2012 Yukon XL Denali 6.2L Cam Swap Thread

[Geotrash]

I hate to even say this, but it sounds like you have a roller locked up on a lifter and scrubbing the cam. That’s the same sound my 2007 made when the #5 intake lifter locked its roller. I hope I am completely wrong, but I had flash backs when I played your video.

That's really good validation of what I'm thinking, thanks Wade. It sucks to think about tearing down an engine I just built to last because one of the new parts I put in it is failing in the first 3 hours of running. At least this time I'll be able to do the job in half the time because I'll already know how to do it and have all of the tools. My worry is that if it's wiping the cam, I'll have metal in there doing damage already. I'll have to inspect the surfaces on the cam bearings. I'll likely do the oil pump this time as well. What's puzzling me is why the lifter is failing. I had one already that was bad before I put it in, but the others went in without issue. Apparently it's also devilishly hard to get lifters right now because of supply chain disruptions. And apparently all of the manufacturers use pintle valves made by the same company in Germany.

One thing floating around in my head is the possibility that one of the lifters may be slightly oversized and hanging up in its bore. The problem with the lifter that was bad from the get go is that it was oversized by .006 and wouldn't fit. I should have mic'd all of the others because a slightly oversized lifter would explain why, as the engine warmed up during that long run a couple of nights ago, it quieted down. Aluminum expands faster than steel so the bore may have opened up just enough.

 

[Geotrash]

I found the email from 2016 to BTR

"
Hi Jared, I was able to take off all 16 valve springs yesterday, here are my findings.

-14 of 16 seals were completely off. 2 were still on, but were loose and about to come off.
-One seal was shedding metal (the oil near this seal was silvery)
-The seats were the correct size

I put on Fel-Pro SS70945 seals, drove the car about 100 miles and did numerous WOT pulls and all of them are still where I put them down on the guide. I noticed the fel pro seals were stupidly easy to put on, they could almost be slid on by hand. While the BTR and Lunati seals took tons of effort to put on even fully oiled up. I followed the outlined "press" method to a T and all of them still came off, so it looks like there is an issue with these seals since the fel pros are still fully down on the guide.

Pretty much all of the seals are fully intact, I can send them in for inspection if you think that would help."

This is HUGELY helpful - thank you Mike. I was finally able to find the right Fel-Pros with this part number and they're on the way, just in case. I'm going to run a few more checks but will likely start the teardown on Saturday.

Thanks to all for the great support - sure helps to not feel alone in this process. Gadzooks I wish GM had designed these with the lifters to be removable without having to take off the heads.

 

[1BADI5]

Did you soak the new lifters in oil for 24-48hrs before install?

For the belt noise......that dressing shit makes is worse everytime. With the truck running spray the belt down with brake clean, that will get all of the contaminates off from the belt, IE coolant, oil

 

[thompsoj22]

This is HUGELY helpful - thank you Mike. I was finally able to find the right Fel-Pros with this part number and they're on the way, just in case. I'm going to run a few more checks but will likely start the teardown on Saturday.

Thanks to all for the great support - sure helps to not feel alone in this process. Gadzooks I wish GM had designed these with the lifters to be removable without having to take off the heads.

Just been watching your build, Not trying to tell my story just give you a basis for a good attitude! I turn wrenches for a living on helicopters, There are tasks/repairs that i dread, They normally re'occur based upon negligence of the pilot/aircrew but with no blame whatsoever, Just my boss telling me to go back out and fix it! My mental attitude at the begining of the task is dread, "FK this" and every other explative i can recite but as i move forward i perform the task faster and without error, kinda get caught up in what im doing and the anger go's away, So gather your wits, put on your favorite tunes and patiently retrace your steps! Faster than the first time, You are going to find out whats wrong and we are all waiting to hear what it is! Hang in there!!!

 

[Geotrash]

Did you soak the new lifters in oil for 24-48hrs before install?

