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2008 GMC Envoy Denali

Yesterday was tear down day for the engine. Since the engine is seized I couldn’t disconnect the torque converter from the flexplate before removing the trans so I just pulled the trans, leaving the coverter attached. Once the trans was off I could reach down between the block and flexpate to loosen the torque converter bolts. Then I lifted it onto the stand.

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The front two exhaust manifold bolts on the passenger side were broken. Once the manifolds were off you could see a definite exhaust leak.

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Next I started tearing down the top end. First thing that came off was the valley cover, which is the brains for the Active Fuel Management.

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Next were the valve covers. I first had to remove the coil packs. Oops, I see in the pics this was actually before the valley cover.

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Once in the valve train I found some of the pushrods and rocker arms were worn so I’ll be needing to source those when it comes time to build an engine up.

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It’s hard to see in the pics, but this one is worn
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This one still looked normal.
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With the heads off I could start to get an idea of the condition of the block. To my surprise the cylinders were still in good shape! The coating on the pistons must have helped save the liners. A couple cylinders have some weird discoloration (reminds me of a calico cat), I’m not sure what that means, but I’m guessing it is caused by heat.

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The heads have a bit of carbon in the chambers from the oil consumption.

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Time to flip the engine over. I could finally get a good look at what had been a puzzle in my mind: the engine-mounted front diff. Luckily I had my new service manuals to guide me here. It’s actually pretty simple. On one side is the differential.

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And on the other side is a bearing that supports the end of the shaft that passes through the oil pan and the CV axle.

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Here is an exploded view of the parts after removal.

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It’s just a tunnel through the pan, no open passages into the engine.

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Now onto the mains (oh before this I removed a plate on the back of the block that seals the back of the cam and holds the rear main seal). You can see in this view that the front 2 rods are a different color from the rest, hmmmm (foreshadowing!).

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Surprisingly the main bearings actually looked pretty good.

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This is where it got exciting - removing the rods and pistons. I still couldn’t rotate the crank, but luckily 3 of the rod bolts on the 1 & 2 rods were easily accessible so I loosened those. Once those were loose I was able to rotate the crank enough to get the 4th rod bolt. Here’s what I exposed....

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What a mess!! The bearings are fused to the journal.

As I worked further from the front of the engine the rods looked much better. Here’s the #4 rod, much nicer although not 100% perfect for sure.

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And here’s #8. Quite a difference from #1 to #8.

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Oh I forgot to mention that when I drained the oil pan I bet only 1 quart of oil drained out! Major oil starvation going on here. Good news is that the block is still usable, which is good because it’s a rare-ish aluminum 5.3 block - good for a turbo build in a lighter weight vehicle. It’s nice working on a light engine for a change.....I could easily hold the block up with 1 arm while I unbolted it from the stand - no cherry picker needed.

No pictures of the last step, but I tore down the cylinder heads to inspect their condition. Luckily the guides and valve stems are still in good shape. This is great news because I hoped to be able to use these heads - they’re essentially the same cylinder head that was used on the 405hp 5.7 Corvette Z06 and are a good head to use on a 6.0 LQ4.
 
Never seen a oil pan like that. Crazy what the car manufacturers come up with to make things work.

By the looks of them bearings I’m willing to bet the PO herd a noise and just kept driving around until the noise finally stopped one day. Looks like the PO was one of them people who bought it and never checked or changed the oil in it. Just kept driving wondering what is that noise I’m hearing.
 
Never seen a oil pan like that. Crazy what the car manufacturers come up with to make things work.

By the looks of them bearings I’m willing to bet the PO herd a noise and just kept driving around until the noise finally stopped one day. Looks like the PO was one of them people who bought it and never checked or changed the oil in it. Just kept driving wondering what is that noise I’m hearing.
Yes and no. I bought the truck from a friend of the family that owned it so I have some of the history of the truck. And I also got a Carfax so I have a little more history. The truck was bought by a couple and driven them for a lot of its life....then they gave it to their son. For most of it’s life it was serviced at a dealership so the drivetrain and suspension were maintained really well. I can even see where the oil was changed at an oil change place about 4000 miles ago. I think the complication is the AFM. Over time these engines like to use oil because of the cylinder deactivation. Unless someone knows this and changes and monitors their own fluids they won’t know that their engine is dangerously low on oil. So the PO was just a typical hands-off owner. This works out for me though - I got a nice truck for cheap and the money I saved can go to drivetrain enhancements :cool:
 
I get this weird sense a combo supercharger/CAC are in the plans too or?
I would love to, but not in the immediate future. I would live to figure out turbo plumbing, but everything is so cramped that I’d have to move too many things for it to be viable right now. That’s why I’m going 6.0 - to get more bottom end torque, naturally aspirated.
 
I would love to, but not in the immediate future. I would live to figure out turbo plumbing, but everything is so cramped that I’d have to move too many things for it to be viable right now. That’s why I’m going 6.0 - to get more bottom end torque, naturally aspirated.
the GM supercharger w/CAC is just a bolt on no figuring anything.....you know you want it.
 
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