2012 Yukon XL - 6.2L Engine Rebuild/Swap & Addressing AFM/DOD

[Campbesl]

Dave / Geotrash,

Thank you for the awesome amount of information that you have posted on the DOD/VVT delete. I have been reviewing your Oct 2021 post where you did the DOD/VVT delete with a Cam Motion cam. I compared it to your Oct 2023 post where you listed the parts for a DOD delete (retains VVT) with a GM L9H cam.

My 2012 Yukon Denali XL 6.2 liter has 205K miles. It's running good but definitely ticks on start up. I have a OBDII plug to turn off AFM but fear that its just a matter of time before the engine craps out from AFM failure. I'm working hard to research AFM delete and REALLY appreciate the parts list that you posted above. Doing it while retaining VVT seems to simplify the project. I have a couple of questions that I hope you can answer.

- At 205K miles, is it reasonable to assume that my rocker arms and valve springs are still good or should I budget replacement of those parts? I will have a machine shop perform a head refresh.

- With the L9H cam (P/N 12711967) and Chevrolet Performance lifters (P/N 12499255) will the original push rods work or will a length change be required? I assume the later since you suggested to only buy a couple of push rods in case a few are bent. I'm just seeking confirmation on this.

- The timing cover seal alignment tool that you linked on Amazon is no longer available. Would this work as a substitute? AMAZON SEAL TOOL.

- Is it not possible to remove the hood latch blade? I see your comment to pad it with a pool noodle but I'm amazed that it is not removable. Can you please confirm this?

Okay, this is the first round of questions. Your parts list(s) and your notes seem to be immensely helpful. THANK YOU!!!

Best regards,

Scott

 

[rdezs]

Robert here, throwing my two cents in as I did our 2014 Escalade last year.

At 200,000+, I would go ahead and use new push rods and upgrade the trunions with a new bearing kit. Your valve springs are probably just fine, when they go through the head they will check. You will want to get a pushrod length checker and they micrometer and select the correct size push rods. It does all very based on how much they take off the head flattening it, the head gasket, the wear on the rocker tips, etc

The question will be the front camshaft bearing. It's normal to see some wear there.... Just how much depends on how well the vehicle is maintained with oil changes.

Chevrolet performance lifters are just fine....

That's the correct alignment tool for the front cover and the rear main.

Hood latch.... A body pillow over it works well. I'm sure it comes out though. Easier to just cover it up with some padding to avoid scars across your abdomen, lol.

I would recommending getting a tuner to turn off the AFM so you don't have to rely on that plug-in OBD2 thing. I use the Diablo sport predator, was simple enough and you can adjust some other settings as well like tightening up the shifts to extend transmission life.

 

[Fless]

Dave / Geotrash,

Thank you for the awesome amount of information that you have posted on the DOD/VVT delete. I have been reviewing your Oct 2021 post where you did the DOD/VVT delete with a Cam Motion cam. I compared it to your Oct 2023 post where you listed the parts for a DOD delete (retains VVT) with a GM L9H cam.

My 2012 Yukon Denali XL 6.2 liter has 205K miles. It's running good but definitely ticks on start up. I have a OBDII plug to turn off AFM but fear that its just a matter of time before the engine craps out from AFM failure. I'm working hard to research AFM delete and REALLY appreciate the parts list that you posted above. Doing it while retaining VVT seems to simplify the project. I have a couple of questions that I hope you can answer.

- At 205K miles, is it reasonable to assume that my rocker arms and valve springs are still good or should I budget replacement of those parts? I will have a machine shop perform a head refresh.

- With the L9H cam (P/N 12711967) and Chevrolet Performance lifters (P/N 12499255) will the original push rods work or will a length change be required? I assume the later since you suggested to only buy a couple of push rods in case a few are bent. I'm just seeking confirmation on this.

- The timing cover seal alignment tool that you linked on Amazon is no longer available. Would this work as a substitute? AMAZON SEAL TOOL.

- Is it not possible to remove the hood latch blade? I see your comment to pad it with a pool noodle but I'm amazed that it is not removable. Can you please confirm this?

Okay, this is the first round of questions. Your parts list(s) and your notes seem to be immensely helpful. THANK YOU!!!

Best regards,

Scott

Let's tag @Geotrash so we're sure he sees it.

