2012 Yukon XL Denali 6.2L Cam Swap Thread
- Thread starter Geotrash
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Ah, it's still out there as a specter - it's why I "upgraded" but now am thinking maybe I should've stayed stock. Any more color as to why they failed in your case?
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Thanks for the thought. If I have any issues with oil pressure after this knocking is resolved, I'll make sure those are sealed with a thin layer of sealant. Side note: I did replace the camshaft thrust plate with new OEM, as I understand that can be a source of pressure loss also.
The trunions are just junk, poor design. Stay stock or bronze bushing. Comp was the worst offender, BTR are a bit better metal so will last longer but eventually will wear out like below. The bronze are OK, but since they're soft, they are wearing constantly and will need replacement every 10-20k. With mild builds, there is no reason to not stay stock. If going above .600 lift, then you can think about beefing up the rocker arms or going aftermarket.
Ive used btr, straub, and che. CHE was my favorite, they just drop in and are floating, no press needed. But again, it's now another wear item you have to maintain. Stock rockers require no maintenance.
https://www.corvetteforum.com/forums/c6-tech-performance/3546465-fail-comp-cams-trunion-upgrade.html
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Update: Since I don’t have an adjustable pushrod, I used the turns of the bolt method to measure the preload on both the intake and exhaust valves for the number one cylinder. I came up with about .087 for both. It was also possible to depress the lifters with the pushrods a bit with firm finger pressure. This doesn’t bother me though but would explain startup noise until they pressurize. What’s still haunting me is that loud rapping noise that sounded like it was coming from the #1 or #3 cylinder area when it was running. Sounded like bad news to me.
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Thanks again, Mike. I'll order some stock rockers to try. When I start the engine again after the diagnostic work, I'll capture a video and share here.
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Spent a half hour on the phone with Roger tonight and he's great. I'm going to pull the rockers off the #1 & #3 cylinders and get a look at the lifter positions from above. He's also concerned that the lower oil pressure I'm experiencing since the build could be a contributing factor. I put the same color and size (measured with a caliper) O-ring into the pickup tube as I took out, and it was a nice, snug fit, but it could still be an issue. He wants me to switch to 15w-40 conventional oil for a bit to see if that lifter will pump up with more pressure. Stay tuned, friends!
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I have good news! The thicker oil quieted everything down and it’s running quiet as a mouse. I went with Valvoline 15w-40.
There was also another problem that was confusing the issue. The A/C belt is a new stretch belt and was chirping loudly at the same frequency as the lifter taps but I couldn’t isolate it from the lifter noise until they quieted down. It was so sharp in tone that it sounded like knocking from inside the truck and standing over the engine.
My mechanics stethoscope helped me to rule out valve train and water pump noise as well. I ran it for an hour tonight and the belt is almost silent, as is the valve train. Hooray!!! Thanks for all of the advice and guidance, gents!
I’ll just have to keep an eye on that oil pressure for a while. I’ll also follow up with a lessons learned post to help anyone else who wants to embark on this job. I love the cam - makes a noticeable difference on the low end. Very little throttle needed to get good acceleration.
Also, I can’t say enough good about Roger Vinci. The man knows his stuff, and provides outstanding support. Thanks to those who recommended him - that was a key tip!
There was also another problem that was confusing the issue. The A/C belt is a new stretch belt and was chirping loudly at the same frequency as the lifter taps but I couldn’t isolate it from the lifter noise until they quieted down. It was so sharp in tone that it sounded like knocking from inside the truck and standing over the engine.
My mechanics stethoscope helped me to rule out valve train and water pump noise as well. I ran it for an hour tonight and the belt is almost silent, as is the valve train. Hooray!!! Thanks for all of the advice and guidance, gents!
I’ll just have to keep an eye on that oil pressure for a while. I’ll also follow up with a lessons learned post to help anyone else who wants to embark on this job. I love the cam - makes a noticeable difference on the low end. Very little throttle needed to get good acceleration.
Also, I can’t say enough good about Roger Vinci. The man knows his stuff, and provides outstanding support. Thanks to those who recommended him - that was a key tip!
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Great news!
BTW, I said F that stretch belt and went with a belt and tensioner off from an earlier model Tahoe. I have the part numbers posted in my build thread.
For me, I went with a new HV OEM oil pump and I'm running 7qts of 10w30.
BTW, I said F that stretch belt and went with a belt and tensioner off from an earlier model Tahoe. I have the part numbers posted in my build thread.
For me, I went with a new HV OEM oil pump and I'm running 7qts of 10w30.
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Thank you so much for providing folks here with your detailed steps, challenges, successes, and issue resolutions during this project. I am looking forward to reading your upcoming lessons learned, to complete this communication and learning process. Our collective knowledge base has been increased.
