I had a head gasket blow on my 6.2L. I am pretty sure the reason that it died was due to someone using a bunch of starter fluid to attempt starting the engine when they didn't realize it was the MFI pump solenoid that the issue (was not me, but I am at fault for not supervising I guess).
With the head gasket blown, there are many indicators you can look for. I had the better half of my coolant in the oil pan and oil 75% the way up the dip stick. (I didn't have any calcifications along he side of the head gasket/block on one side, but did have some on the side that failed). I had full hydraulic lock-up and as a result I had some valves crushed to pieces and engine definitely sounded like it was full of loose nuts and bolts, not too mention the big PLUME of WHITE smoke out the exhaust. The classic death of a 6.2L I am told.
My truck came from the Albany, GA auction.
Anyway, I got a used/non-reman 6.2L from TedG that came from a DRMO lot that he picked up. Some of those DRMO engines look scary as hell to me, but I spent $750+shipping and rolled the dice. He stated that he got it from a company that was contracted to do the engine refresh for the military. Having worked with the military, I know that they will replace a large number of engines at the same time to keep them all current and often toss perfectly good engines. So time to roll the dice!
Engine arrived and I kinda cringed a bit. Basically slathered in fresh black paint. Even painted over the bolt holes that were filled with mud-dobber nests. Regardless, the outside is not so much what matters. What matters is what is inside. It had a good flywheel also. So I dropped it in and got it running last weekend. I haven't driven the vehicle yet because I still have some work left to do. (I have a broken valve stem on front tire, so I am looking for valve stems!)
Engine fired right up and went to a stable idle if only a little bit higher RPM than it should. (need to look at linkages and MFI adjustments). It was a little "tappy" sounding for me, but it has been sitting for a while and hasn't had much lubrication up in the lifter/rocker arm areas for a while so lets see how it turns out after running for a while.
I looked into all that was required to do the 6.5L conversion and decided that was not in my budget ($$$ and time). If I have to do that much work, I will just drop in a duramax but then my truck is no longer mil-spec.
Does anyone have any info on this #8 cyl modification? I guess you run a coolant line back there and remove the small cover to install it?