2012 Yukon Denali - 6.2 lifter or something else? [Advice/How to Proceed]

[Pointer 21]

Good morning - Dreading to even start this post as I haven't had to engage this forum with what I think (hope not) is this biggest issue I've had yet:

2012 Yukon AWD Denali 6.2 (Original Owner),
**165k miles w/trans and rear main seal replaced at 152k in 9/2021
Oil Changed every 5k, mainly city driving

At the time of replacing the tranny I had numerous issues to address (really maintenance/suspension); however, there was an oil leak from the rear main seal (at least I thought) at that time in which I figured I'd have the rear main seal replaced while tackling the transmission. (This wasn't the case - I still have a slight leak around the transfer case that wasn't addressed.

Fast forward - 18 months/15k miles, I'm having my oil changed and I'm 2 quarts low per the oil change kid after me quizzing him.....(alarming however, it had been sitting and I had been monitoring it prior, so I didn't freak out).

One day after the oil change (15 city miles and leaving the car wash) I hear something slightly noisy in the motor and lose power at take off. Sounds minor maybe a belt...took a slow drive home. Pop the hood and it sounds more like a rod knock..... It gets louder as you rev the engine. I emphasize the car wash and oil change bc its an odd sequence and prior to popping the hood I'm thinking wet belt something minor HOPEFULLY NOT WATER IN THE OIL....

I parked it and haven't driven it since (so it was only driven 5 miles slowly after the noticeable issue). I realize a Tech 2 (i don't have) and proper diagnosis would help give clarity here but wanted some insight/trouble shooting/info on how to proceed from the gang.....

Any input is much appreciated - I'm charting into territory I did not see coming nor am I well versed in...hoping there's some light at the end of this tunnel.

Thanks!

 

[Geotrash]

Good morning - Dreading to even start this post as I haven't had to engage this forum with what I think (hope not) is this biggest issue I've had yet:

2012 Yukon AWD Denali 6.2 (Original Owner),
**165k miles w/trans and rear main seal replaced at 152k in 9/2021
Oil Changed every 5k, mainly city driving

At the time of replacing the tranny I had numerous issues to address (really maintenance/suspension); however, there was an oil leak from the rear main seal (at least I thought) at that time in which I figured I'd have the rear main seal replaced while tackling the transmission. (This wasn't the case - I still have a slight leak around the transfer case that wasn't addressed.

Fast forward - 18 months/15k miles, I'm having my oil changed and I'm 2 quarts low per the oil change kid after me quizzing him.....(alarming however, it had been sitting and I had been monitoring it prior, so I didn't freak out).

One day after the oil change (15 city miles and leaving the car wash) I hear something slightly noisy in the motor and lose power at take off. Sounds minor maybe a belt...took a slow drive home. Pop the hood and it sounds more like a rod knock..... It gets louder as you rev the engine. I emphasize the car wash and oil change bc its an odd sequence and prior to popping the hood I'm thinking wet belt something minor HOPEFULLY NOT WATER IN THE OIL....

I parked it and haven't driven it since (so it was only driven 5 miles slowly after the noticeable issue). I realize a Tech 2 (i don't have) and proper diagnosis would help give clarity here but wanted some insight/trouble shooting/info on how to proceed from the gang.....

Any input is much appreciated - I'm charting into territory I did not see coming nor am I well versed in...hoping there's some light at the end of this tunnel.

Thanks!

Best thing to do is record a video with your mobile phone of the noise, upload it to YouTube with public permissions and link it back here. We'll give it a listen and go from there.

Also, is it safe to assume that you checked the oil after this and it's still topped up? A stuck or damaged lifter can sound like a rod knock but a rod knock is at the same frequency as crankshaft rotation, and a lifter tick (or exhaust manifold leak) are at a frequency of half crank rotation speed (slower).

 

[swathdiver]

To start with check your oil level first and look at the condition of the engine oil cooler lines going into the radiator on driver's side. Weeping is ok, leaking is not.

