I've been helping a friend troubleshoot this issue for probably 5 years now. He has replaced the impeller and housing multiple times, new popit, and new thermostats (2x). The boat always seems to run fine until we start wakeboarding. Even if we are not falling, the boat still overheats and the buzzer turns on. At idle for ~30 sec the buzzer will turn off. We tried going wakeboard speed without a boarder and it didn't buz. Then we tried going a bit faster with a rider and not cutting (just riding straight outside the wake) and it was fine for ~10 min so we started cutting pretty hard without issue. that was going about 25 mph vs our normal about 20 mph. I read some things that these engines will start to suck air into the cooling system when you are at plow speed (~20 mph with a boarder) where it rides a bit nose high, and you have to mess with the throttle to keep it on plane without accelerating, or coming off plane. We removed the thermostats, and it seemed to get worse and would buzz even without a boarder. We also noticed water coming out the weep hole on the popit. I've seen some people mention adding a water pressure gauge but I didn't find anything. I have also seen people say that they replace the impeller every year. I've been around boats my entire life and that seems crazy. His boat is in a fresh water river and has most definitively sucked up some of the fine sand over the years. I think a full flush with no thermostats or popit would be wise, but I'm not sure where to shoot the hose water in. If someone has some info on what we may be overlooking, or any advice that would be much appreciated.
