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

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smiley91

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Apologies in advance for yet another AFM/DOD post to muddy the forum waters, but I have the 6.2L with 180k. It has a collapsed lifter and low oil pressure (leaking from oil pump). It may be conjecture for me to assume that it is AFM related, but I do hear that this type of problem is a common symptom of how the AFM functions. It looks like my best option is to put a remanufactured engine in it. I could try the rebuilding route, but there is no guarantee that there aren't other internal issues happening on outside of lifters and oil pump, so I don't want it to end up being a money sink when just swapping could be less headache (but I am open to ideas if you all disagree with this mentality). I have called a couple of places, getting a feel for how they do the swap, and I brought up the AFM point. Multiple places are recommending just to swap it with a crate 6.2L engine from GM directly that will come with a 3-year/100k warranty.

Challenge is, if I have them put a delete kit on it, it will likely void the warranty from GM. If this is a reused block with all new internal components (lifters, rockers, cam, rods, etc), would just tuning out the AFM be good enough in this instance? I know that the parts will still be for AFM, but is it worth the extra cost at this point to mechanically delete it?
 

Dustin Jackson

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@smiley91 With 180k I think you're well past any GM warranty out there.

If you can get the motor properly diagnosed then rebuilding it has little to no risks, it's when people make assumptions and apply a "fix" to the problem without actually identifying the problem.

There should be shops out there that have experience with this type of things, any shop that jumps straight to replacing the motor isn't interested in properly fixing the problem.
 

swathdiver

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Apologies in advance for yet another AFM/DOD post to muddy the forum waters, but I have the 6.2L with 180k. It has a collapsed lifter and low oil pressure (leaking from oil pump). It may be conjecture for me to assume that it is AFM related, but I do hear that this type of problem is a common symptom of how the AFM functions. It looks like my best option is to put a remanufactured engine in it. I could try the rebuilding route, but there is no guarantee that there aren't other internal issues happening on outside of lifters and oil pump, so I don't want it to end up being a money sink when just swapping could be less headache (but I am open to ideas if you all disagree with this mentality). I have called a couple of places, getting a feel for how they do the swap, and I brought up the AFM point. Multiple places are recommending just to swap it with a crate 6.2L engine from GM directly that will come with a 3-year/100k warranty.

Challenge is, if I have them put a delete kit on it, it will likely void the warranty from GM. If this is a reused block with all new internal components (lifters, rockers, cam, rods, etc), would just tuning out the AFM be good enough in this instance? I know that the parts will still be for AFM, but is it worth the extra cost at this point to mechanically delete it?
Any GM dealership will not delete AFM or even disable it. Not allowed to.

I'm curious about where the oil pump is leaking from, don't hear about that much.

It's in most shop's best interests to just swap out one engine for another, saves them time and most don't have the expertise for rebuilding anyways. A performance shop does.

When an engine is disassembled for rebuilding, the block and heads go through testing to make sure that they are serviceable and without cracks in them. Then measurements are taken of the cylinder, camshaft journals, connecting rods, crankshafts to see if any can be used again and if any minor machining is required along with what size bearings will be used during the rebuild.

You basically want to convert your L94 into an L9H or convert a crate LS3 into an L9H. Have you actually seen any GM 6.2 crate engines recently? They've been eluding me!
 

Geotrash

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I have a 2012 XL Denali as well and did a cam swap including oil pump in my garage. Got some bad lifter trays from an aftermarket vendor and ended up doing the job 3x until I figured it out. But now it’ll outrun pert near anything else’s in its weight class.

Are you handy, have some tools and comfortable working on this truck? If so, we’ll get you through the job and you’ll spend about $1500 in parts. If not, a Jasper L9H will run you $8K installed but is basically an L94 without AFM.

180K is nothing on the bottom end on these if they’ve been maintained well and run on premium fuel. If I were in your shoes, I’d tear into that thing and put a new cam, lifters, pushrods and oil pump in it. It’ll take you 1-2 weekends and it’ll feel good when you’re done.
 

Wander

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I have a 2012 XL Denali as well and did a cam swap including oil pump in my garage. Got some bad lifter trays from an aftermarket vendor and ended up doing the job 3x until I figured it out. But now it’ll outrun pert near anything else’s in its weight class.

Are you handy, have some tools and comfortable working on this truck? If so, we’ll get you through the job and you’ll spend about $1500 in parts. If not, a Jasper L9H will run you $8K installed but is basically an L94 without AFM.

180K is nothing on the bottom end on these if they’ve been maintained well and run on premium fuel. If I were in your shoes, I’d tear into that thing and put a new cam, lifters, pushrods and oil pump in it. It’ll take you 1-2 weekends and it’ll feel good when you’re done.
I have just run into the lifter failure problem on a "new to us" 2012 Yukon XL Denali. It's at 170k and calling a couple places puts the repair bill out of range for us. And I've been watching some videos and it looks like something I can do. Now I'm trying to figure out the right kit/parts.

