Suzuki: water in the engine, manifold gaskets, head gasket

Question
I have a 1990 Suzuki sidekick that in the past december pass water inside the engine, so i change the head gasket and valves. after i start the engine again less than 10 minutes later start to pass water again  a lot of white smoke appear, and all the oil cap was full of water with oil.
so i decided to buy another engine i have been putting like 5 diferent used engines and the same problem appear to all of them. i will like to know what i am doing wrong.
before i get the engine i chek the oil cap and i open the head cap to see if there a mark of water inside also the oil that is inside the oil filter doesnot came with water but when i put the engine inside my car after 3 o 5 minutes the smokes starts again and again.

Answer
The major question is whether the intake manifold gaskets are leaking.  If they have been changed to new ones with each engine swap, and the intake is the same one as the original motor, I would carefully inspect the manifold.  The probability of getting that many defective motors is very remote, and there is some other part or procedure that is common to all these failures.  Carefully examine your procedures and parts.  It is possible that not all the manifolds are identical, or that the hose connections may be introducing water into the engine.  That's my suspicion.
scotty