Just a follow up on this in case it helps anyone out. I got a new heater pump and replaced the cracked one, drained the coolant out and replace with new coolant(since i was at 300+ hrs). I followed the instructions from Indmar. Spent a few hrs on the lake last week and the engine temp stayed nice an constant around 160. After leaving it overnight I checked the level in the coolant tank and it was a bit low so i topped it off. Everything seems to be great now.