Lower unit paint/corrosion issues.

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Lower unit paint/corrosion issues.


Post by gandrfab » Sat Feb 02, 2019 12:58 pm

Mercury 4 stroke, 300+ hours, guess 4 years old. Shhhh Don't tell welder this is on a glass boat.

Spends it's life on a trailer when not in use.
Almost exclusively used in Florida salt water. After each use it receives a running flush and a nice wash down then stored under a pole barn.
What can we do to stop this and what are the recommended repairs?

Thanks, Matt
merclower2.PNG (802.65 KiB) Viewed 122 times
merclower.PNG (872.5 KiB) Viewed 122 times

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Re: Lower unit paint/corrosion issues.


Post by welder » Sun Feb 03, 2019 4:40 pm

Did someone say g l a s s ?
Does that lower unit have sacrificial anodes on it?

I would get it cleaned up and repainted ASAP and make sure there are some ZINCS on it .

OK, I looked back at the 1st pic and can see a zinc, looks like it's mot doing it's job.
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Re: Lower unit paint/corrosion issues.


Post by Chaps » Fri Feb 08, 2019 5:08 pm

It kinda looks like the original factory aluminum anodes were replaced with a zinc anode kit which will not adequately protect an outboard motor and shouldn't even be avail on the parts aftermarket IMO. The lower unit housing is lower nobility than the currently installed zinc anodes so the LU housing becomes the anode and the replacement zincs and the ss prop are busy eating it up. At least that is what appears to be happening. Replace all anodes (including the one behind the prop) with aluminum anodes, repaint LU.
1987 24' LaConner pilothouse workboat, 225 Suzuki
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