Once I got everything apart per the fantastic videos, I found that Cylinder 7, which was giving the crazy dashboard errors in the AFM video and running rough since #7 had continuous misfires has an intake vale that never fully closes. I tried to capture in pics that it is always slightly compressed. Much lower than cylinder 1 which is also and afm cylinder.
I pulled the spark plug, shined a light and then used my phone to cover and look down the intake chamber and sure enough I could see crescent-shaped light appear as I moved my flashlight around (with no rocker arm attached per the pics)
Is this also a common problem?
Suggestions on what to do next? (By the way, I live in Austin Area if there are any shops you'd recommend)
I'm assuming I need to pull the head and have the valve replaced along with valve guide, etc. Or am I mis-diagnosing something?
Thank you for all your assistance so far.
By the way, I did by the kit, could bounce the rod a bit, but I suspect it meant nothing since my rod seems to rise as high as the other rods.
Just to close this out.. (I missed taht April 18 post BTW)... When I removed the VLOM plate, 5 bolts came out with my fingers, so yeah, they have a problem and everyone likely has a ticking time bomb.... I ordered a remanufactured Head. Carefully assembled/torqued everything down. Verified good oil lubrication coming up through the rods and have been running the vehicle for about a month.
All emissions checks are cleared and no leaks anywhere.
Changed oil and everything is clean, no fragments on drain plug magnet.
4/8 cylinder AFM working as original.
Re-inserted ODB 4 cylinder disabler.
Other things /learnings that may be of interest to pass on.
-As soon as I started it up I had coolant leading from rear of engine.. Removed intake manifold again (fun). to find the rear plug on the head was drilled out (apparently the norm for cylinder head rebuilds). A common and simple plug was ordered from amazon and got it plugged and re-installed everything.
-Emissions will not clear if the 4 cylinder disabler is plugged into ODB port
-I first left the little oil block cylinder I ordered here in under the oil pressure gauge to physically block any oil pressurization to prevent 4 cylinder mode and use odb disabler.. After I found you must remove the disabler, I tried to drive it enough to clear emission in trailer mode as it reduces frequency of 4 cylinder deactivation greatly. But on the freeway it showed on screen 4 cylinder mode switch.. Scanner then showed pending codes for 4 cylinder activation. Thanks to the tip of removing that rear plastic noise baffle, I was able to remove oil pressure sensor easily (with proper socket) and use needle nose pliers and pull them open (vs squeeze) to grab the inside wall of the cylinder insert and pull it out. Dropped in a filter to make it stock. That let me get emissions to clear. (vs leaving it in and getting ECU reprogrammed).
The 6.2L is actually known for this issue. I've seen it before on an LS3 which is basically the same thing. For some reason they didn't do a very good job with getting the seat pressed in their tight enough. The last one I seen this on completely blew the piston to pieces and destroyed the head You got lucky. If you want you can just put a new piston in there. I probably wouldn't run that piston it looks like it hit it pretty hard. You might actually be able to even repair that cylinder head yet by installing a new oversized seat.
HI, so pulling head tomorrow to take to a local reccomended shop for the valve job. GM is sold out of the adjustable lifters and I could swear I saw some used/inspected ones here for sale but now can't locate them. I want to replace the #7 lifters. Do you have any left? i've seen lots of horror stories of junk chinese ones not pumping oil and located this one as a most likely potential to use... Thoughts?.... https://www.amazon.com/gp/product/B0BYXX82ZV
This is not a common Issue at all. However it is possible of course. Did this have a floppy loose rocker like in my video? If so, it's possible the lifter collapsed and the pushrod hit the rocker just right (or wrong depending how you see it) that it opened the valve too far causing interference and bending it. Regardless this means the head has to come off and should get a new valve, full valve job and get it resurfaced. I would recommend doing both heads but you could get by with one. Only thing is, if you go that far maybe do a full delete at that point? You should at least replace the lifter in question now though.
Oh, Forgot to mention the vehicle.. 2010 L94 6.2L Cadillac Escalade ESV (suburban)