Water in Walter v drive

So we purchased a boat through auction and it was not winterized. After replacing the engine, I noticed the v drive had water in it. I changed it. Drove it. Had water in it again. Took the cooling coil out and vacuum tested it, held pressure. Got water again. I'm new to inboards and v drives but I've read that these things are damn near indestructible. I have yet to lay an epoxy on the base of the cooling housing. I'm going to try that next. Does anyone else have any insight that may help me?