Engine noise? Started w low oil pressure

Engine noise?!? 2011 Yukon XL denali with the 6.2. Left work and not even 5 mins in low oil pressure light came on, knocking noise Probably right around being fully warmed up. Pulled right into a shop who told me engine was seized. Oil was full, recently changed myself. Do my changes at 3k or less with quality stuff. Have only owned for 1.5 years but all fluids were changed at purchase and has run like a dream. Engine is obviously not seized. Tried the overfill on hill, didn’t stop. Running a thicker oil now with rislone, which has helped a bit. Pressure is now at 40 on startup and 25 when warm. Would typically take it to my uncle and start taking it apart but he sold his shop and is unable to help me due to recent surgery so no resources to do myself. This is my daily driver and the love of my life Any pointers on the sound or a good gmc knowledge shop in the Worcester, MA area?

SiWilli said:

Engine noise?!? 2011 Yukon XL denali with the 6.2. Left work and not even 5 mins in low oil pressure light came on, knocking noise Probably right around being fully warmed up. Pulled right into a shop who told me engine was seized. Oil was full, recently changed myself. Do my changes at 3k or less with quality stuff. Have only owned for 1.5 years but all fluids were changed at purchase and has run like a dream. Engine is obviously not seized. Tried the overfill on hill, didn’t stop. Running a thicker oil now with rislone, which has helped a bit. Pressure is now at 40 on startup and 25 when warm. Would typically take it to my uncle and start taking it apart but he sold his shop and is unable to help me due to recent surgery so no resources to do myself. This is my daily driver and the love of my life Any pointers on the sound or a good gmc knowledge shop in the Worcester, MA area?

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Oil pressure is not out of normal range now, is it still knocking? Id say afm failure if the knock went away.

25 psi and 40 psi is normal.

Still knocking???????

donjetman said:

25 psi and 40 psi is normal.

Still knocking???????

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Still knocking!

donjetman said:

25 psi and 40 psi is normal.

Still knocking???????

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Yes. This video is after the thicker oil. Pressure is up but still a knocking.

They could very well be separate issues that just happened to coincide with each other. That knocking is at the same frequency as valvetrain noise, so it’s likely a collapsed lifter.

When my oil pressure sensor screen in my 2012 was blocked, I would get the low oil pressure warning only at normal operating temperature. So I suspect that’s the root cause of your oil pressure issue - false indication.

Another possibility is that the loss of oil pressure was real but only momentary and mainly affected the VLOM. In which case there may have been insufficient pressure for that lifter to complete its transition from locked to unlocked or vice versa, causing it to bind. But I can’t think of anything that would cause only a momentary drop.

Yet another possibility is that the low oil pressure indication was correct, but that the root cause was a leaky pickup tube o-ring, causing their to be insufficient oil pressure for that lifter to complete its transition, again causing to bind.

@SiWilli You are having a lifter failure for sure. I just went through this. Stop running the engine and being to take it apart so you can examine the extent of the damage and then form a remediation plan based on your findings. I had a similar situation and mine turned out to cost about $2k in parts and tools and about a months worth of weekends.

Here is my initial post outlining my troubleshooting and diagnostic process:

Here is my second post in which I discuss how to put it all back together:

If you have any questions let us know

AFM LIFTER FAILURE AND DELETE Utube video:

I vote lifter as well.

I can never remember what year 6.2 didn't have AFM enabled, but had the components in place. Regular lifters can fail, too, though.

I agree- STOP RUNNING IT.

iamdub said:

I vote lifter as well.

I can never remember what year 6.2 didn't have AFM enabled, but had the components in place. Regular lifters can fail, too, though.

I agree- STOP RUNNING IT.

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Here’s some neat trivia: The 6.2L L92 actually had a first and second design.


The first design, built prior to April 1, 2006 contained AFM components, but were left disconnected from the ECM.


The second design eliminated the AFM components altogether.

Mine was built after that date