 

[Geotrash]

Dave / Geotrash,

Thank you for the awesome amount of information that you have posted on the DOD/VVT delete. I have been reviewing your Oct 2021 post where you did the DOD/VVT delete with a Cam Motion cam. I compared it to your Oct 2023 post where you listed the parts for a DOD delete (retains VVT) with a GM L9H cam.

Hi Scott, I'm glad you found my posts helpful.

My 2012 Yukon Denali XL 6.2 liter has 205K miles. It's running good but definitely ticks on start up. I have a OBDII plug to turn off AFM but fear that its just a matter of time before the engine craps out from AFM failure. I'm working hard to research AFM delete and REALLY appreciate the parts list that you posted above. Doing it while retaining VVT seems to simplify the project. I have a couple of questions that I hope you can answer.

Using the L9H cam does simplify the project in terms of tuning. All you'll need to do in a tune is turn off AFM. But it also means removing the starter so you can put a holding tool against the flywheel teeth while you torque the cam bolt. And of course you lose out on the performance of a larger cam. I'm still very happy with the Cam Motion cam I chose and don't miss the VVT at all. The Blackbear tune is working out great as well.

- At 205K miles, is it reasonable to assume that my rocker arms and valve springs are still good or should I budget replacement of those parts? I will have a machine shop perform a head refresh.

The rocker arms on these engines are very durable. The examples people on the web often cite of puking needle bearings were primarily limited to the LS1 engines. I've never seen an example of someone with stock or near-stock cams having a problem with the factory rockers on a Gen3 or Gen4 LS engine. That's not true for the valve springs, however. Lots of guys here have had a valve spring fail on the 6.2's. We've also seen examples of 6.2's dropping valve seats, so I would recommend having the heads cleaned up by a machine shop and the valve seats checked. New springs and valve stem seals are a must, in my opinion. Replacing the rockers is optional but if I had to do it again, I would either just keep my original rockers, or buy new GM rockers if I needed more peace-of-mind and not bother with the trunnion kit.

- With the L9H cam (P/N 12711967) and Chevrolet Performance lifters (P/N 12499255) will the original push rods work or will a length change be required? I assume the later since you suggested to only buy a couple of push rods in case a few are bent. I'm just seeking confirmation on this.

The factory length pushrods on nearly all Gen4 engines is 7.400", including on the AFM cylinders. But they're cheap, so you might as well replace them while you're in there, unless you're on a tight budget - in which case I'm sure the originals will be fine if they roll true across a tabletop. If you go with a bigger cam as I have, upgraded chromoly pushrods are a wise investment.

- The timing cover seal alignment tool that you linked on Amazon is no longer available. Would this work as a substitute? AMAZON SEAL TOOL.

Yes, that one will work fine.

- Is it not possible to remove the hood latch blade? I see your comment to pad it with a pool noodle but I'm amazed that it is not removable. Can you please confirm this?

It's possible, but not necessary at all. The pool noodle (or just an old t-shirt wrapped around it) renders it a non-issue.

Okay, this is the first round of questions. Your parts list(s) and your notes seem to be immensely helpful. THANK YOU!!!

Best regards,

Scott

Good luck!

 

[Geotrash]

I'll just add one more thing here that I've learned on various engine forums and forgot to mention: Aluminum heads will experience metallurgical changes over time in normal use. The aluminum gets softer with continued exposure to the heat of combustion, and fatigue cycles accumulate as the engine warms up and cools down. This is partly why an engine run for 100+ miles every day will go more miles than one that only goes a handful of miles every day. Thermal cycles matter. The best solution for aluminum heads is to simply buy new ones and reset the clock, but that's not always realistic, depending on one's budget.

 

[rdezs]

I look at the aluminum blocks the same way. While I wouldn't hesitate to rebuild one with 200,000 miles to OEM specs.... I would not rebuild it with the goal of making serious power. I've seen a couple aluminum 6.2 blocks that probably did not have good maintenance, that had excessive wear in the lifter bores. Kind of strange, I don't recall ever seeing anything on a forum where someone's talking about doing a rebuild... where they checked their lifter bores..... I know Melling had an article about it a year or two ago. Explaining lifter failures in recently rebuilt motors if I remember right.