There is some water in the rear rotor housing. Is it normal for engines shipped from Japan to have some water in the housing? Or is this an indication of a water jacket failure? Also, what size is the nut on the eccentric shaft (in the harmonic balancer)? It's definately bigger than the 13B nut.

 

Is the water green? If not, it could simply be from their pressure washing. Do you have any way to pressure test the water jacket of your engine? Try cranking an air compressure down to about 13-15PSI. Then block the upper and lower waterpump hoses. Then connect the heater core tube on the rear plate to the compressed air. If you hear any air flowing from the rear rotor housing, then the water jacket or coolant seals are toast.

There is no harmonic balancer on a rotary because it dowsn't need one (no pistons boinging about). What you're describing is the 32mm cap nut on the front of the eccentric shaft. The only way I could get mine off was to purchase a 32mm impact socket and lock the flex plate (bolted to one of the bellhousing bolts with some angle iron or something) to prevent the engine's internals from rotating. After some rat-ah-tat-tatting on the nut, it came off. I had already tried fellow forum user now's trick, and was unsuccesful. The impact wrench worked pretty well. The 13B one is a bolt and is 19mm.