2013 Yukon Engine Knock...

[Trey Hardy]

This kinda sounds like a "hold my beer" idea where you end up on a fails video and a trip to the ER .... that said, would there be a detriment to trying this? Like what's the risk of screwing up even more stuff?

Yes and no my engine had close to 300,000 miles the first time it dropped a lifter the second time I was around 360,000 miles so really it was either going to clear up or blow up!one of the two… both times with the marvel mystery oil it cleared it up and got the lifter unstuck so I just started adding it each oil change after that and never had any more issues… but yea back in the day my friend had a 4.8 truck that had a bad lifter and he put a brick on the gas pedal and walked away from it until it either blew or ran out of gas… it diddnt blow it actually ran out of gas and when he started it back up it had cleared up the lifter tap… he still pulled it out and gave it to my buddy Cameron and he put it in his Camaro and ran it for another 3 years before he swapped a 6.2 in the car

 

[Trey Hardy]

Don't you have to change out a lot more stuff to do that? Like the camshaft and such?

You’ll have to change the cam shaft the valley cover and the lifters get a custom computer tune for disabling the afm but you can get the parts for around 1000-1500$ depending on if you go stock ls6 cam and lifter route vs a custom aftermarket cam setup.

 

[Trey Hardy]

This kinda sounds like a "hold my beer" idea where you end up on a fails video and a trip to the ER .... that said, would there be a detriment to trying this? Like what's the risk of screwing up even more stuff?

If it don’t clear up it could possibly tear up one of the lobes on the cam shaft not sure what else but I diddnt have the money to mess with mine at the time so I said “hold my beer” and put it in first gear and pegged it out going up the road when I got to the dock she was purring like a kitten

 

[B-train]

Refer to my previous post (#4) about the MMO or equivalent. You can do this safely and don't need anyone to hold your beer.

I've done this a handful of times with good luck

 

[jmo2610]

Refer to my previous post (#4) about the MMO or equivalent. You can do this safely and don't need anyone to hold your beer.

I've done this a handful of times with good luck

Well then it looks like that's gonna be the first thing I try then. Also I feel like I should be more familiar with the Tennessee Tune-Up. I live in Memphis!

 

[Trey Hardy]

Well then it looks like that's gonna be the first thing I try then. Also I feel like I should be more familiar with the Tennessee Tune-Up. I live in Memphis!

Just remember the mmo thins the oil so step up the grade of oil you use and use mmo as the 6th quart I used to use 10w30 I use 10w40 now

 

[j91z28d1]

will be interesting to see if it unsticks. feels like it's worth a try

from what I understand build up crude is what happens most of the time.. when you go into 4cyl mod, internally it sends oil pressure to a extra port in these special lifters, that oil pressure releases 2 pins and the lifter collapses, the push rod doesn't open the valve on those cyl. when it goes back to v8 mode, the oil pressure is vented and the next time the lifter is on the closed side of the cam, a spring pops the internal part of the lifter up and the pins lock it into full size again.

over time the internal parts can get built up gunk, or a varnish like substance. the internal part sticks down and you get the tap tap tap that slowly kills everything from banging around and spreading metal thru the rest of the engine. usually hurting main and rod bearings too.


if you can clean up that enough for it to release, it may but really even be cleaning it, just getting hot enough to expand and the banging releases it. you could be good for a while, best to make sure it never goes into 4cyl mode again thou.


other ways they stick is lack of correct lube, either to long between oil changes, crap oil, low oil pressure to the lifters, could be from bypassing somewhere else, clogged vlom screen under the oil pressure sensor, basically anything that happens that keeps it from getting lubed, doesn't have to be low pressure that would show up on your dash gauge. the internal parts of the lifter can get galled up, and get stuck so you'd have to hammer than apart.


if it is a lifter, and not a broken valve spring, something I feel would be a good idea to check before you're Tennessee tune-up, broken valve springs do happen and tap tap till they drop the valve into the piston and lunch the whole motor.

but if that doesn't work there's a guy that sells a tool, basically just a metal rod with a ground at a weird angle. you pull the intake, stick it down thru a oil passageway to the stuck lifter. smack it with a hammer, the hope is to shock the lifter enough to manually release. in one of his videos one is so stuck he hits with short air hammer blasts, but it does release. once released you have to have the ecm tuned to never. engage afm 4 cyl mode again or it will stick again at the first afm activation. there's also a feeling that this is a temp fix or just a horrible hack job. since you still have all the damaged parts still in there. afm lifters even when turned off in the ecm when new still seem to fail before normal lifters most of the time. that said these days parts quality is very lacking everywhere. you could possibly do a full delete with all the most expensive parts and it still fails.


