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To start, I have read for hours on forums to find a cure. I have a 2012 Silverado 5.3 (LC9) 1500 with 134,000 miles. I have had low oil pressure on the gauge and the P0521 code. So I replace the oil pressure sensor and put a new screen/filter under it. *Note, I did not pull one out before hand, so it didn't have one.  The pressure dropped for the first and only time to shut the engine off. So I removed the damn filter/screen and changed the oil again.  After this I replaced the pick up tube O ring and cleaned the oil pan.  Once again I was good for a couple hundred miles and the O ring did not seem to make a difference. I'm using a AC Delco filter UPF48R and Mobil 1 synthetic 5w-30. For a couple hundred miles I cold start at 40 psi, then roughly 22 at idle. Then the pressure drops after those couple hundred miles to roughly 25 psi highway. AFM is disabled (HP Tuners) and I have a catch can for the PCV reroute. Everything else is stock. 

 

I would love for some help on this since I seem to be a wit's end now. My next thought is mechanically test the pressure at a dealer and most likely a new oil pump... I have read about people with this same issue and a new oil pump doesn't solve this.

 

Edited by zamocks

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39 minutes ago, zamocks said:

To start, I have read for hours on forums to find a cure. I have a 2012 Silverado 5.3 (LC9) 1500 with 134,000 miles. I have had low oil pressure on the gauge and the P0521 code. So I replace the oil pressure sensor and put a new screen/filter under it. *Note, I did not pull one out before hand, so it didn't have one.  The pressure dropped for the first and only time to shut the engine off. So I removed the damn filter/screen and changed the oil again.  After this I replaced the pick up tube O ring and cleaned the oil pan.  Once again I was good for a couple hundred miles and the O ring did not seem to make a difference. I'm using a AC Delco filter UPF48R and Mobil 1 synthetic 5w-30. For a couple hundred miles I cold start at 40 psi, then roughly 22 at idle. Then the pressure drops after those couple hundred miles to roughly 25 psi highway. AFM is disabled (HP Tuners) and I have a catch can for the PCV reroute. Everything else is stock. 

 

I would love for some help on this since I seem to be a wit's end now. My next thought is mechanically test the pressure at a dealer and most likely a new oil pump... I have read about people with this same issue and a new oil pump doesn't solve this.

 

Try Melling 10296 high volume pump IF everything else checks good. (manual pressure check and other sources of leaks stopped) 18% more volume that the factory pump. The point of this pump is to restore pressure and flow to high mile Gen III and Gen IV motors whose ring seal is good enough yet to delay rebuild. Rod, main and cam bearing clearances are getting larger and increasing leakage. IMHO of course. Just a thought. 

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i agree with the last post...clearances in the pump, cam and crank add up as you pile on the miles. Maybe move up to a higher weight, 10-30 at first. Get ready for a rebuild... 

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Switching filter brands could bump pressure too.

 

There is also a oil pressure relief threaded into the oil pan at the oil filter housing area. You have to remove the pan to get at it. A lot of people remove it and replace it with a threaded plug on camshaft swaps. Should give you a 5-10psi bump is pressure from what I've found.

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If I use at Melling pump I've heard I get roughly eight more PSI for oil pressure out of it. Does this impact the AFM lifters at all in a negative way? Currently I'm running roughly 30 PSI at 65 miles an hour. Do I need to remove the oil pump inlet tube bolts to get the oil pump out?

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I have extremely similar issues in my 2007 vortec max. 276K miles.

I replaced the Relief Valve in the oil pan with a plug (I used a m14x1.5 drain pan plug from Autozone)

I replaced the vlom manifold with the ls2 (no solenoids and such but still has oil pressure switch bung)

Now im looking at doing an oil pump - Melling 296 as Grumpy Bear mentioned

 

Ill update here when I do it - good luck man

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Well Guys, I swapped the OIl Pump....as well as the entire truck. 

Proud owner of a 2014 Sierra Denali now.

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On 2/17/2020 at 7:09 PM, zamocks said:

To start, I have read for hours on forums to find a cure. I have a 2012 Silverado 5.3 (LC9) 1500 with 134,000 miles. I have had low oil pressure on the gauge and the P0521 code. So I replace the oil pressure sensor and put a new screen/filter under it. *Note, I did not pull one out before hand, so it didn't have one.  The pressure dropped for the first and only time to shut the engine off. So I removed the damn filter/screen and changed the oil again.  After this I replaced the pick up tube O ring and cleaned the oil pan.  Once again I was good for a couple hundred miles and the O ring did not seem to make a difference. I'm using a AC Delco filter UPF48R and Mobil 1 synthetic 5w-30. For a couple hundred miles I cold start at 40 psi, then roughly 22 at idle. Then the pressure drops after those couple hundred miles to roughly 25 psi highway. AFM is disabled (HP Tuners) and I have a catch can for the PCV reroute. Everything else is stock. 

 

I would love for some help on this since I seem to be a wit's end now. My next thought is mechanically test the pressure at a dealer and most likely a new oil pump... I have read about people with this same issue and a new oil pump doesn't solve this.

 

So where are you at with this?

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