If those check out, get something you can use as a stethoscope, like a long extension. Fire up the motor and let it idle and look for the source of the sound. Believe it or not, an exhaust leak can sound like a rod knock, had it happen to me. Happened when the kids spilled too much oil filling it up and then started the engine with all that oil on the manifold. Oil change place or car wash place "might" have done the same thing. And do what Dave says!

 

[Pointer 21]

Best thing to do is record a video with your mobile phone of the noise, upload it to YouTube with public permissions and link it back here. We'll give it a listen and go from there.

Also, is it safe to assume that you checked the oil after this and it's still topped up? A stuck or damaged lifter can sound like a rod knock but a rod knock is at the same frequency as crankshaft rotation, and a lifter tick (or exhaust manifold leak) are at a frequency of half crank rotation speed (slower).

To start with check your oil level first and look at the condition of the engine oil cooler lines going into the radiator on driver's side. Weeping is ok, leaking is not.

If those check out, get something you can use as a stethoscope, like a long extension. Fire up the motor and let it idle and look for the source of the sound. Believe it or not, an exhaust leak can sound like a rod knock, had it happen to me. Happened when the kids spilled too much oil filling it up and then started the engine with all that oil on the manifold. Oil change place or car wash place "might" have done the same thing. And do what Dave says!

WELP - It got very interesting. I checked the oil and cooler lines (these arent in great shape as I did have a bit of oil on my hands inspecting them). Sent a video to a mechanically inclined buddy who said "that my friend is a rod knock OR LIFTERS"...told me to check the oil and see where it's at (His synopsis was the Oil change place caused this).

I went to check the oil again...issue STOPPED. Ok great....drive around the block (engine light, stabilizer off, traction control off) THIS HAS NEVER HAPPENED BEFORE.

Things to consider - I did a 2.5 level, with a 1.5 block in the back.......It's been running like a dream.

WRONG OIL FILTER? Extended lines from the "2.5 level"?? No clue...I guess a tow into the shop is the best option.

ALL that considered....I have a trust worthy regular ole, mechanic with a nice shop...not necessarily a GM guy, can he tell me his thoughts OR should I go GM specific? My thought is that IF this is the worst case scenario, I'll be Deleting the AFM, chipping, etc...what to do, what to do???

 

[Geotrash]

WELP - It got very interesting. I checked the oil and cooler lines (these arent in great shape as I did have a bit of oil on my hands inspecting them). Sent a video to a mechanically inclined buddy who said "that my friend is a rod knock OR LIFTERS"...told me to check the oil and see where it's at (His synopsis was the Oil change place caused this).

I went to check the oil again...issue STOPPED. Ok great....drive around the block (engine light, stabilizer off, traction control off) THIS HAS NEVER HAPPENED BEFORE.

Things to consider - I did a 2.5 level, with a 1.5 block in the back.......It's been running like a dream.

WRONG OIL FILTER? Extended lines from the "2.5 level"?? No clue...I guess a tow into the shop is the best option.

ALL that considered....I have a trust worthy regular ole, mechanic with a nice shop...not necessarily a GM guy, can he tell me his thoughts OR should I go GM specific? My thought is that IF this is the worst case scenario, I'll be Deleting the AFM, chipping, etc...what to do, what to do???

Thanks for the update. Just to make sure I understand, when you say stopped, do you mean that the knocking sound went away along with all the indications, or did you mean that the engine stopped? And was the oil level okay?

If the sound went away and the oil level was okay, I would be inclined to just drive it. It’s not unheard of for a lifter to get stuck for a while and start functioning properly again… assuming that’s what it was. We don’t know because we still don’t have a video.

My hypothesis is that assuming the oil level was fine, that the sound went away and that if a lifter was indeed the problem (most likely), that a lifter stuck in the cylinder deactivate position for a while and then unstuck itself. If so, I would have the AFM system tuned out as soon as possible - either programmatically or with a Range device.

