How to Flush an Outboard After Salt Water

Outboard makers call for a fresh water flush after every use in salt water. Salt dries into crystals inside the cooling passages. Over time they block water flow, and the engine overheats. Flushing takes a few minutes and is the best habit a Hawaiʻi boat owner can have.

Two ways to flush

Flush port (most newer four-strokes)

Many engines have a garden hose fitting on the lower cowl or under the cowling. On most of these you flush with the engine off: connect the hose, turn the water on, and let it run for the time your owner's manual gives. Check your manual: a few models must be running.

Flushing muffs (ear muffs)

Muffs fit over the water intakes on the lower unit. The engine must run at idle while you flush, so:

• Turn the water on fully before starting the engine, and keep it on until the engine is off.
• Check the tell-tale stream right away.
• Run at idle only, in neutral.
• Keep people clear of the propeller. Removing it first is safest.

Other good habits

• Rinse the outside of the engine and the steering with fresh water.
• Tilt the engine down after flushing so water drains out.
• Spray electrical connections and linkages with a corrosion protectant now and then.

Even with good flushing, salt still builds up. Our yearly service includes the water pump impeller, thermostat check and a look at the cooling system.