2010 DENALI 6.2 Motor "Seized"

[Geotrash]

Another update for everyone interested. Pulled valve cover and nothing looked odd, loosened rockers on that cylinder and nothing seemed odd there. Threw my leakdown tester on that cylinder and I'm getting air out the intake only, so fingers crossed piston is intact and it's a head/valve issue yet...and the piston didn't get the piss beat out of it!

Next couple weeks I'll get the coolant drained and start tearing apart and pull the head!

Thanks for the updates. Keep 'em coming!

 

[mikeyss]

I picked up a 2009 Denali In similar condition scenario. Pulled oil plug and coolant came out with the oil. Couldn’t turn motor over with breaker bar on crankshaft pulley. Had to pull engine with transmission together. Pulled the heads and here is what I found, looks like the piston exploded. Taking block to machine shop to assess, but think it can be rebuilt. **Update-looks like a valve seat came loose and caused the piston to implode.***

My 09 had the exact failure you have there, and it's even in the same piston location. I still can't explain why it happened, but I went with TSP performance heads and a 4 corner steam kit instead of going back to stock.

 

[georgerenner]

When you say, 'a lifter', there's two kinds of lifters in GM LStype V8s capable of V4 mode:
one mode lifters (ol' school), and two-mode lifters that allow V4 mode to happen.

Two mode lifters cannot possibly last as long as one mode lifters, even with the most responsible oil change intervals.
Two mode lifters fail often enough, that:
the majority of engine rebuilds replace them with one mode lifters, either as precaution or as a fix
fixing / replacing one or more failed lifters is among the most common reasons to rebuild these engines
Many rebuilt engine vendors sell more engines lacking V4 mode than having it, because it improves longevity and durability

Read your link, interesting. Sounded like Stockholm Syndrome.

 

[georgerenner]

I picked up a 2009 Denali In similar condition scenario. Pulled oil plug and coolant came out with the oil. Couldn’t turn motor over with breaker bar on crankshaft pulley. Had to pull engine with transmission together. Pulled the heads and here is what I found, looks like the piston exploded. Taking block to machine shop to assess, but think it can be rebuilt. **Update-looks like a valve seat came loose and caused the piston to implode.***

Thanks for sharing your efforts!

 

[Rokjhn]

My 09 had the exact failure you have there, and it's even in the same piston location. I still can't explain why it happened, but I went with TSP performance heads and a 4 corner steam kit instead of going back to stock.

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Was just looking at steam vents and wondering if I should put the old one back in or upgrade? What kit did you use?

 

[mikeyss]

There are more cost effective versions here too that look good. But there are also more flimsy versions that use rubber tubing and look like leaks waiting to happen

 

[dyce51]

Got the head pulled today, about what I was expecting. Dropped a valve seat in cylinder 7. I was actually expecting more damage to the head, but the piston got nicked as well...

Other pistons on this side look fine and the cylinder wall isn't damaged. Not sure yet what I will do. May do a leak down test on the other side and see how that comes out. The PCV hose I noticed had quite a bit of oil in it, what does the inside of the "new style" vs "old style" valve cover look like? Not sure if that's where the oil is coming from or not, but it was my first guess with the oil in the hose and intake.

I had a brief thought of "Pull the pan and replace the piston"... but reality set in and that's obviously not the "Best" idea.

 

[j91z28d1]

even the new style valve cover needs a catch can for the amount of oil in the pvc. so I wouldn't worry about that. I'm amazed how much I get every 5k miles or so.


honestly I kinda lead towards the sloppy mechanics way of doing things lol. good youtube if you haven't seen it. if pull the pan and pop a unused piston and rod in is an option, I wouldn't hesitate. mostly the valve train is going to fail on these things before a sketchy bottom end will anyways.

 

[dyce51]

even the new style valve cover needs a catch can for the amount of oil in the pvc. so I wouldn't worry about that. I'm amazed how much I get every 5k miles or so.


honestly I kinda lead towards the sloppy mechanics way of doing things lol. good youtube if you haven't seen it. if pull the pan and pop a unused piston and rod in is an option, I wouldn't hesitate. mostly the valve train is going to fail on these things before a sketchy bottom end will anyways.

I am somewhat considering this...maybe...I'm one for fixing something if it's fixable...to a point. I doesn't look like it hit hard, so I don't believe the bearing or rod will be damaged.

I will assess some more and hopefully make a decision this weekend.

 

[donjetman]

The PCV hose I noticed had quite a bit of oil in it, what does the inside of the "new style" vs "old style" valve cover look like? Not sure if that's where the oil is coming from or not, but it was my first guess with the oil in the hose and intake.

The new improved driver side valve cover makes a night a day difference in what I catch in my catch can. With the original 07 L92 vc I was catching 1-2 oz every 100 miles. With the new and improved vc I catch about 2 oz every 5k miles.

Here's the GM TSB with pics of the valve covers on page 2:
https://f01.justanswer.com/ebrock63...il+Consumption,+MIL+ON,+Engine+Runs+Rough.pdf