whatever it is. the motor needs to be removed and torn down for a rebuild. simple as that. driving it/running it is only going to make it worse. and more expensive, because you might throw a rod through the block which means youll need rods and block. if not already. so basicly pull it quick and get it over with. might just need some machine work on the crank and some bearings. vs.... crank block rods pistons cam valvetrain... you know a crate motor.