DOD delete but keep VVT?

You should have higher pressure off the pump.... But if that relief valve that's inside the pan is bad, it will dump your oil pressure quickly. And the oil goes past that before it ever reaches the filter.

I would "almost" just about bet on that being the issue. Could have a piece of grit in it as well. The reason I say almost... The metal you recovered out of the oil pan definitely makes me question the cam bearings.

One more note. Anytime you change the camshaft or crankshaft position sensor, and sometimes when replacing the timing chain, a relearn is necessary. Most bidirectional scanners are capable of doing that. At this point you really need to dig in and take a close look. If it is the cam bearings, you'll have to pull the motor. Crankshaft and whatnot has to come out as well. At that point you might as well be looking at a rebuild.

rdezs said:

You should have higher pressure off the pump.... But if that relief valve that's inside the pan is bad, it will dump your oil pressure quickly. And the oil goes past that before it ever reaches the filter.

I would "almost" just about bet on that being the issue. Could have a piece of grit in it as well. The reason I say almost... The metal you recovered out of the oil pan definitely makes me question the cam bearings.

One more note. Anytime you change the camshaft or crankshaft position sensor, and sometimes when replacing the timing chain, a relearn is necessary. Most bidirectional scanners are capable of doing that. At this point you really need to dig in and take a close look. If it is the cam bearings, you'll have to pull the motor. Crankshaft and whatnot has to come out as well. At that point you might as well be looking at a rebuild.

Click to expand...

Nope changed that too (Delco) , and put in the deflector shield. Wanted to block it off but didn't know if I could with the VVT. I did change the cam sensor. I know crank position sensors need a re-learn but thought cam were good to go. Well I have the scanner comming so we'll see if it comes back on.

If I remember right, I have read that the Aluminum blocks almost never have a #3 cam bearing walk and it's mostly an iron block problem. The #3 cam bearing simply does not have enough contact area to properly support the cam. You can buy longer bearings and also oversize OD bearings.
You can not change the cam bearings in the truck and the engine will need pulled but you can change the bearings with the crank and rods installed.
My engine is a 2007, L92. Flat valley cover and has VVT. When i got it the oil pressure was 10PSI hot or slightly less if I remember right. I also had shiny bits in the oil when I changed it.
I installed a Milling HV oil pump and new O ring. After replacing it the hot oil pressure is 23ish PSI after driving for an hour at freeway speed for a few months now. Maybe I caught it in time?
I have also read the DOD valley cover can leak pressure from the 8, O rings leaking under the cover.

j91z28d1 said:

15 to 19 hot idle but still dip in the red on the dash? that could be a few different things. you might move the mechanical gauge up to the sensor port. I'm 99% sure it's the same thread.


man these oil pressure threads are brutal. I've honestly never seen anyone post a solid fix. usually lots of parts replaced, going back in a 2nd or 3rd time for a high volume pump brings it up enough to be ok with it.


if you have a walking cam bearing. I'm pretty sure you can't change them in the truck. you need to pull the engine.

Click to expand...

No the mechanical guage and dash are pretty much the same at this point. Hot idle goes down to the top of the red after driving it 10 miles or so.

Yeah im not really looking to throw good money and labor after bad. Im am totally primed to not play around and build a new one from scratch. That way I know I have a machinist that knows what he's doing. Everything can be mic'd mixed and matched, and triple checked. I've built enough motors im sure I can do it I just dont want to the the R&R.

This thing is in really good shape and my wife loves it so......

SpareParts said:

If I remember right, I have read that the Aluminum blocks almost never have a #3 cam bearing walk and it's mostly an iron block problem. The #3 cam bearing simply does not have enough contact area to properly support the cam. You can buy longer bearings and also oversize OD bearings.
You can not change the cam bearings in the truck and the engine will need pulled but you can change the bearings with the crank and rods installed.
My engine is a 2007, L92. Flat valley cover and has VVT. When i got it the oil pressure was 10PSI hot or slightly less if I remember right. I also had shiny bits in the oil when I changed it.
I installed a Milling HV oil pump and new O ring. After replacing it the hot oil pressure is 23ish PSI after driving for an hour at freeway speed for a few months now. Maybe I caught it in time?
I have also read the DOD valley cover can leak pressure from the 8, O rings leaking under the cover.

Click to expand...

