2012 Yukon XL Denali 6.2L Cam Swap Thread

[Geotrash]

Here we go!

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[Geotrash]

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[wjburken]

 

[Geotrash]

Made some progress today. Only had a few hours to work on it but got the front fascia off, coolant drained and the intake manifold off. Hope to get the heads off this week and over to the machine shop.

As an insurance policy I also ran a logging session with the Autocal v3 and also pulled the stock tune files off the ECM before starting the work. I realized that it would enable Black Bear to prepare a tune to get it up and running while it’s out of service, and then I can work with Steve Frost for a final in-person tune.

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[Geotrash]

Had about an hour this evening to get the driver’s side cylinder head off. Seems strange to be taking apart a perfectly good engine, but also helpful to know that when it goes back together it will be better than new in many ways.

All of the parts look like new, all of the rollers on the lifters roll smooth as silk, so it’s good to know that it was well cared for. I got lucky on this side, and had no problems with the exhaust manifold bolts. Fingers crossed for the passenger’s side.

Question for you experts: I’m taking the heads into a machine shop to be milled down .0025, per recommendation from iamdub. Is there anything else you recommend that I have them do other than clean them up? I have new Viton seals for the valve stems I could have them install, and will be doing the new trunnion upgrade on my bench when I get them back, but would you recommend having them lap the valves or anything?

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[Just Fishing]

 

[Geotrash]

Both heads are off and headed to the machine shop this afternoon. Some lessons learned:

• Take both front wheels off and the wheel well liners out. You'll thank yourself.
• Chemical gasket remover foam works incredibly well. I was able to get all of the head gasket residue off the block without any abrasives. The stuff goes on with the tiny plastic bristle brush built onto the top of the can, sits for 30 minutes, and wipes off with a shop rag and very little elbow grease.
• The oil pan has to come off (dropped a few cm, anyway) to get the oil pump off. I'd hoped to be able to do it without dropping the pan, but can't get a wrench on the pickup tube bolt no matter what I try.
• The exhaust manifold bolts take time, patience and penetrating oil to remove without snapping one off. I was patient, and got very lucky.
• The manual says the exhaust manifold to flange bolts need to come out. I didn't need to do that. I used the plastic handle of a dead-blow hammer to wedge in between the manifold and the head to get the bottom row of head bolts out on both sides. Plenty of room.
• Take the head bolts out in the reverse order of installation, loosening them 1/4 turn each in sequence. Takes about 15 minutes per head to do it this way, but reduces the chances of aluminum head warpage and cracking.

Here's a shot of the new flat valley pan going on. Happy wrenching!

 

[Jason in DLH]

Nice build!

Since you’re so deep into it already....

Mind as well just go ahead with a bore and stroke. I believe you could safely get a 427 out of the block.

 

[Jason in DLH]

 

[kbuskill]

Had about an hour this evening to get the driver’s side cylinder head off. Seems strange to be taking apart a perfectly good engine, but also helpful to know that when it goes back together it will be better than new in many ways.

All of the parts look like new, all of the rollers on the lifters roll smooth as silk, so it’s good to know that it was well cared for. I got lucky on this side, and had no problems with the exhaust manifold bolts. Fingers crossed for the passenger’s side.

Question for you experts: I’m taking the heads into a machine shop to be milled down .0025, per recommendation from iamdub. Is there anything else you recommend that I have them do other than clean them up? I have new Viton seals for the valve stems I could have them install, and will be doing the new trunnion upgrade on my bench when I get them back, but would you recommend having them lap the valves or anything?

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Just saw this...

My recommendation would be to have the machine shop pull a vacuum on the valves to make sure they are all sealing properly. If they are sealing well then there is no need to lap the valves.

I always have them Magnaflux the heads to make sure they aren't cracked BUT I have always pulled heads because of blown head gaskets.

 

[wjburken]

Just saw this...

My recommendation would be to have the machine shop pull a vacuum on the valves to make sure they are all sealing properly. If they are sealing well then there is no need to lap the valves.

I always have them Magnaflux the heads to make sure they aren't cracked BUT I have always pulled heads because of blown head gaskets.

By Magnaflux, you mean dye penetrant testing, not mag particle right? I think his heads are aluminum so would need to use dye penetrant to check for cracks.

 

[kbuskill]

By Magnaflux, you mean dye penetrant testing, not mag particle right? I think his heads are aluminum so would need to use dye penetrant to check for cracks.

