Why is my 2004 Sea-Doo GTX running hot or overheating?
My 2004 Sea-Doo GTX has started throwing a high temperature warning after about ten minutes of riding. The engine feels very hot, but I can't see any obvious leaks in the hull. What should I check first?
Answer
A 2004 Sea-Doo GTX overheating is almost always caused by a blocked jet pump intake starving the raw water exhaust cooling circuit or a low coolant level in the closed-loop system. Because the Rotax 4-TEC engine relies on the aluminium ride plate acting as a heat exchanger, any debris disrupting high-speed water flow underneath the hull will quickly trigger a high-temperature alarm.
Jet Pump and Intake Blockages
Unlike older two-stroke jet skis, your 2004 GTX features a hybrid cooling setup. The engine block is cooled by antifreeze in a closed loop. The exhaust system relies on raw sea or lake water pushed by the jet pump. The closed-loop antifreeze sheds its heat through the aluminium ride plate on the bottom of the hull. This requires a constant flow of high-pressure water from the pump.
Sucking up a plastic bag, a clump of seaweed or a heavy load of sand prevents the jet pump from pushing water through the exhaust or over the ride plate. The engine will overheat within minutes. Before turning a single spanner, look under the stern at the intake grate. Always disconnect the DESS lanyard and remove the negative battery lead before putting your hands near the impeller. Pull out any debris. Even a small piece of wood wedged against the impeller blades will cavitate the pump and destroy cooling efficiency.
Check the Coolant Circuit
If the intake is clear, move to the closed-loop system. The 1503 Rotax 4-TEC engine holds 4.5 litres of coolant. Open the seat and check the expansion tank on the starboard side. A level below the 'Cold' line indicates a leak.
Top it up with a 50/50 mix of silicate-free ethylene glycol antifreeze. BRP XPS premix is the factory standard and costs £20 per bottle. If the tank is empty, you must bleed the system of air using the bleed screw on the thermostat housing. Running the engine with air pockets will crack the cylinder head.
If the coolant level is fine, suspect the thermostat. Located in the housing on the top of the cylinder head, it opens at 90°C. A stuck thermostat prevents coolant from circulating to the ride plate. Test it by suspending the unit in a pan of boiling water with a thermometer. Replace it if it fails to open fully. An OEM Rotax thermostat costs £45.