Recently had my radiator replaced r/t leak on bottom of it. Ran fine until recently when it suddenly started
clattering on the valve train & gray-blue smoke was coming out from underneath the van. turned out the oil filter was loose & spraying oil all under the van hitting the exhaust & causing the smoke, but noticed it was low on coolant-water & as fast asI replaced it, it kept disappearing. Decided to stop filling it & change the oil filter & oil. When I did found out where all the coolant-water went. drained all the oil & water from the crankcase. Here's my question. Is there any way coolant-water can get into the engine other than a blown head gasket(s).

 

that is the most common way that coolant gets into the crankcase oil. do a compression check on the cylinders.I have seen cracked cylinder sleeves but rare. from your description of various problems, i would put money on a warped cylinder head. Sorry.