an issue with the oil pressure sensor but now after running it a few times oil pressure remains a little bit High but seems to be holding, was wondering if anyone else has experienced this keep in mind I live in Wisconsin and it's been below zero for the last 2 days

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Did you check the oil level when the pressure was reading low?

Stentz63 said:

So when my gauge read that I was due for an oil change 2 days later my oil pressure suddenly drops to zero. From that moment on over the next week when I start the truck oil pressure goes to around 40 and slowly over 35 or 40 minutes driving to work it drops down to about 10 and occasionally drops all the way to zero. Yesterday I change the oil and filter and now oil pressure is up to now 45 and runs up to near 60 under throttle andhasn't dropped since was thinking it was an issue with the oil pressure sensor but now after running it a few times oil pressure remains a little bit High but seems to be holding, was wondering if anyone else has experienced this keep in mind I live in Wisconsin and it's been below zero for the last 2 days

Click to expand...

From your other post, looks like you're probably operating a Gen IV (AFM) power plant, from 2008.

The oil pressure sensors don't fail that often; however, the mesh screen underneath the sensor could be clogging.  

In the event of failure, the sensors usually fail "high," rather than low.  In your case, the pressure is all over the place.  

To be perfectly comfortable checking the screen, your composite intake plenum would have to be removed.  The sensor is situated directly behind it.  

All of this could be accomplished without removing the intake.  Depends how comfortable someone is at feeling, checking, wrenching components you can't see.  There are YouTube videos.  If intake gasket has never been changed, probably time to remove intake.  

Some throw screen away, & go commando.  I wouldn't do this.  Could have a detrimental effect on what's left of your AFM system.

At zero (0) PSIG, there would be lifter clatter that would make the devil's own racket.  If everything sounded normal, it could be oil sensor/screen related.

Another consideration would be in the area of the gerotor-style oil pump that was introduced in GM's clean-sheet LS family.  The pump bypass valve could be sticking.  You would have to remove pump, disassemble, then check for scoring on valve & bore.

Here are a couple of things that are must-reads for owners of GMT-800's & 900's.  Be patient with the first one- it's 15 pages.  All are relevant, but doesn't start to cook until a few pages in:

Low Oil Pressure

Here's one of the better articles on how to think about our oil pumps:

Choosing The Right Oil Pump

Good luck!

I drove my '02 only 12,000 miles in 3 years, got water in the fog/DRLs so had the housings replaced. That's when I spotted the loaded '04 Arrival Blue Z71, employee driven with 7,000 miles. I fell in love for the second time in 3 years and swapped my sweet '02  4x4 LPM I factory ordered with only 4x4 and side steps.

I only put 55,000 miles on it in 12 years before the speeding red light running kid killed it.  Since so low miles I had the oil changed about once a year. I lost some oil a few times, I had a 5 mile commute to work and I'm in Michigan, I'd arrive at GM early and run the truck to stay warm or keep cool before work, and during break and lunch. I had pressure problems several times, changing the oil solved it. Idling it wasn't good for it, I killed the factory battery under warranty once then again not running it and using the Bose XM and opening the windows and sun roof. I had a lot of enjoyment sitting in the truck    I got an Optima Yellow top deep cycle the second time I killed the factory battery. Never had a problem with running the battery down again.

I lost oil pressure and coolant with my short trips to anywhere in Flint I needed to go to get anything I need. When I had to rev the rpms to get pressure and heat or AC I knew it was time to add coolant and probably change the oil. Since I had so few miles I never worried I harmed that beast of an engine despite my abuse. I'd vow to watch my oil and coolant levels closer again. I really miss my Avalanche but I have a nice silver 6cyl. GMC Acadia 7 passenger FWD SUV with low miles and my old light blue 4 cyl. S10 Chevy ext. cab pickup truck with matching fiberglass topper and low miles. No car note and I only need one two passenger vehicle, the pair together are Detroit Lions colors and all I need, they get fair mpg and I will be on a fixed income after Jan, 1.

Seems as though we are having a similar issue.  My gauge is random, and all over. It keeps putting a message on the display of LOW OIL PRESSURE, but the truck runs normal. I just had my cluster rebuilt yesterday because some gauges were failing already. There's a guy here locally that replaces the cluster motors and bulbs for $70. I was told it's probably the sensor somewhere's on the block.

I looked at this forum as I am having a similar issue. My change oil light started flashing as well, and this happened, sometime around the same point and time.

Thanks!

I had my cluster rebuilt  too I lost the speedo and odom. and more. I ignored some check engine warnings and toasted the transmission, that was stupid. 

OOps.   

RB`s 2010 AV said:

OOps.      

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Yeah cleaning the MAF and replacing a couple other sensors would have saved me a couple thousand dollars.

2007 Avy LTZ w/ 138K miles on it. 5.3L

Ok, i too had a similar problem this morning in 10F temps.  My oil pressure indicated low and when i was coasting to a stop (when the truck will drop to 4 cylinder mode) the oil pressure gauge bottomed out and the dash started blaring at me "Low Oil Pressure, turn engine off".  So under a near panic attack, i pulled over, shut the engine down and started it back up hoping that my engine wasn't on the brink of burning up.  Same problem moments later so i pulled into a parking lot and checked the oil level with the engine shut off.  Plenty of oil withOUT the engine running.  I've been losing some oil recently and took it to the dealership because of a TSB about a valve cover and was told they would replace that and an AFM shield for the low low price of $1100.  I used a Diablo Sport to turn the AFM back on again after i've had it off for a few weeks hoping to NOT burn oil.  If the RPMs are kept up the oil pressure stays up.  I'll try to drive it home at lunch and check the oil or listen to the engine while its running.  Any other thoughts or ideas to look for on this?

i have 02 Avy and an issue with some gauges, ended up replacing the cluster with one from an 02 Escalate. Looks super sweet.