This project, along with active participation from so many folks here FULLY justifies the existence of this Forum, AND is a testament to why this Forum is so damn successful! Everybody wins!
avalonandl
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This is a very informational thread but has confirmed one thing for me: If I want more power I am going to supercharge. No breaking into the engine.
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Well, I spoke too soon. I started it this afternoon and there was a huge plume of blue smoke after sitting overnight, and that chirping noise was back with a vengeance. It had become almost silent last night. I put dressing on the belt and there was no change so it must be coming from elsewhere but I cannot figure out where. I started it a second and third time after sitting for 30 minutes each time, and there was another smaller blue cloud of smoke each time, leading me to believe that it’s something with valve stem sealing.
The only question at the top of my mind right now is could one or more of the valve stem seals have come loose? It would explain the blue smoke at startup but I don’t know if it would explain the chirping noise. I’m wondering if maybe I didn’t get them installed correctly. I noticed when I installed them that they didn’t seat all the way down against the base of the valve stem riser. Wondering if I didn’t get them all the way on correctly.
Attaching a video to give you a sense of it the noise at least. Again, the noise almost completely disappeared last night after running for an hour or so. So frustrating.
Update: I got the valve stem seals seated right, based on information I found on another forum, but it's still possible one or more of them could have lifted off the pedestals.
The only question at the top of my mind right now is could one or more of the valve stem seals have come loose? It would explain the blue smoke at startup but I don’t know if it would explain the chirping noise. I’m wondering if maybe I didn’t get them installed correctly. I noticed when I installed them that they didn’t seat all the way down against the base of the valve stem riser. Wondering if I didn’t get them all the way on correctly.
Attaching a video to give you a sense of it the noise at least. Again, the noise almost completely disappeared last night after running for an hour or so. So frustrating.
Update: I got the valve stem seals seated right, based on information I found on another forum, but it's still possible one or more of them could have lifted off the pedestals.
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Thinking about this some more and doing a bunch of desk research this afternoon, I am increasingly convinced that I have two problems:
1/ Some of the valve stem seals may have lifted off the pedestals, causing the smoke at startup. The OEM seals are integrated into the land that the spring sits on, but because I’m running dual springs now, the valve stem seals that came with the springs are separate from the spring land, and there is a gap of an eighth of an inch or so between the bottom of the seal housing and the land when they’re fully seated. I was careful to seat these the right way without damaging the tiny spring that keeps the seal tight, but there are lots of reports online of this type of seal coming loose, particularly with dual valve springs.
2/ A failing lifter. I listened to several other videos online of failing lifters with a chirp, and they sound identical to my ear to my engine.
Needless to say, I’m not a happy camper right now. I will tear it down again, but I’m not gonna be happy about it. It’s ironic that I’m experiencing precisely the problem I was hoping to avoid with this upgrade… A failing lifter.
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1/ Some of the valve stem seals may have lifted off the pedestals, causing the smoke at startup. The OEM seals are integrated into the land that the spring sits on, but because I’m running dual springs now, the valve stem seals that came with the springs are separate from the spring land, and there is a gap of an eighth of an inch or so between the bottom of the seal housing and the land when they’re fully seated. I was careful to seat these the right way without damaging the tiny spring that keeps the seal tight, but there are lots of reports online of this type of seal coming loose, particularly with dual valve springs.
2/ A failing lifter. I listened to several other videos online of failing lifters with a chirp, and they sound identical to my ear to my engine.
Needless to say, I’m not a happy camper right now. I will tear it down again, but I’m not gonna be happy about it. It’s ironic that I’m experiencing precisely the problem I was hoping to avoid with this upgrade… A failing lifter.
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I actually did have that issue with the seals coming loose before. They were with BTR dual springs IIRC. I resolved the issue by buying Felpro valve seals of the same type and never had an issue.
That noise is definitely not normal, have you run the vehicle without belts yet?
That noise is definitely not normal, have you run the vehicle without belts yet?
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I haven’t run the vehicle without the belts yet, but I did put on belt dressing today on both belts and it made no difference. That said, I suppose it could be the water pump but when I use my stethoscope to listen to it, it’s quiet. Tensioner pulley bearings are less than a year old, so I don’t suspect those, and the stethoscope shows them running quiet as well.
You don’t happen to have a part number for those Fel-Pro seals do you?
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You don’t happen to have a part number for those Fel-Pro seals do you?
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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.
Yeah, unfortunately my GTO made the same sound when the lifter was bad. But to have that happen so quickly means a defect in one of your products. As you mod LS motors, you tend to find the reliable brands and stick with them. For me, it's always Cam Motion on the cams and Johnson on the lifters.
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."
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