Yeah thats the only thing I havnt checked but man those valley cover O-rings would have to be gushing to do what this thing is doing. It doesn't look like much to pull the intake from videos I have seen, but man I'm too old to be chasing shit like this around forever......and how could I definitively know that was the issue? Id have to change it out and cross m fingers. if it was that, I still have the DOD style lifters and all that crap in there.

Im 63YO. I sometimes feel like I'm getting too old for this shit also, But after I thought about it a few months ago, I realized I like it and enjoy it as long as it's on my schedule and not someone else's.

donjetman said:

This will keep ya busy:
https://www.onallcylinders.com/2019...de-to-ls-engine-specs-and-ls-engine-upgrades/

Click to expand...

Yeah it will if I end up building from scratch........I am nerding out on this a bit cuz all this LS stuff is new to me.

You can plug the oil pressure relief in the pan when deleting the AFM. It's there to protect the AFM solenoids in case your pressure spikes more than 65 PSI. (Which damages the solenoids)

Those o-rings into the valley cover.... Not only are they problematic for losing oil pressure, it's not unusual to find the valley cover bolts themselves very loose. I'm talking finger tight even. Expect about 20 to 25 minutes to pull the intake the first time. After you get used to it it's only a 10 minute job to pull it. I'm 61, and the hardest part about it is simply leaning over a short stool to stand on and a body pillow to lay over the fender, or above the radiator.

It is a bit of a conundrum with the metal shavings they were in the pan. At my current age, I'm being kind to just pull the motor and go through it so I don't have to deal with it in 5 years when it will be 10 times more difficult physically. And I find it easier to pull the heads with the engine in the car, and then pull the engine. Makes getting to the upper bell housing bolts so much easier. And then I put the heads on after the blocks installed. And it's worth the money to get the ARP head bolts. Just torque them down the way you always have. The torque to yield stretch bolts with an angle gauge, a real pia in the car. (i.e: if you have to turn a bolt another 60°, and there's not room.... Your left turning it 30° twice. And you'll always be left wondering about them.)

rdezs said:

One more note. Anytime you change the camshaft or crankshaft position sensor, and sometimes when replacing the timing chain, a relearn is necessary.

Click to expand...

@ckeister
at 196k miles
for preventative maintenance
I changed my cam position sensor recently. Did NOT need a relearn.
replaced valley cover, bolts were NOT loose.
https://www.tahoeyukonforum.com/threads/valley-cover-crank-pulley-etc.149036/

ckeister said:

No the mechanical guage and dash are pretty much the same at this point. Hot idle goes down to the top of the red after driving it 10 miles or so.

Yeah im not really looking to throw good money and labor after bad. Im am totally primed to not play around and build a new one from scratch. That way I know I have a machinist that knows what he's doing. Everything can be mic'd mixed and matched, and triple checked. I've built enough motors im sure I can do it I just dont want to the the R&R.

This thing is in really good shape and my wife loves it so......

Click to expand...

huh. yeah, that sounds low enough it's worth fixing then.

so all I can add is my experience with the afm oil holes under the vlom. those leaking will absolutely not be your problem, unless the lifter bores are worn much larger than they should be. my afm disable kit has you make sure to cut those gaskets in half to make sure even if the solenoids fail to vent the oil pressure, the pressure can't activate the afm lifter. I did mine and saw zero difference in oil pressure. it's designed to vent any time afm isn't active. if you plug those holes with the afm lifters in it, with say a smooth non afm cover. it will run about a minute before a lifter sticks. a guy here did it. without a lifter bore issue, or installing non afm lifters, they need to be open.


I honestly got nothing but as a hail mary you could try the variable displacement oil pump used on the hybrids. I've seen the corvette guys talk about them since they save a few hp. they have a much much higher minimum spec and mine never seen a under 50psi hot idle.

oil pressure spec hot
36psi @1000
42psi @2000
45psi @4000
afm relief valve 55-75 max.
p0521 ecm detecta different oil pressure than expected by lower 6.8psi or greater than 7.3 psi for 10sec

I think millings makes it for gm. part number 12623423.

total bandaid and it's not a easy change, but at this point. unless you can figure out why it had better pressure for a little bit. next would be pulling the engine for a rebuild and seeing where all that oil could be going. if you can get 10 psi hot idle, even with thicker oil. I'd drive it till it fails lol. but I'm old and hate working on stuff outside of work anymore.