How Did This Happen??????????????????????
 

Here's what happened, I bought a 1998 Chevy K3500 6.5L turbo diesel last December with a rebuilt engine that had been installed but none of the ancillaries had been fitted & it had sat like this for approx 4 years. So I put the puzzle back together & everything ran fine for 800 miles then out of the blue, bang, bang, bang she started knocking. I shut her down straight away & tore her apart and found #1 intake in pieces.
Whats remains of the intake valve looks like crystallized sugar around the edges & apon further inspection it appears to be happening to some of the other valves.
Has this happened to anyone else?
What could have caused this to happen?
Don't want to fix it & have it happen all over again.

Ouch! I'm not sure what would cause that.... Not good. Hope someone chimes in......