Took the boat out for the first time this season. (I know, it's the end of June and this is the first time out) Going through the river to get on Lake Michiganqnd the temp was fine. When I got to the lake and throttled up, the temp climbed very quickly. I throttled down and let it idle out of gear for a minute. When I tried to throttle back up, the engine bogged. By this time, the temp was nearing 200. It wouldn't go past idle. I shut the boat off and just floated for a little bit. The temp came back down to normal operating temp, 150ish, it ran perfect, throttled up no problem. BUT, the temp started to climb to 180ish and never higher. All of a sudden, the temp came back down to 150-160 and stayed there so I just idled back to a buddies slip. We later took the boat back on the lake. Had the same result.
1. I had the impeller and water pump housing, etc. replaced at the end of last year and boat ran fine.
2. Could the thermastat be stuck? I understand this happens sometimes during storage.
3. Does the engine have some sort of "shut down" mode when it is running too hot to protect it? The boat only bogged when it was too hot, then ran perfect when the temp came back down.