Engine will not turn by hand

There is no sure why to do this. How long was the water in the engine? Are you saying that the engine is rusted because it sat with water in it or have you drained it out and now the engine just won't turn over?

In other words, is this days, weeks, or months with water in it? Clearly the longer it has the water in it, the less likely you will free this.

The only way I have been able to free a locked engine was using a penetrating oil and adding it to each cylinder and I mean a lot of it in each cylinder. Then let it sit overnight. After that, take the starter off and use a large pry bar on the flexplate teeth to start working it back and forth. As it frees up, you can move more and more. This may take a few times meaning, soak it again overnight. Then rock the flexplate again and again until it is able to be turned with using a socket on the crank bolt.

Let us know how you make out. I am sure when some of the other guys read this they may have ideas as well.

If I understand correctly the water was in the engine and then drained out shortly after but the head has been off and in its current state since the end of winter?

If this is the case then it may be locked up for good. Basically rust can start to grow overnight on exposed metal components which is what the internal engine components are.

What is the current state of the engine? Do you have the head off of it right now? If so, you can try and shock the pistons with a metal mallet and pipe to try and break the rust loose and then soak them again before trying to turn the engine over again.

Basically you put a pipe on the piston and then give the pipe a hit with the metal hammer. Clearly you don't want to do this too hard or you will damage the piston. Again, you just want to translate that shock to the rings as they are most likely rusted to the cylinder walls.

Hopefully you can get this free. Let us know what you find. Thanks