it all depends on your level of skills. if need be I could probably pull the heads and swap the cam in a ls in a day. I just have zero desire to do that, feels like 200 more important projects I can't find time to do. it would be my very last resort. I would pull the valve cover, inspect the spring, stick a bore scope in the spark plug hole to see if a seat dropped, then once confirmed I'd get the tool and beat the lifter with a hammer haha. at least I'd enjoy that even if it didn't work. but I fully understand that is you're not comfortable pulling the intake and stuff, or don't have a place to work on it. one guy on here had to do the hammer release trick in a parking garage of his apartment, in winter up north. sounded rough, but he got it.
the Tennessee tune up is definitely a thing to try before spending 3k-7k at a shop. if I had to put $7k into my truck, I think I'd roll it into the street put a free take sign on it and happily never see it again, spend that 7k on just about anything else, even a older Gen suburban or XL and never look back haha


on a side note, when I first got my truck, I knew about the afm nonsense, so I brought hp tuners with me(I already had it from tuning my other cars) to turn it off in the ecm before I even got on the interstate heading home. 1k mile trip, once home I pulled the intake off, pulled the vlom off, installed the oil pressure block off in the afm supply passageway, clipped the gasket on the other side of the ports where the oil pressure goes to release the lifter. that way there's no chance at all any oil pressure building up in the release circuit of the afm lifters.

I feel like it's the best mod you can do to try and avoid afm issues short of a full delete. which I may still have to do at some point. but spending a few hours and 20$ to give it the best chance of survival seemed like a good idea at the time.

now turning it off in the ecm, hpt tuners is kinda expensive for a one time use and not needed unless you wanna diy tune. you can send off the ecm to get it disabled for under 100$ if you have a few days down time. or most recommend getting a black bear tune, they will tune the engine and tranny, also will disable afm for you. the afm disable at that point for them is just a drop down box and save.


good luck with it.

 

[gooffeyguy]

Good info there.

I was going to suggest pulling the valve cover and having a look-see first before doing anything.

 

[Charlie207]

Refer to my previous post (#4) about the MMO or equivalent. You can do this safely and don't need anyone to hold your beer.

I've done this a handful of times with good luck

The manual for my previous BMW V8 specifically advises to hold the engine at 3000rpms for a several minutes in Neutral to free up stuck/collapsed lifters. It worked great after letting the car sit for the winter.

 

[jdwood1111]

I just listened to yours back to back against mine and it sounds pretty similar but mine does not make that sound driving at all. Mine is not as loud from above but almost as loud in the wheel well. I’m not sure what to do yet on mine either. I posted a new video in my thread.

 

[mikeyss]

My old L9H 6.2 dropped a valve seat out of the head, and it sounded kind of like your engine does - especially when you did the driving portion of your video. Maybe get/rent a borescope, pull the spark plugs, and take a peek at the valves to make sure the valve seats still secure in the head.

 

[jmo2610]

Update so far:
The Tennessee Tune-Up was not exactly successful. Drained the old oil. Put in 5 new quarts, plus a quart of MMO. My truck wouldn't allow me to to get the RPM above 3500 in Neutral, but I let it idle normally for about 10 minutes, then revved it to 3000 RPM for about 5 minutes. Drove it around 20 miles as hard as I could in the city and interstate.
There's always the "ticking/light knocking" sound, and then intermittently, especially if I'm just holding the same speed on the interstate, there's a loud knocking. But as soon as I accelerate, even slightly, the knocking goes away. Youtube video of this below.

When I accelerated ******* the way home, it FINALLY threw a code for the CEL. Misfire on cylinder 6 (the same one I replaced the coil and spark plug on). But now also a P219B, which is a fuel trim cylinder balance code. I did notice that when trying to accelerate while around 20-30mph, it would not respond at all, and then almost "buck" into action.

 

[Blackcar]

I would stop running engine and start looking for problem if you get metal into rotating assembly going to get into big money.

 

[solli5pack]

I would stop running it as well before you damage the cam. I would say it almost certainly a collapsed lifter. On my Suburban I did the AFM delete but on my Yukon when a non AFM lifter went bad I pulled the head only on that side replaced the lifter trays and due to lack of funds used the old lifters from the Suburban. Trucks been running great for a year now. Long story short just repairing the failed lifter is not a bad option but if you plan on keeping the truck for awhile and have the funds the AFM delete is the best route. All this stuff can be done in your driveway with good tools, YouTube and help from this fourm!

