I've been working on a 92 Trailboss 350L 4x and am now at a standstill. Originally when i got it, it had no coolant and low performance. I added coolant and started getting a thick white smoke that smelt of coolant. Figuring it was the head gasket I tore it down to replace it and found the piston had blowby and was heavily scared, though the cylinder wasn't too bad. Never the less, I honed the clyinder and replace the piston and rings and put it back together. Upon my first starting it ran for a few moments but sounded terrible like the engine was dragging. I ran it a few more times and it only got worse. I tore it down again and found water in the rings and lower in the crankcase (in rather large quantities in the crankcase). The first time I tore the engine down I inspected the head and cylinder at length for any type of cracks. I spent days looking at them in different lighting making sure they weren't bad. I figure if it was a hairline crack, how did so much coolant get into the crankcase and around the rings? it seems to me a crack large enough to let that much liquid in in the short amount of time it ran should be visible to someone looking for it. Does anyone know of any other possibilities I may be overlooking here? I'm really at a loss and have no idea how to continue.  

did you check the crankcase where the cylinder bolts on?
it may be cracked.

and check the ports if you haven't already, the coolant has to get in there somehow.

normally it's a cracked head, or cylinder port, but on some models it can be the case cracked where the cylinder bolts up.  

I'll check them all again today and get back to you. Thanks for the reply Wolf.