For the belt noise......that dressing shit makes is worse everytime. With the truck running spray the belt down with brake clean, that will get all of the contaminates off from the belt, IE coolant, oil

Yes, I sure did soak them for about 16 hours anyway. Although I've read conflicting guidance on that. On the Vinci website they have a series of technical blogs and one of them specifically says not to "soak" the lifters in oil but instead make sure they're slathered well in oil before installing them into the bores. I also used the Permatex assembly lube because I didn't want a thicker grease-like lube to interfere with the small passages in the lifters.

I agree with you on the belt dressing, so all I was looking for was a change in the tone of the chirp but it literally had zero effect. I'll try the brake cleaner idea just in case. Nothing to lose.

 

[Geotrash]

Just been watching your build, Not trying to tell my story just give you a basis for a good attitude! I turn wrenches for a living on helicopters, There are tasks/repairs that i dread, They normally occur based upon negligence of the pilot/aircrew but with no blame whatsoever, Just my boss telling me to go back out and fix it! My mental attitude at the begining of the task is dread, "FK this" and every other explative i can recite but as i move forward i perform the task faster and without error, kinda get caught up in what im doing and the anger go's away, So gather your wits, put on your favorite tunes and patiently retrace your steps! Faster than the first time, You are going to find out whats wrong and we are all waiting to hear what it is! Hang in there!!!

Thank you, John! That's exactly the same for me. And once I get in the zone, it's pure bliss. Psychologists call it "Flow".

Love helicopters! I fly fixed wing (I've owned a Cessna 182 for 20 years) but I have lots of passenger time in Alaska in A-Stars, Twin Stars and Hughes 500s from back in the day when I was a field geologist. I used to help the mechanics with some of the bigger jobs when they needed extra hands. I helped remove/install/track the blades on an A-Star after we cracked the 3-pointed carbon fiber hub at the center of the rotor assembly doing heavy longline work. Cool stuff and a good mechanic is worth their weight in gold when you're out in the middle of nowhere.

 

[1BADI5]

Ok, I was just curious.

I soaked mine for about 36 hours. I used Royal Purple Max Tuff assembly lube on the push rods, rockers, oil pump, timing chain and cam

 

[ls1frc]

The rep who I spoke to at Johnson said to never soak lifters. Just oil the outside and run em.

 

[thompsoj22]

Thank you, John! That's exactly the same for me. And once I get in the zone, it's pure bliss. Psychologists call it "Flow".

Love helicopters! I fly fixed wing (I've owned a Cessna 182 for 20 years) but I have lots of passenger time in Alaska in A-Stars, Twin Stars and Hughes 500s from back in the day when I was a field geologist. I used to help the mechanics with some of the bigger jobs when they needed extra hands. I helped remove/install/track the blades on an A-Star after we cracked the 3-pointed carbon fiber hub at the center of the rotor assembly doing heavy longline work. Cool stuff and a good mechanic is worth their weight in gold when you're out in the middle of nowhere.

Currently maintaine the MH60-S for a SAR unit, I hold the A&P cert but have allways contracted for the military as it pays way better. Im anticipating what you will find on teardown, anything that you replace this time consider OEM components? Hey, Thanks for the new word "flow", Monday morning passdown ill try to go straight to the "flow zone" with my workload!

 

[iamdub]

Curious as to where the magic number of .0025” came from?

... The .0025 number came from another member here who suggested it to get the quash a little tighter for better combustion.

I just found this thread and had to catch up from the beginning. I realized later in the thread that this particular point is irrelevant now, but wanted to clarify for anyone else that may be reading.

@Snowbound: The "magic number of .0025" " is actually supposed to be .025" (twenty-five thousandths). It's a safe amount to shave for "free" across-the-board power. Since the machinist already has the heads set up for a cleaning pass, it doesn't take any more effort to shave them so there shouldn't be any additional cost, or very minimal at most. In an engine that should be running 91/93 in stock form, will be getting a cam that MIGHT cost a slight bit of low-end power and will be getting non-stock push rods due to the cam, it's one of those small no-brainer mods. Also, to clarify, the shave is to bump compression. The thinner head gaskets we also discussed is what was for tighter quench/better combustion.