Introduction: A simple gesture, maximum protection
After every saltwater outing, your Rotax engine carries invisible but devastating amounts of salt, sand, and marine particles. These deposits accumulate in the cooling systems, exhaust system, intercooler (supercharged engines), and hoses—silently attacking internal components with every passing hour.
Freshwater flushing is the most important maintenance step you can perform on your jet ski or Williams tender. It takes less than 5 minutes, costs nothing, and can save you thousands of euros in repairs. Here's why—and, more importantly, how to do it correctly.
Why is flushing essential?
Saltwater is an extremely aggressive corrosive agent for metals, seals, and technical plastics. Here's what happens if you neglect flushing:
- Accelerated corrosion of cooling liners and exhaust manifolds
- Progressive obstruction of water circuits by lime and salt deposits
- Degradation of seals and hoses due to the chemical action of salt
- Engine overheating over time, due to insufficient cooling
- Warranty voidance: BRP and Williams explicitly state that failure to flush may invalidate the manufacturer's warranty
⚠️ Warning: Flushing must be carried out after every saltwater or brackish water outing, and systematically before any winterization or prolonged storage.
When should you flush your engine?
- ✅ After every saltwater or brackish water outing
- ✅ Before any winterization or prolonged storage
- ✅ When the jet ski will not be used again on the same day
- ✅ After navigating in waters laden with sand, algae, or particles
However, if you make several outings on the same day, a single flush at the end of the day is sufficient.
💡 Pro tip: Always flush the same day, while the engine is still warm, rather than the next day or later. As long as the engine is warm, the seawater remains liquid in the circuits and is easily evacuated by flushing. If you wait, the water evaporates and salt crystallizes on the internal walls of the cooling and exhaust circuits—forming hard, difficult-to-remove, and much more corrosive deposits. Hot flushing = maximum efficiency.
Step-by-step flushing procedure – Sea-Doo & Williams
The procedure below is suitable for Sea-Doo Bombardier jet skis and Williams Sportjet, Turbojet, and Minijet tenders equipped with Rotax engines. Always perform this operation in a well-ventilated area, away from any ignition sources.
- Rinse the jet pump area with fresh water before starting the procedure, to remove external salt and sand.
- Check the raw water filter: open it and clean the internal filter if it contains debris.
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Connect the freshwater hose to the flushing point:
- On Williams 460 & 520: connector located at the stern of the boat, on the jet pump bracket
- On Williams 345, 395 & 435: flushing point located in the helm footwell
- On Sea-Doo: flushing connector accessible from the engine compartment or the stern depending on the model
- ⚠️ Do not open the water tap at this stage.
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Start the engine, then immediately open the water tap.
Important: Always start the engine BEFORE opening the water. Open the water immediately after starting to avoid overheating. Never run the engine without water supply when the boat is out of the water. - Let the engine idle for 90 seconds. Never exceed 2 minutes out of the water—the driveshaft seal is not cooled when the vessel is dry.
- Check that water is flowing freely through the jet pump during flushing. If not, stop and consult an authorized technician.
- Close the water tap.
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Rev the engine to 5,000 rpm for 5 seconds, then shut down the engine.
Always close the tap BEFORE stopping the engine. - Disconnect the hose from the flushing point.
⏱ Total duration: less than 5 minutes. No tools required.
The right equipment for effective flushing
To perform this flush in the best conditions, you will need a suitable flushing connector for your model. We offer connectors compatible with:
- Sea-Doo Bombardier – plastic/copper male or female connector
- Williams Minijet, Turbojet, Sportjet – same Sea-Doo connector (Rotax engine)
- Yamaha WaveRunner – dedicated Yamaha connector
Find our freshwater flushing connector in our store, available in plastic or copper versions, with or without interface.
Conclusion: 5 minutes for years of reliability
Engine flushing is one of those simple gestures that make all the difference in the long run. Five minutes after each outing guarantees a Rotax engine that remains reliable, performing, and protected against salt corrosion—season after season.
Also consult our guide on recommissioning your Sea-Doo in spring and our article on ROTAX error codes: deciphering and correcting a fault code for comprehensive maintenance of your vessel.