The leveling kit had nothing to do with it. And in my experience, most any shop has experience with these engines and problems now. They’re one of the most common powertrains on the road.

 

[Pointer 21]

To clarify - The “knocking” happened late Saturday (last weekend). There was no check engine light and it was uneventful until I popped the hood and started connecting the dots. Yesterday (after this post) I checked the oil which was OK, looked under the vehicle which had leaking oil around the filter and was chalking it up to a lifter issue. Moved the vehicle to level ground to check the oil again and the noise is GONE! I’m thinking I’m being warned here and yes - delete ASAP. I drive about a 1/4 mile and the traction control, engine light, etc all kicks on (this hadn’t happened yet). I was nervous about driving it home and was going to have it towed about 1 mile from where I stopped to my house (I ended up driving it back) - hope I didn’t cause more damage here.

Anyhow - I’ve got a check engine light (which even auto zones deal can read that code). Obviously a lot of variables here but if this does end up being the worst case scenario I’d imagine I’d want to do a lot of “while you’re in there work” including addressing the issues and future issues which is why I want to get to a shop that will work with me (would that be a performance shop)?

Any tips and/or if the “while you’re in there” is applicable and/or advisable or if I’m over thinking it is much appreciated.

If I need to cut bait and run - please lay that on me too! I’m not a happy camper with this costly vehicle right now….

 

[Geotrash]

To clarify - The “knocking” happened late Saturday (last weekend). There was no check engine light and it was uneventful until I popped the hood and started connecting the dots. Yesterday (after this post) I checked the oil which was OK, looked under the vehicle which had leaking oil around the filter and was chalking it up to a lifter issue. Moved the vehicle to level ground to check the oil again and the noise is GONE! I’m thinking I’m being warned here and yes - delete ASAP. I drive about a 1/4 mile and the traction control, engine light, etc all kicks on (this hadn’t happened yet). I was nervous about driving it home and was going to have it towed about 1 mile from where I stopped to my house (I ended up driving it back) - hope I didn’t cause more damage here.

Anyhow - I’ve got a check engine light (which even auto zones deal can read that code). Obviously a lot of variables here but if this does end up being the worst case scenario I’d imagine I’d want to do a lot of “while you’re in there work” including addressing the issues and future issues which is why I want to get to a shop that will work with me (would that be a performance shop)?

Any tips and/or if the “while you’re in there” is applicable and/or advisable or if I’m over thinking it is much appreciated.

If I need to cut bait and run - please lay that on me too! I’m not a happy camper with this costly vehicle right now….

Thanks for clarifying. I get it - you rely on this vehicle, don't yet know what you're up against, and without more certainty you don't want to make things worse.

Yes, I think you have received a warning from the AFM system that it's time to take some sort of action (sure would appreciate a copy of that video to be certain - happy to PM you my mobile # if you don't want to upload to YouTube). But at any rate, here would be my courses of action if I were in your shoes. (Understanding also that I have done a mechanical AFM delete on my 2012 XL Denali in my garage so I know first-hand what that entails).

1/ Electronically disabling the AFM system - either through a tune or with a Range device will make your valvetrain as reliable as a regular non-AFM valvetrain. I would prefer a tune for this to make the change permanent. There are a few ways to go for this; a) a tune from @BlackBearPerf will do many things, including wake up the performance of your engine and transmission without sacrificing reliability or durability for about $700. Or b) send your ECM out to a guy that @iamdub knows about and have AFM turned off for about $50. Or c) Buy a tuner like Diablo Sport or HP Tuners and learn to do it all yourself.

2/ Mechanically deleting the AFM system - this will cost anywhere from $2500 - $5000 depending on how deep you go, but you can get a bigger cam to boost performance if you wish or stay with a factory cam profile but either way the cam will have to come out. New lifters, valve stem seals, etc etc.

