I know the reply is late but, if you haven't fixed it yet, the rattling in the crank case may be caused by one or some of your connecting rods being loose on the crank because of a warn out bearing(s).
As for the starter not engaging, it might be a problem with your solenoid. It's often just a small electro-magnetic cylinder that pushes the starter drive into the flywheel of the engine. I've seen people fix this by simply knocking on it with a hammer while starting. opening it up and cleaning it/checking for loose connections is probably a better solution.