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

 

[dyce51]

Quick update! Got the pan pulled last night and pulled piston out. Cylinder wall has no damage so ordered up the correct OEM replacement piston, got a head lined up (will be gone through and surfaced) along with the gaskets and hardware I'll need ordered. I did order a new rod bearing since it's cheap, not sure yet if I will replace the old one or not. It looked good, but if I'm in there and knowing that there was contact between piston and head via a seat...might be good insurance.

I did verify the motor has the later style valve cover, along with the shield on the AFM Relief in the pan. I ordered up a catch can to add while I'm at it.

As I get it put back together, I will keep the updates coming!

 

[dyce51]

Been almost a MONTH! Back for an UPDATE!!! Slowly over the last few weeks got my parts in hand and motor back together. Went back together fairly well, for being in the vehicle. Not ideal, but it worked. Busted the crappy heater hose quick connects at the firewall so replacing those today. Also chasing p0206:00 injector code...swapped 2 around to see if it follows or not and will dig into it more once the heater hoses are back on.

Will see long term how she holds up. Have a trip early June I would love to take it on, so want to get some good miles on it here the next month to work out any bugs.

 

[dyce51]

Heater hose connections are all fixed up and my injector code/misfire sorted out! At this point, I'm calling it case closed! Added up receipts and I got it done for right around $1200...considering I bought this with plans to swap the motor thinking it was toast...I'm pretty happy!

Going to drive it and hopefully work out any other issues that come up. Going through the history, brakes have been done less than 20k miles ago, trans was replaced around 50k miles ago...so may be due for a flush before to long, front end was gone through in the last 50k miles...so quite a bit of major work was done that I would normally be looking at doing.

One thing I didn't see in the maintenance history was differential fluid changes...so I may do that before our trip in June.

One thing I am curious on...in our other rig (2013 with a 5.3)...we run E30 quite often vs E85 as mileage seems to be much better and it's a decent price, anyone had any experience running the E30 in these rigs..."Supposedly" the octane rating is supposed to be between 92 & 94...depending on ethanol content...

 

[Just Fishing]

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.***

This is why you run premium and not regular in a 6.2.