Engine advice

[levi20AE]

So my truck has been smoking some blue/gray smoke on start up and a noticeable amount under light load.  I did a compression and leak down check a few months back and all the cylinders were:
500 550 475 500
7%  4%  6% 8%
so i assumed the blue/gray smoke must be from valve guides and seals.  I would occasionally get a stuck exhaust valve that would always work it self free after a second, generally before I would have time to figure out what was happening.  This also lended itself to my hypothesis that the smoke was from worn guides and seals.

So i got a head back from the machine shop last week with new seals, guides, valves, keepers, and a fresh valve job to the seats.  I was planning to put it all back together tonight but i found some semi concerning things in with the existing block and pistons. 



All of the pistons have what looks like hot spots from pre-detonation just below where the prechambers evacuate into the cylinders.



Also the block looks to have suffered the same fate on cylinder number 4.  The hole in the head gasket for the water passage was swollen shut nearest this part of the cylinder so i am assuming again that this was a hot spot due to no coolant flow.



I was hoping to get by with putting this new head on the truck and running another 210k miles but now I'm second guessing.  I dont really see and cross hatching left on nay of the cylinders but i also don't see any scoring. I was thinking if the cylinder walls were overly worn then the blue gray smoke could be the result of blow by from the rings but then the compression and leakdown numbers shouldn't be so good, right? Do you guys think this block is tired and near done or does this look normal for this many miles?  I thought about getting new pistons and honing the block but certainly needs to come out get re-cut for oversize pistons if i wanted to go that route. 
 
Here are some pictures of the new head and engine just before disassembly.






Thanks

[vanbcguy]

The piston damage is most likely a result of worn injectors.  That said, they are in no way substantially damaged, if you look through the various pics of engine teardowns on here you'll see quite a few that are worse than that.

The damage to the block likewise appears pretty minimal to me.  It doesn't appear to extend into the ring sealing area so it shouldn't cause an issue.

I'd personally go with that gorgeous looking head and a fresh set of injectors, considering the compression / leakdown numbers you have.

[Mark(The Miser)UK]

Forget the block and pistons. They are fine.
Was there a check done on the valve stems/sleeves for wear?
I think you were correct with the valve stem/seal issue. perhaps amplified by  the above wear.
Reassemble and drive away...

[levi20AE]

i haven't checked the old head to see how bad the wear actually was. I use the truck as my primary mode of transportation so i went ahead and got the head completed before taking the old head off the truck.  Im glad to hear that you guys feel good about the block.  I was gonna toss the head on it and start searching for a new block but it sounds like the motor still has lots of life left in it.

Thanks guys.

[nathan_b]

lol, predetonation.... not really possible here..

[R.O.R-2.0]

lol, predetonation.... not really possible here..

kinda what i was thinking 

you can get pre-detonation if you run too much propane or CNG cant you?