2013 Yukon Engine Knock...

[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.