The 4Tec is not a ski you want to overheat. The cooling system to the engine block is closed (uses a coolant mix) and the cooling system to the exhaust is open (uses lake water). If your exhaust is overheating, check your pump for debris as this is where the lake water enters the system. Make sure all your cooling lines to the exhaust system are clear. As far as the closed system, make sure you have the proper mix of anti-freeze/water and that the system is full and purged of air. The coolant circulates through a heat exchanger on top of the ride plate so the heat is only disipated when the ski is moving. Be very careful about running a 4Tec on a flush hose. The exhaust is the only part that is cooled by the flush system.