P0521 Code

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wsteele

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I haven't checked, but i doubt it has updated covers. Is installing the afm shield part of making the new covers work as intended? Or is that an extra precaution?

It is a separate factor. The conclusion the GM engineers came to was there was a chance the AFM pressure relief valve, under certain circumstances, could spray oil into the lower part of some of the bores of the cylinders, causing an accumulation of oil on the rings from the underside, exacerbating the stuck ring syndrome identified as part of the excessive oil consumption downward spiral.

It seems to be the consensus opinion, at least on the internet, that the valve cover is the biggest single improvement you can make in the area.

If you are burning oil due to stuck rings, then freeing them up (or replacing them) will be needed to fix the oil consumption once and for all. But if you are just burning oil because your valve cover is funneling oil through the PCV and back into the intake, the valve cover may be all that is needed to stop the downward spiral and correct the lion's share of the issue.

PS - The updated valve cover is model year dependent (a couple of different orifice sizes in the PCV), so if you decide to do the update, make sure you get the right one for the yr/model engine.
 
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Mickey_7106

Mickey_7106

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It is a separate factor. The conclusion the GM engineers came to was there was a chance the AFM pressure relief valve, under certain circumstances, could spray oil into the lower part of some of the bores of the cylinders, causing an accumulation of oil on the rings from the underside, exacerbating the stuck ring syndrome identified as part of the excessive oil consumption downward spiral.

It seems to be the consensus opinion, at least on the internet, that the valve cover is the biggest single improvement you can make in the area.

If you are burning oil due to stuck rings, then freeing them up (or replacing them) will be needed to fix the oil consumption once and for all. But if you are just burning oil because your valve cover is funneling oil through the PCV and back into the intake, the valve cover may be all that is needed to stop the downward spiral and correct the lion's share of the issue.

PS - The updated valve cover is model year dependent (a couple of different orifice sizes in the PCV), so if you decide to do the update, make sure you get the right one for the yr/model engine.
Awesome, thanks for the help!
 

89Suburban

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PS - The updated valve cover is model year dependent (a couple of different orifice sizes in the PCV), so if you decide to do the update, make sure you get the right one for the yr/model engine.
This is true and stated in the TSB. Just wanted to add my $.02 shit's worth of experience, I put a '09 cover on my '07 and it did not throw any codes or seem to affect anything negatively so far. Wasn't by choice, just they way things fell together at the time.
 

swathdiver

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i have this code that keeps coming back. Started this past weekend. Dash gauge appears to read about 20 psi lower than what i remember. i dont think it goes past 40psi at WOT. AC Delco shows these two part numbers for my vin 12673134 , 55488247 but amazon says neither one is compatable with my truck based on year, make and model. Wondering if someone could me help me with this and perhaps a number for the filter/screen?

Lastly, is there an oil pressure sensor relocation kit for these 5.3s? im sure down the road ill be having to replace this sensor again.

Thanks

Our LC9s don't run as high an oil pressure as the iron block motors. Mine idles in gear in the 20s when hot and cruising under 40, the bypass on the pump spring is 36 psi or so. Mine has the new driver's side valve cover and does not burn oil unless it spends time above 3,000 rpms.
 
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Mickey_7106

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Our LC9s don't run as high an oil pressure as the iron block motors. Mine idles in gear in the 20s when hot and cruising under 40, the bypass on the pump spring is 36 psi or so. Mine has the new driver's side valve cover and does not burn oil unless it spends time above 3,000 rpms.
Mine has always been over 40 psi while driving on the highway and about 60 psi at wot. That's why I thought there was something off about my oil pressure during the check engine light.
Screenshot_20210626-131056_Torque.jpg
 
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