Personally, if I had this to do all over again, I would just disable the AFM system with a Black Bear Tune and party on. But if you're looking for self-torture and feel like tackling this yourself, here is my story to help guide you:

2012 Yukon XL Denali 6.2L Cam Swap Thread

I love that Cam Motion measures each cam after grinding and finishing. Here's the cam card. Blub blub blub...

www.tahoeyukonforum.com

 

[Pointer 21]

Thanks for clarifying. I get it - you rely on this vehicle, don't yet know what you're up against, and without more certainty you don't want to make things worse.

Yes, I think you have received a warning from the AFM system that it's time to take some sort of action (sure would appreciate a copy of that video to be certain - happy to PM you my mobile # if you don't want to upload to YouTube). But at any rate, here would be my courses of action if I were in your shoes. (Understanding also that I have done a mechanical AFM delete on my 2012 XL Denali in my garage so I know first-hand what that entails).

1/ Electronically disabling the AFM system - either through a tune or with a Range device will make your valvetrain as reliable as a regular non-AFM valvetrain. I would prefer a tune for this to make the change permanent. There are a few ways to go for this; a) a tune from @BlackBearPerf will do many things, including wake up the performance of your engine and transmission without sacrificing reliability or durability for about $700. Or b) send your ECM out to a guy that @iamdub knows about and have AFM turned off for about $50. Or c) Buy a tuner like Diablo Sport or HP Tuners and learn to do it all yourself.

2/ Mechanically deleting the AFM system - this will cost anywhere from $2500 - $5000 depending on how deep you go, but you can get a bigger cam to boost performance if you wish or stay with a factory cam profile but either way the cam will have to come out. New lifters, valve stem seals, etc etc.

Personally, if I had this to do all over again, I would just disable the AFM system with a Black Bear Tune and party on. But if you're looking for self-torture and feel like tackling this yourself, here is my story to help guide you:

2012 Yukon XL Denali 6.2L Cam Swap Thread

I love that Cam Motion measures each cam after grinding and finishing. Here's the cam card. Blub blub blub...

www.tahoeyukonforum.com

As always many thanks imparting the vast knowledge. For efficiency I sent you a message but will upload the video to the thread for other members knowledge (pressed for time in trying to figure out YouTube)!!

 

[Pointer 21]

Appears to be a lifter issue......Where and how far to go with this is the question at hand.

 

[Geotrash]

Appears to be a lifter issue......Where and how far to go with this is the question at hand.

100% stuck lifter but doesn't sound to my ear like it's eating the cam yet.

Based on our terrific text exchange it looks like your priority is for it to remain a reliable daily driver and you will pay someone else to do the work. With that, I see three options:

1/ Cheapest: try the Crazed Performance lifter trick and see if you can get the lifter unstuck. If you can, immediately have the AFM tuned out with a $50 mail-your-ECM tune, and drive it like you stole it until the wheels fall off. Probably $150 for the tool and the tune, plus your time. If you can find a shop to try the Crazed Performance trick for you, all the better. Probably $500 in labor to give it a try.

2/ Next cheapest: Have a shop identify which lifter failed and replace it along with the lifter trays on that bank. Requires pulling one cylinder head. Probably $1500 in parts and labor.

3/ Fancy: Have a shop install a DoD delete kit from Texas Speed or do like I did and roll your own from the parts you want. This will include a new cam (mild or wild, your choice) and timing set, new lifters and springs, new flat valley pan, new OEM lifter trays and some other doo dads. Probably $3500-$5000 in parts and labor. I would still prefer a Blackbear tune over a local shop, though. Justin knows his shit.

What would I do? Pack a couple of lunches and a cooler of beer, then spend the weekend doing option 3. If I was long on cash and short on time, I would pay a performance shop to do option 3 to my specs.

For a Hail Mary, you can run some marvel mystery oil in there for a few hundred miles. @Trey Hardy fixed his stuck lifter that way a couple of times now.