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Lower unit paint/corrosion issues.

Posted: Sat Feb 02, 2019 12:58 pm
by gandrfab
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

Re: Lower unit paint/corrosion issues.

Posted: Sun Feb 03, 2019 4:40 pm
by welder
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.

Re: Lower unit paint/corrosion issues.

Posted: Fri Feb 08, 2019 5:08 pm
by Chaps
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.

Re: Lower unit paint/corrosion issues.

Posted: Tue Feb 19, 2019 1:16 pm
by gandrfab
What does AAB recommend for paint?

Re: Lower unit paint/corrosion issues.

Posted: Thu Aug 06, 2020 2:37 pm
by gandrfab
gandrfab wrote: Tue Feb 19, 2019 1:16 pm What does AAB recommend for paint?

Back to the top. This still could still use cleaning and painting.

Re: Lower unit paint/corrosion issues.

Posted: Thu Aug 06, 2020 2:40 pm
by gandrfab
merclower.PNG
merclower.PNG (872.5 KiB) Viewed 2486 times
merclower2.PNG
merclower2.PNG (802.65 KiB) Viewed 2486 times

Re: Lower unit paint/corrosion issues.

Posted: Wed Oct 28, 2020 8:17 am
by gandrfab
Update: May have been the wrong anodes and a broken jumper wire.
Sanded, painted, replaced anodes and jumper wire.
Seems to be doing well, I haven't looked at it.