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Combat Corrosion

Modern outboards usually corrode before they wear out. Here’s how to prevent that from happening

Capt. Merritt White 

Long Island Fishing Charters

I’m a fishing guide on eastern Long Island. My 21-footer has 6,000 hours on its 150-hp Yamaha 4-stroke, and I expect to get a couple more years out of the motor. My secret to fighting corrosion? Rinse, rinse, rinse. Flush the motor after every use with fresh water. I don’t use any additives. Rinse the outside of the motor, and try to get under the mount where the tilt motor lives. On a trailer, you have complete access. Replace the anodes when necessary. I change the oil religiously, every 100 hours, and at every oil change I pull the cowling and wet down the engine with CRC.

Tim Reid 

VP, Mercury Marine

Your outboard continuously draws water in, circulates it around high-heat components to cool them, and then discharges the water. We recommend flushing after use in salty, muddy or contaminated water because deposits can cling to inside passages and break down those surfaces at a molecular level. Plus, flushing helps to prevent clogs that could impede the flow of coolant water. The flushing port on Mercury outboards makes this easy. With the engine off, trim it to the vertical position, attach a freshwater hose, open the spigot halfway and flush for 15 minutes. 

Glenn Bennett

Bennett Marine, New York

On my own boat, a 25 Mako, I have a 2009 Evinrude 250 E-Tec with about 360 hours on it. Whenever I use the boat, I flush the engine for 15 or 20 minutes with fresh water. Twice during the summer, I pull the cowling, check for rust or corrosion, and spray everything with CorrosionX. I change the fuel filters at the same time, and I use an additive in my fuel because of the ethanol. My yard workboat has a 1996 Evinrude 150. It doesn’t get flushed after every use, but it’s running fine with more than 2,000 hours. At the end of the season, I flush it, fog it and spray with CorrosionX.

Bill Lindsey 

VP Marketing, Star brite

I flush my outboard with Star brite Salt Off after a day on the water. It’s cheap insurance. I do this right away, while the engine’s still hot. The thermostat needs to be open to ensure Salt Off flows through the engine. On the trailer, I run the engine until it reaches normal operating temperature. Then, I shut down. I attach one end of the Salt Off applicator to a garden hose and the other end to my motor’s flushing unit. I fill the applicator cup with Salt Off, turn on the water and allow it to run. When I see only clear water in the applicator cup, I know the engine is flushed.

This article originally appeared in the June 2019 issue.



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