I was recently given an older Sailmaster 4 (I think about a 1974) that's not been used much. Cylinder head is a bit brown, I think from overheating. I put a new fuel pump and rebuilt the carb, and it started right up. However, it didn't run long before I could feel the heat. I've since taken it apart a couple more times and made sure everything was lined up OK, but it still runs too hot. Today when I took it apart again, I tried to blow through the tube that goes into the water pump, and no air moves at all. Should it? I can't find a thermostat on this, so maybe it's plugged up. If it is clogged, is there an easier way to get it unclogged? Thanks