Good eveniing, if the crank pulley and balancer moves in and out then the thrust bearings are worn out. This can cause the internal noise and also cause the flywheel to contact the back of the block as well. Here is some info about possible noises and causes. As you can see, main bearing noise can be caused by excessive wear on the thrust bearings:
Here are the actual specs for the end play (in and out of the crankshaft)
Any thing more than 0.010 in. requires extensive repairs such as crankshaft and bearing replacement and possibly even engine replacement.