2012 Yukon XL Denali 6.2L Cam Swap Thread

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Dave
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Got the cam in and the heads, exhaust manifold, intake manifold and accessories all mounted up today. Only things left to do are the radiator and fans, and the main serpentine belt. Hope to have it wrapped up tomorrow. I could’ve gotten it done in one day but farted around during the day with a few other projects and our puppy.

I feel so much better with those GM lifter trays in there. Night and day difference when I installed the lifters this morning. They held them FIRMLY in place. Can’t believe those cheap trays I got from Vinci caused me so many headaches.

I didn’t drop the oil pan so the oil pump was in the way and I couldn’t see the dot on the crankshaft to line it up. This caused me some distress until I remembered that #1 piston TDC is pretty easy to spot with the heads off. Lol. Good to go!

By the way, I’m convinced that the Morel lifters I put in before are superb. They endured a ton of abuse courtesy of those $&)@!! lifter trays and kept going, only letting me know there was a problem when the damage to one of them has become severe. After a careful inspection of the rest of them with a hand lens, only 3 of them seem to have sustained damage, while many of the cam lobes had scuffs from the lifters twisting in the trays.
 
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Ahhhh… smooth, quiet idle.


Unfortunately though, I accidentally stripped the hole for one of the bolts that holds the oil cooler lines onto the pan so I had a nice stream of an oil leak and couldn’t take it for a test drive. I picked up a helicoil kit (threads are M6-1 if anyone is wondering) and will hopefully have time tonight to get that installed. It’s a difficult working angle so I have a flexible shaft for my drill and a 1/4” shank bit that should do the trick.
 
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Got the helicoil in and it held great. Leak is fixed 100%. Put the wheels on and took it for a longish drive. It runs perfectly apart from the computer doing some adjustment after having the battery unplugged for so long. As I drove the shifts and the throttle response got smoother. Valvetrain is quiet like buttah. Plenty of power from this cam and the idle is smooth. It’s a sleeper. Gonna use it to pull the camper this weekend.

I’ll make a final parts and lessons learned post when I get a moment in the next few days to close out the thread. Thanks for riding along.
 
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As promised, here is the updated final parts list, for the third time :), plus as many notes from the job as I could remember to share.


Special tools to have on hand before you start:

Notes on the job:
  • Before you do anything, and I mean anything, throw those cheap lifter trays that you picked up on Amazon or even from a reputable supplier, in the trash. Then buy yourself some OEM GM lifter trays from Summit or Rock Auto. OEM trays hold the lifters like a grudge. Failing to use OEM trays will cause you to have to do this job again and again. Trust me on this, speaking of grudges.
  • Soak those exhaust manifold bolts with penetrating oil. Then sit back with a beer while it goes to work because you have some extra time. Well, actually you don't because the whole job is a lot easier if you remove the front wheels and the fender liners. Remove the plastic splash pan below the engine too. Might as well get to work.
  • I set the front of the truck on jack stands placed under the frame on both sides just high enough to remove the front wheels and be able to slide underneath when needed. Lifting it any higher makes working on the top side a PITA and any lower makes it harder to work the wrenches for removing the cross member, oil pan, etc.
  • Cut a pool noodle and duct tape it around that 6" knife blade that comes out from the hood latch so you don't commit Hari-kari when you accidentally drop the water pump and go to catch it.
  • You don't have to remove the differential on 4WD/AWD models to get the oil pan off. All you have to do is remove the axle shaft bolts on the passenger side and separate the CV axle from the flange. Then remove the 2 differential mounting bolts on the same side. The differential will hang plenty low enough to wiggle the oil pan out without having to drop the diff completely. Confucius say: "If you want to know the easiest way to do something, watch a lazy man."
  • Put in a new oil pump and use the right pickup tube o-ring when you install it. It will be the thicker of the two on a truck engine. I didn’t do this the first time I did the job and regretted it when I didn’t have great oil pressure afterwards. So I did replace the pump the second time and used a Melling high volume pump. That was a good decision.
  • Rather than set up a whole contraption to prime the new oil pump, I soaked the pump in oil for a few hours before I installed it and then removed the plate covering the rotor on the pump and smeared some grease around in there. I didn’t completely pack the pump with grease but put in a couple of fingers’ worth. It paid off with immediate oil pressure on the first startup.

