2016 Mojo Overheat

[Casey B]

I took the family out last night to watch some fireworks over the lake. When the show was over we were idling away with a few hundred other boats. When I got clear enough to open it up it wouldn’t go, I checked the temp and it was 240. I shut it off and when I raised the engine lid there was steam rolling everywhere and all the engine coolant was in the bilge. I had a buddy tow us in and helped load it on the trailer ( nothing like loading a 23’ boat with no power). I pulled the impeller today which was replaced in the spring, it wasn’t broken but had taken a big set. I found a small stick in the paddle wheel sensor on the heat exchanger and am wondering if I sucked up enough trash to stop up the heat exchanger? What is the best way to check and clean the heat exchanger and how do I flush the antifreeze system and ensure it is filled back up?

[Casey B]

I checked the raw system today the heat exchanger was clear and I replaced the impeller. I started it on the hose and water was coming out of the exhaust but the engine was still getting hot. I am thinking thermostat or water pump on the engine for the closed system. Do either of these have a history of going out?

[PuraVida]

do you have a heater?

[gcnettl]

Thermostats can and do fail to open. Pretty simple and cheap to replace.

[KnoxMojo]

My Mojo did the same thing. If you have a heater, check your exchanger pump at your transmission cover. The way I checked, fill your coolant tank with water, crank the boat up, look for the leak. It will be pretty visible.

[Casey B]

I did check the thermostat on the stove and it opened at 165 and was clean so that doesn’t appear to be the issue. I do have a heater and noticed one of the lines was a lot hotter than the other. Does the electric circulation pump work off the key switch or only when the heater is on?

[gcnettl]

I agree on the thermostat. I’ve never seen the closed system so I don’t know how they operate.

[Casey B]

I ended up taking to the dealer, after talking with indmar they said to change the coolant. This appeared to take care of the issue, thankfully it wasn’t something major.