How to Clean and Flush a Honda Outboard After Salt Water

Step-by-step instructions

Step 1: Identify the engine and its flushing method

Read the model plate and open the matching Honda manual before attaching a hose. The BF115D/BF135A/BF150A instructions use the engine’s flush-port connector with the engine stopped, whereas some smaller or older engines use another route. Do not combine procedures, cover water intakes unless the exact manual says to, or assume that earmuffs and a flush port are interchangeable. Put the boat securely, lower the engine as directed, and keep the ignition unavailable while working near the propeller.

Step 2: Rinse loose salt from the exterior

After the engine is cool, rinse the cowling, bracket, gear case and accessible exterior with clean fresh water. Honda advises washing after use in salt or polluted water and keeping water out of the air intake. Use mild biodegradable detergent on persistent exterior soil, then rinse it away rather than allowing concentrated cleaner to dry on paint or rubber. Avoid pressure washing seals, electrical connectors and labels. Salt crystals should be floated off, not rubbed across a glossy cowling with a dry towel.

Step 3: Connect the documented flush port

For the BF115D/BF135A/BF150A example, disconnect the fuel hose where the manual directs, tilt the motor down, remove the flush-port connector and screw that connector onto the garden hose. Confirm that the sealing pieces remain present and undamaged. Remove the emergency-stop clip so the engine cannot start while someone is near the propeller. Keep the engine off for this particular flush-port procedure. A different Honda model may explicitly require neutral running, propeller removal and visible cooling-water flow instead.

Step 4: Flush for the full specified interval

Turn on a steady fresh-water supply and flush the example models for at least ten minutes, following the owner’s manual. Watch the hose and connector for leakage without reaching near moving hardware. Do not start an engine whose manual specifies a stopped-engine flush, and never run any outboard without the water supply required for that method. If water does not follow the expected path, stop and check the connector, hose and instructions rather than increasing pressure or improvising a blocked-intake arrangement.

Step 5: Reconnect and drain correctly

Turn off the water, disconnect the hose, and reinstall the flush-port connector exactly as it was sealed. Let trapped water drain in the position Honda specifies before tilting or storage. Confirm that the emergency-stop clip, fuel connection and any removed pieces are restored only when the cleanup is complete and the area is clear. A loose flush connector can become the next operating problem. Do not store the hose attached or leave an open port exposed to insects, dirt or accidental impact.

Step 6: Inspect paint, anodes and exposed hardware

Once clean, look for chipped paint, corrosion, damaged rubber, loose fasteners and abnormal deposits. Honda’s maintenance guidance calls for touching up damaged paint and protecting areas that may rust with an appropriate corrosion inhibitor. Keep wax and protectant away from anodes, belts, controls and surfaces the model excludes. Cleaning is a chance to observe an anode or propeller problem, not permission to grind oxidation from it or perform an unlisted coating treatment.

Step 7: Dry, store and document the next service

Wipe accessible surfaces dry with a clean soft cloth and store the outboard as the manual requires. If moored in salt water, Honda recommends tilting the gear case completely out of the water when conditions and the model allow. Record the rinse and any corrosion found. A freshwater flush removes salt and debris but does not replace gear-oil, anode, impeller or scheduled engine service. Persistent weak telltale flow, overheating or corrosion needs diagnosis rather than another stronger chemical wash.