This is my wife's daily driver and we pull a trailer a few times a year but other than that I'm not worried about increasing performance, getting it running again and reliability is the focus.

There is one from AMS racing that looked about right, but I'm not far enough in to know what the lifter options mean. Is there a canned kit I can get that has everything I would need?
 

Geotrash

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I have just run into the lifter failure problem on a "new to us" 2012 Yukon XL Denali. It's at 170k and calling a couple places puts the repair bill out of range for us. And I've been watching some videos and it looks like something I can do. Now I'm trying to figure out the right kit/parts.

This is my wife's daily driver and we pull a trailer a few times a year but other than that I'm not worried about increasing performance, getting it running again and reliability is the focus.

There is one from AMS racing that looked about right, but I'm not far enough in to know what the lifter options mean. Is there a canned kit I can get that has everything I would need?
Texas speed and performance sells pre-packaged DoD delete kits that include much of what you need. But, you can also get a factory cam from the L92 or L9H - both are Gen IV 6.2L without AFM but they retain VVT. The L9H cam plus Chevrolet Performance LS7 lifters and GM lifter trays would make a great core of an inexpensive cam swap project and you can keep all of the stock rockers and springs. Here is a complete parts list for you if you want to roll your own:


Special tools to have on hand before you start:
Hope this is helpful. Let us know if you decide to tackle the project and good luck! Here are my notes from when I did mine:

 
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Wander

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Texas speed and performance sells pre-packaged DoD delete kits that include much of what you need. But, you can also get a factory cam from the L92 or L9H - both are Gen IV 6.2L without AFM but they retain VVT. The L9H cam plus Chevrolet Performance LS7 lifters and GM lifter trays would make a great core of an inexpensive cam swap project and you can keep all of the stock rockers and springs. Here is a complete parts list for you if you want to roll your own:


Special tools to have on hand before you start:
Hope this is helpful. Let us know if you decide to tackle the project and good luck! Here are my notes from when I did mine:

Thank you, this is perfect! I'll look through everything and start ordering soon.
 

rdezs

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Pay attention to which camshaft they package when looking for the AFM DOD delete for the 6.2 on their website. It will likely only offer you the lower lift camshaft that came on the 6.0. You will obviously lose some horsepower on that. The correct camshaft is from the l9h engine as detailed in the list above in the previous post. That is assuming you want to keep it basically stock and just not have the AFM DOD and retain the variable valve timing.
 

petethepug

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Door #3 is slapping in an L96 6.0L 360/380 hp/tq from a 3/4 or 1T truck. No DOD/AFM, e85, iron block, aluminum heads runs on Reg gas and turn key install. You’ll just need a tune to turn off the AFM in your existing ECM. Do a cam swap if you want the full 400hp back of the 6.2L.


I finally got this done a couple weeks ago. Thanks to everyone here for your input, especially Swathdiver. Your assessment was spot on. This was plug and play with the tune, runs great on regular gas. I think we're going to go back into the tune a little, we just used the stock L96 parameters. Gas mileage is down about 2 MPG, but O2 sensor and fuel trim data look perfect on my Snap on scan tool. I'm thinking that the premium fuel L94 with more aggressive timing may just be a bit more efficient. Anyway, I'm very pleased with the results and the increased bottom end torque is noticeable.
 
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Pay attention to which camshaft they package when looking for the AFM DOD delete for the 6.2 on their website. It will likely only offer you the lower lift camshaft that came on the 6.0. You will obviously lose some horsepower on that. The correct camshaft is from the l9h engine as detailed in the list above in the previous post. That is assuming you want to keep it basically stock and just not have the AFM DOD and retain the variable valve timing.
when I was checking this site last the packages offered the cam that's identical to an LS7 cam. When I posted about it many asked if I was turbo charging my engine, which I was not. If you don't care for a special cam Check rock auto for an L92 cam or an L9H cam and buy it separately. just did this and started the dismantling of my engine.
 

Campbesl

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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

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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

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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

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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!
 
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Geotrash

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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

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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.
 

Fless

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Dress,

Does the Cam Motion stage 2 Cam that Geotrash used in his build qualify as 'serious power?

Who is "Dress?"

Tip: if you want to tag someone, either "reply" to that member's post (like I did here with yours) or 'tag' him using the "@" symbol and start typing the member's name. A picklist will come up and you can select the name from that. If you don't use the reply or tag function the member may not see your post.
 

Geotrash

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Dress,

Does the Cam Motion stage 2 Cam that Geotrash used in his build qualify as 'serious power?
In my opinion, serious power will only come with a supercharger or other forced induction setup. But the cam motion cam does provide a significant enhancement in overall performance, in my opinion. It’s a great match for the power needs of a 3 ton SUV.
 

Campbesl

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Who is "Dress?"

Tip: if you want to tag someone, either "reply" to that member's post (like I did here with yours) or 'tag' him using the "@" symbol and start typing the member's name. A picklist will come up and you can select the name from that. If you don't use the reply or tag function the member may not see your post.
Dress = spell check's version of rdezs

And thank you @Geotrash for the tips.
 
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