I guess thats what I mean... my machine shop knows what I mean... lol

Seriously though, I have never really researched the process, I have always just dropped them off and had them check for cracks. However they do it... maybe its black magic... lol

 

[wjburken]

I guess thats what I mean... my machine shop knows what I mean... lol

Seriously though, I have never really researched the process, I have always just dropped them off and had them check for cracks. However they do it... maybe its black magic... lol

Only reason I know is I used to be the Engineering Manager for Magnaflux designing their mag particle and penetrant equipment.

 

[Geotrash]

Thanks for the additional guidance, gents. Work has been busy (the usual Q4 madness), so have been only making slow progress. Procrastinating about dropping the oil pan, too. On one shoulder, there's a red angel that says "You really only need to drop it enough to get the pickup tube bolt out." And on my other shoulder is a blue angel saying in my dad's voice: "Remove the pan fully so you can do the job right, clean it out and get a new pan gasket in there." Of course, that means dropping the cross member, lowering the steering rack and the front diff. All doable, just a PITA.

 

[kbuskill]

Thanks for the additional guidance, gents. Work has been busy (the usual Q4 madness), so have been only making slow progress. Procrastinating about dropping the oil pan, too. On one shoulder, there's a red angel that says "You really only need to drop it enough to get the pickup tube bolt out." And on my other shoulder is a blue angel saying in my dad's voice: "Remove the pan fully so you can do the job right, clean it out and get a new pan gasket in there." Of course, that means dropping the cross member, lowering the steering rack and the front diff. All doable, just a PITA.

If you still have the intake off you can unbolt the engine mounts and jack the engine up enough to remove the oil pan without dropping the steering rack.

If the heads are still off you will have even more clearance on the firewall.

There are spots cast into the block that stick out on either side that you can jack from or if you have an engine hoist/cherry picker you can lift it from above.

This is how I did mine on the Burb but mine is 2wd so yours may require dropping the front diff slightly to clear.

Do it right or do it twice... lol

 

[Geotrash]

If you still have the intake off you can unbolt the engine mounts and jack the engine up enough to remove the oil pan without dropping the steering rack.

If the heads are still off you will have even more clearance on the firewall.

There are spots cast into the block that stick out on either side that you can jack from or if you have an engine hoist/cherry picker you can lift it from above.

This is how I did mine on the Burb but mine is 2wd so yours may require dropping the front diff slightly to clear.

Do it right or do it twice... lol

I like that idea because I can also do the motor mounts at the same time. Thank you.

 

[Snowbound]

Curious as to where the magic number of .0025” came from? Drop the heads off and tell them to surface them to under a 40Ra and they will make sure they are straight and clean. Most MLS head gaskets can handle a surface that is 60-70Ra microinches but some require cleaner 30-50Ra. The cleaner is always better rule applies here too. No real need to check for cracks since you didn’t have any issues. Valves shouldn’t need any work either. Even the umbrella seals should be fine but if you want to have them changed while out, I get it. Trunion upgrade is always a good thing and that’s about all I would really recommend.
Turn your intake upside down and see how much oil comes out. That will tell ya if you need to do the catch can like everyone else does.
Take your time, mark the bolts once torqued to spec, be sure everything is clean, blah, blah, blah! You got this, it’s about as straight forward as it gets. Oil pan sucks though. No way to sugar coat it. I hate doing them and I feel for ya. Not that it’s hard just sucks being on your back working around Jack stands and cherry picker legs. Keep the progress coming. Nice job so far.


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[Geotrash]

Thank you, snowbound. I was just logging in to give an update and saw your message so I’m grateful.

Finally got the oil pan out this evening and it wasn’t as bad as I thought it would be. I dropped the passenger side of the differential, the stabilizer bar, and the crossmember and steering rack. An air impact wrench makes short work of such things.

Thanks for the advice on the heads. The .0025 number came from another member here who suggested it to get the quash a little tighter for better combustion. Already got them back from the shop, cleaned up and ready to go. Putting the trunnion upgrade kit in this week, and new seals. Valves are all in good shape as well. That’ll about do it and she’ll be ready to start going back together. If I’m lucky, I’ll have her up and running by the weekend.


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[JTRATX]

Are you doing headers/new exhaust, or just re using OEM?

 

[Geotrash]

Are you doing headers/new exhaust, or just re using OEM?

Just reusing OEM


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