 

[Geotrash]

Update so far:
The Tennessee Tune-Up was not exactly successful. Drained the old oil. Put in 5 new quarts, plus a quart of MMO. My truck wouldn't allow me to to get the RPM above 3500 in Neutral, but I let it idle normally for about 10 minutes, then revved it to 3000 RPM for about 5 minutes. Drove it around 20 miles as hard as I could in the city and interstate.
There's always the "ticking/light knocking" sound, and then intermittently, especially if I'm just holding the same speed on the interstate, there's a loud knocking. But as soon as I accelerate, even slightly, the knocking goes away. Youtube video of this below.

When I accelerated ******* the way home, it FINALLY threw a code for the CEL. Misfire on cylinder 6 (the same one I replaced the coil and spark plug on). But now also a P219B, which is a fuel trim cylinder balance code. I did notice that when trying to accelerate while around 20-30mph, it would not respond at all, and then almost "buck" into action.

Hmmmm...wonder if it coincides with v4 mode activation. Either way, I agree with the others here. Time to tear into it and fix it right. New non-AFM cam, lifters. Doable in a weekend if you have the tools.

 

[Fernando Escobar]

Hey man,
I would advise to not drive that truck in that conditionthat. I just rebuilt the entire engine on mine for the same reason, my noise was noticible when we traveled to Mexico and finally gave out upon our return to Southern California. So all my bearings, including the camshaft bearings had to be replaced so I now have a brand new motor that I rebuilt.
Good luck there’s always a lot of people here they’re willing to help

 

[jmo2610]

Hey man,
I would advise to not drive that truck in that conditionthat. I just rebuilt the entire engine on mine for the same reason, my noise was noticible when we traveled to Mexico and finally gave out upon our return to Southern California. So all my bearings, including the camshaft bearings had to be replaced so I now have a brand new motor that I rebuilt.
Good luck there’s always a lot of people here they’re willing to help

Yeah it's been sitting in my driveway untouched for several days now. Won't be able to start cracking it open until this weekend. Pretty terrified of finding the same thing you did.

 

[jmo2610]

Okay, between lots of work and some travel, I got a little delayed, but finally got the head off today. Definitely a stuck lifter. Figured that out when I took the valve cover off. Questions:
1. How difficult should it be to turn the cam over with a 24mm socket and ratchet? It seemed easy when I first started turning it, but now it's at cylinder 2 fully up and it doesn't feel like it wants to budge.
2. Do I need to have both heads off to manually turn this, or am I okay with just the one passenger side off?
3. Assuming the cam is fine, do I NEED to do both sides? Can I just replace the bad lifter and the appropriate gaskets and bolts, get it tuned to never activate AFM ever again, and go about my way?

 

[j91z28d1]

I can't say I've ever tried to turn a engine over by the cam bolt. are the rockers are the plugs still in the side with the head on it? that would make it very hard.


I'd pull the lifter out, inspect the roller, if it's perfect, then maybe the cam is OK. you'll need to inspected that lobe very well, which is kinda hard just looking down thru the hole. might be easier to pull the cam and inspect.



as for how thorough to be, that's kinda you're call. if you replace everything with oem parts, you've got decent chance of only doing it once. I say decent because oem stuff isn't the same quality it used to be, and fakes are almost impossible to spot. delete kit from a name brand place if you plan to keep it forever and have your family in it over the road trips is probably safest.


if your money is tight, wanna roll the dice and don't mind doing it again at some point. check it all very well, if you see no damage. open the stuck lifter, clean the it and see why it stuck. either varnash or galling inside. either way, release it. make sure it never activates again even once, so no plug in obd thing, turn it off in the tune directly. slame it back together sloppy mechanics style, reuse bolts and all. hell he reuses head gaskets lol, but at least do a new gasket, they are pretty cheap.


see what happens. it might run 300k. it might make it around the block.

 

[jmo2610]

Yeah the rockers are still in on the driver side. I only took off the passenger side. I was trying to turn it so that I could inspect the cam through the hole. But it seems to be... stuck? I don't want to muscle it too hard if it's supposed to be stuck there.

I'm partly trying to save money. Partly trying to save on a boatload of work. I wouldn't reuse anything that's broken. And would plan on buying OEM parts from the dealer, so I'd hope I wouldn't get fakes there.