Have Boat Questions? Ask a Boat Repair Expert.
Hi and thank you for your question.
There are 2 overheat warning systems on each engine. One is for the engine overheat and the other is for an exhaust overheat. Do you know which warning you are getting?
Also, did you happen to notice that while underway, meaning NOT on the flush kit, and when the overheat warning came on were you getting water out of both of the pilot outlet ports on the side of the hull?
Also, for the sake of accuracy, what exact year is your boat?
Thank you for the additional information.
This sounds like you have a blockage or restriction in the cooling line between the jet pump and the "Y" joint where the flush kit attaches. Think about that Y as laying on its side with the two legs pointing towards the rear of the boat. The cooling water from the jet pump comes in on one side of the Y and the flush kit comes in on the other. I saw that you stated on the flush kit the engine seems to operate normally. That is a good thing and it also helps us pin down the probable location of the problem.
The best way to attack this is to trace the hose from the flush kit down to the Y and disconnect the hose that is on the other half of the Y. The single end obviously goes to the engine and components for cooling. The point I am trying to make here is to ensure you get the correct hose that is coming from the pump. Once you locate the Y, disconnect the hose and blow through it towards the jet pump. You can use a compressor, but don't hit it with full pressure right off the bat. Try to just bleed a little pressure into the hose at first, to see if you can detect a resistance to flow. Once you get a feel for it, go ahead and increase the pressure. This should clear the line for you. It is quite possible either you have a stick, sand, a shell or something like that lodged in the line.
Let me know if you need any more help.