Help with zinc selection

ccm14

Cadet
Joined
Jun 15, 2011
Messages
22
Hi,
I have some corrosion on the lower unit of my 2006 Yamaha F150 and while researching my options for the removal of this corrosion I ran across some posts about zinc's so I have started to wonder if I have the proper zinc's on my motor and could that contributed to my corrosion. It is my understanding that "freshwater = magnesium, brackish = aluminum, salt = zinc" but I use my boat in both fresh and saltwater. Don't know if it matters but I have a stainless prop.

The zinc on the outboard shows very little corrosion and has never been replaced.

Two questions:
How do I tell what type of zinc my motor has now?

Considering the fresh and saltwater use, what zinc should I use?

Thanks in advance for your advice.

Charlie
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Help with zinc selection

You could remove the zincs on the lower bracket and the trim fin zinc, clean them both with a wire brush and replace good and tight. Where the zincs bolt onto the motor should be wire brushed also, since it is essentially an electrical connection. No paint or grease on zincs so they can easily do their jobs as the sacrificial anodes. My motor is a 1999 model and I've never replaced the zincs, I run in fresh, brackish and saltwater, I'm not sure what metal they are but they have some minor pitting on them. Some corrosion on an outboard lower unit is not that unusual....brush it off and touch-up paint it. Good Luck!:)
 
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