I have a 2003 Mercury 150 hp that I use in saltwater. When run at low speeds, it runs great. When I go to full throttle, the engine temps spikes to about 250 degrees. After throttling back down it goes back to 170 degrees. It has a good flow of water comming out, but when you touch it, it is boiling hot. I am leaning towards a possible clog in a water line, thinking that it is only able to circulate a small amount of water thereby not cooling at high speeds. Any advice or help would be of great help. Thanks