Getting the cam and lifters out (tips and notes only):
  • Take off the intake manifold.
    • I started by removing all of the belts and pulleys on the front of the engine, removing the radiator hoses, etc. I also removed the radiator fans and cooler lines so I could get the radiator out. You could wait and do this part later, but it all has to go before you can pull the cam out, so you might as well do it sooner than later. Getting the cooler lines off the radiator is easier than it looks - just have to use a pick to get the spring clips off. Wear safety glasses, then go to Amazon to order some new ones because you ain't never gonna see the ones you took off again.
    • Make sure you relieve the fuel pressure on the fuel rail on the manifold or you'll never get the fuel line separated. Use the right size fuel line disconnect tool - usually the gold one. You can get a set for like $15 at AutoZone. Place a rag under the Schrader valve before you release the pressure to catch the fuel that comes out. It's probably best not to have a cigarette or a joint in your mouth at this point.
    • You don't have to remove the connectors for each coil pack - just the main connector for the rack holding the 4 coils on each side. You do have to remove the connector for each injector though, which is easy. Just slide up the little white clip on each one and squeeze in the tab below it, gently rocking it loose.
    • I like to label each connector with a silver or black sharpie but you don't have to. The way the harness is made with different wire lengths and connectors, it's pretty easy to get everything back in the right places without labels. Once I get all of the connectors off, I like to suspend the harness in 2 places with zip ties to either someplace on the cowl or one of the windshield wiper arms to keep it out of the way.
    • Use a diagram to get the right sequence for loosening the intake manifold bolts. I had no problem getting to all of them, even with my big paws. I found that a 10mm deep well socket and a short extension made it easier, and a cordless ratchet will make you think you died and went to heaven. The bolts were designed by an engineer with a whole lotta angst because they have a sleeve with a washer welded to it about a half inch from the bottom of each one that makes it almost impossible to remove the bolts because when that damed washer catches the head is dead-even with the fuel rail so you can't get any leverage on 'em. But after some whisky to clear my thinking I found that rocking them a little bit while pulling up allowed me to remove them completely. You can still get the manifold off without removing the bolts entirely, but if your luck is like mine, you'll end up with a deep scar across one or more of the intake ports from where the bolts dragged.
    • The intake gaskets are clipped to the manifold on each side, which makes removal and installation easier. That was designed by an engineer full of kindness, with empathy for the poor bastard that has to install the thing.
  • Cylinder heads (tips and notes only).
    • Before you put a socket on those exhaust manifold bolts, soak them with penetrating oil again. You don't need to remove the heat shield bolts, just the bolts that mount the manifolds to the heads. They're much easier to get to from inside the wheel wells with the liners removed and with a long extension. Be patient and slow when loosening them, and do not use a motorized wrench of any kind on them. I soaked mine in penetrating oil multiple times over 2 days and had no trouble getting them out, thankfully. Also, I did not need to separate the manifolds from the exhaust flanges below them. I was able to use the plastic handle of a harbor freight dead blow hammer to create enough clearance to get a socket on each of the cylinder head bolts without boogering up the ports.
    • Remove the cylinder head bolts 1/4 turn at a time using the sequence in the service manual, which is the reverse of installation. Use ARP cylinder head bolts. They're easier to install because you can torque them without needing to fuss with an angle gauge like you do for the OEM torque-to-yield bolts. I know, right? And, they're reusable in case you have to do the job three times, like I did.
    • Use new *OEM* lifter trays for non-AFM engines. I can't stress this enough. Cheaper trays will allow the lifters to wiggle/rotate slightly and will eventually lead to lifter and cam failure.
    • You don't need abrasives to clean the cylinder head and block mating surfaces. Use the Permatex chemical gasket remover and clean, lint-free rags. https://www.amazon.com/Permatex-806...permatex+gasket+remover&qid=1612204042&sr=8-1
    • I didn't bother to have my heads machined or the valves lapped since everything was in such good shape. However I did install new valve stem seals, matched BTR springs and a BTR trunnion upgrade kit.
