DOD delete but keep VVT?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

rdezs

Full Access Member
Joined
Nov 6, 2023
Posts
1,230
Reaction score
2,183
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.
 
OP
OP
C

ckeister

Member
Joined
Jan 13, 2025
Posts
64
Reaction score
60
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.
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.
 

SpareParts

Supporting Member
Joined
Sep 17, 2023
Posts
1,578
Reaction score
3,463
Location
North Idaho
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.
 
OP
OP
C

ckeister

Member
Joined
Jan 13, 2025
Posts
64
Reaction score
60
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.
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......
 
OP
OP
C

ckeister

Member
Joined
Jan 13, 2025
Posts
64
Reaction score
60
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.
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.
 

SpareParts

Supporting Member
Joined
Sep 17, 2023
Posts
1,578
Reaction score
3,463
Location
North Idaho
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.
 

rdezs

Full Access Member
Joined
Nov 6, 2023
Posts
1,230
Reaction score
2,183
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.)
 

donjetman

Full Access Member
Joined
Oct 22, 2018
Posts
1,951
Reaction score
3,547

j91z28d1

Full Access Member
Joined
Feb 28, 2022
Posts
4,545
Reaction score
5,790
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......


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.
 
Joined
Aug 30, 2018
Posts
83
Reaction score
60
Location
Los Angeles, CA
So here's how it has gone since purchase. After I noticed the oil pressure situation I did an immediate oil change with Amsoil 5-30 and Amsoil filter. Got a slight improvement. Didn't cut open the filter like a dummy. Put about 5K than another oil change. Stayed pretty consistent and like I said no alarms have gone off in the dash. Factory specs say idle oil pressure can be as low as 6 PSI which I think is ******** but.....

While doing routine stuff like changing belts hoses tentioners, fluid changes, etc. I found an old screen that goes under the pressure sender stuck between some shit in the engine compartment where someone dropped it so knew the sender had been changed at least once.

About this time last year, I broke my ankle real bad and was laid up for 12 weeks with another 12 weeks of PT. During that time, the ignition switch took a shit so I sent it to a mechanic and told him about the pressure issue. He changed the pressure switch again (put in a NAPA unit) and told me it was the o-ring and when you do that job ou just do the pump at the same time quoted me $2500. I asked him if he put a mechanical guage in to test actual pressure, nope just guessed and changed parts. Ok I'll pass and wait until I recover to do it myself, thanks.

Another 5K on the clock so went to do the job. Put a mechanical guage on the port comming off the oil pump. Never went below 37 PSI at the pump (Take note cuz this is the beginning of my head scratching) but had a consistent 15 PSI difference through out the RPM band. First big red flag.

Pulled the pan and has some metal shavings but nothing that was super obvious or concerning. Pulled a couple rod bearings, they looked good. Did a visual of the cam bearings and there was no obvious walk out on them. Should of cut the oil filter open I know but was wanting to get the job done. Replaced the pick up tube and O-ring with a Melling unit. The o-ring was **** eyed a little on the tube and flattened out a bit but not split. Slapped it back together, filled it up and ran it again.

Now here is where things start getting wierd. Picked up about 10 PSI on the cold start and about had a more consistent reading between the mechanical guage and the dash and hot idle went from 6-8 lbs up to 15-18lbs. Now the mechanical guage and dash were reading the same. What happened to my 37 lbs out of the pump at idle? Stuck relief valve in the pump im thinking.

Since I hadn't put the front differential back in, I went ahead and ordered a melling 365HV. Timing chain is nice and tight but while im here I said screw it and replaced the cam plate, VVT solenoid, timing chain tentioner, and couple other things that I know are prone to go out and much easier to change with the front diff out.

Back together it goes, and no improvement. In fact the 15 lbs of pressure variance came back abouve 2500 RPM but not improvement at idle 15-18. Additionally I have an intermittent fluttering on both guages (2nd big red flag)

Wife drives it to the store an back, maybe 20 miles round trip. Comes back and says the guage in the dash is back down to just above the red mark which was where it sat when it was running 6-8lbs. All that work FML....lol

So we go for a nice evening drive and put about 50 miles on it. The entire time I had at least 10LBS per 1000RPM throughout the the RPM range.....for the first part of the trip. On the way back home pressure keeps getting slightly worse,do a couple of hard accelerations and loose that 10 lbs per 1000 RPM at 3500-4000 RPM (Third big red flag).

Going up the mountain almost home and it starts losing power, less oil pressure to the point I get a check engine light 5 minutes from home. Once home and idling pressure is lower than ever even appearing to slightly go into the red, but again no dash warning. Plug the code reader and get p0011. Damn it.

Cleared the code and drove it around the next day about 10-15 miles code hasnt come back. I'm confident I didn't F anything up with the timing. Marks all lined up fine. I don't thing its the O-ring because I pulled the dipstick and no air bubbles on the stick.

So here is where I stand. I think either I have smoked cam bearing or one beginning to walk out or both. Only thing that makes sense in my head. No lifter noise, seems to run fine, and no misfire codes have popped up.
been there Man, i'm in California as well I rebuilt my engine as well eliminated DOD but kept VVT. if you have any questions let me know. my smog is due in a month so we will see if it will pass.
 

MrMonte

Full Access Member
Joined
Jun 23, 2022
Posts
281
Reaction score
739
I deleted my AFM/DOD 40k miles ago but kept the VVT on my 2018 Yukon Denali 6.2L/10 speed. Unless you are going with a big cam VVT will give you better performance thru the rpm range.

I have more power from idle to redline, quicker throttle response and better gas mileage. Never see a tank below 20mpg.
 

Forum statistics

Threads
138,058
Posts
1,974,767
Members
102,294
Latest member
Rene123

Latest posts

Back
Top