By Adit Marine · Cleaning & care
First confirm which system you have
This article describes Adit Marine's hose-fed engine-flushing routine. It is not a universal procedure for every generator, air-conditioning circuit, Bluetooth tank-fed installation or chemical treatment. Confirm the installed system and use its operating instructions, including how its water supply and controls are managed.
Before beginning, secure the boat and inspect the visible equipment. Do not start flushing if you have an unresolved leak, cooling alarm or concern about the installation. Arrange a competent assessment instead.
Connect first, then run the engine
With the engine off, connect the freshwater hose at the designated flush point. Then start the engine and follow the system's instructions for the water supply and controls. Flush the running engine for 1–2 minutes.
Keep the seacock open before and throughout flushing. Remain with the system, monitor operation and stop if something appears abnormal. Connecting a hose is not a reason to ignore the normal cooling indicators or leave the boat unattended.
Finish with the engine-off backflush
Stop the engine, then keep fresh water flowing for a further 10–20 seconds to backflush the sea strainer. The seacock remains open during this stage. Complete the installed system's shutdown and hose-disconnection procedure afterwards.
Do not confuse this operating sequence with installation work. Opening raw-water pipework to fit equipment requires a separate, appropriately isolated installation procedure carried out with the engine off. Follow the installation instructions and use a qualified installer where needed.
Make it repeatable, not automatic
An accessible remote inlet makes it easier to include flushing in the end of your trip. Keep it alongside your after-use inspection rather than treating it as a replacement. Check for moisture, changed hose positions or anything that needs attention, and record any issues.
Fresh-water flushing is also different from removing established mineral deposits. For an older boat or an uncertain service history, ask about assessment and a compatible initial CFS treatment using the CAD. Do not introduce chemicals using the rinse timings in this article; chemical treatment has its own instructions.
A good routine is one you understand and carry out consistently. Keep the instructions aboard, make sure anyone helping you knows the sequence and seek advice if the actual installation does not match the procedure described here.
Key takeaways
- Connect the freshwater hose with the engine off, then start.
- Flush for 1–2 minutes; stop the engine and continue water for 10–20 seconds.
- Keep the seacock open throughout this flushing routine.