    • Don't forget to blow compressed air into the cylinder head bolt holes before installing the heads. You don't want any liquid or debris in there when you torque the bolts down. And when you think they're clean, shoot another puff of air in each one just to be sure. Then hit 'em with a clean, dry Q-tip from your wife's makeup basket in the closet beside the bathroom sink, soaked in carb cleaner. Do this before she wakes up so she won't interfere with the heist.
  • Cam and lifters.
    • I used a magnetic pickup tool to pull each of the lifters out. Pure genius even though I stole the idea from some other guy on a forum. The main thing is I remembered the trick at the precise moment I needed it.
    • You can use 5/16" wooden dowel rods cut to 24" long from the hardware store to keep the lifters from falling in when you remove the camshaft. You don't need to do this if you have the lifters out, of course, but if for some reason you need to pull the cam for inspection after the heads are back on, as I did, this trick can come in handy. Once you insert the dowels you just spin the camshaft back and forth a few times using two water pump bolts threaded into the holes in the end of the cam to seat the lifters into the trays so they'll stay. All of this assumes that the trays in there aren't cheap knock-offs from some guy in Florida and can actually hold a lifter in place.
    • I used a 3-bolt cam and removed the VVT hardware accordingly and installed a new correct timing cover. I had to do some finagling to the cam position sensor wiring to get it to sit okay behind the harmonic balancer but it worked out fine. Lots of folks will tell you to keep VVT. Those people aren't as lazy as me and don't mind taking the starter off to put a thingy on the flywheel to keep it from turning while they torque the piss out of the single cam bolt.
    • I used the comp cams assembly lube on the new cam before I installed it and it has fabulous film strength to protect the cam and lifter rollers at initial startup. It's like one of those boogers you get after a bloody nose that you can stretch out 6 inches before it flips around your finger. I did not use the assembly lube on the lifters themselves as I’d soaked them in clean motor oil overnight.
    • It’s possible to get the timing chain on the cam sprocket with the oil pump and crankshaft sprocket in place, and then get the camshaft gear onto the cam. If it feels too tight when you try, it means that you have a link of slack somewhere on the crankshaft sprocket. I used a clean shop rag stuffed in the gap between the oil pump and the pan to hold the chain up against the bottom of the crankshaft sprocket to keep the chain seated properly, giving me enough slack to get it over the camshaft sprocket and onto the cam. If your timing mark is off a tooth or two, you can hold the cam sprocket in your hand with the chain still around it and shift the chain with your index finger one link and tooth at a time until it’s right.
  • Other notes
    • The dipstick tube was easier than I thought it would be to seat. I set it in place through the exhaust manifold tubes and had an assistant pull it up slightly and feed it back down slowly while I laid under the truck and guided it with my fingers. I couldn’t see where it goes but could feel it with my fingers. Reminded me of a drunken night in college when my libido overruled my inhibition. And I just threw up in my mouth a little bit.
    • Don’t forget to use a small dollop of black RTV on the oil pan gasket at the rear corners by the flywheel. You'll know where I mean when you see the oil pan gasket. You'll also need a dollop on each front corner right before you install the timing cover.
    • I used a floor jack under the exhaust Y pipe to help me get the exhaust manifolds into position for assembly. Be careful with the exhaust manifold bolts - they're super easy to cross-thread. They should go in very easily if they're started right. Start with the ones in front and work your way back, lowering the jack slightly each time to line up the next hole perfectly.
 
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One final note to close this thread out. We hauled the camper to West Virginia yesterday, and drove over a section of I-64 with 7% grades that we have driven over with the camper several times before. This is a better towing cam than the BTR stage 2 truck cam. My guess is it’s because it is designed specifically for the 6.2. Takes advantage of the better flowing heads. I was able to climb the same hills as last time in a higher gear for much longer. It’s so powerful on the low end, I had to remember to keep my foot out of it several times. It’s a total recalibration of my driving senses while towing.
 
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