Outdrive corrosion?

[SavinRaven]

this was after just 8 weeks in fresh water... there was some minor spots like this but now it's just covered.. always had mercruiser and never had this issue. This is a Volvo SX. Ideas on how to stop it from happening and how to fix it already? I'm sure it's not good for the outdrive..

 

[Chris1956]

You might have this moved to the V-P section. If that is galvanic corrosion, you likely need some anodes and test for some current leak into the water,

Was the paint factory applied, applied by you or someone else?

 

[SavinRaven]

I'm only the second owner and have only had it this season but I believe it is factory.

 

[harringtondav]

Your anodes appear to be good and in place.
Interesting that the plastic cover on the rear of the upper gear case is loosing its paint. ....plastic doesn't corrode. So my guess is the previous owner repainted with spray can paint which doesn't hold for long.
If you're up to it, this forum has recommendations for repainting using the several steps and coatings used by the factory. I've read these in the Mercruiser section. Maybe the VP section has the same.

 

[Grub54891]

I'm not seeing the anodes in the pic. And the rusty cotter pin on the prop should be stainless.

 

[harringtondav]

I'm not seeing the anodes in the pic. And the rusty cotter pin on the prop should be stainless.

Pretty sure I see the anode on the leading edge of the anti cavitation plate. Also it appears to be a steering trim tab vs the anode disc. ....assuming this is sacrificial, made from anode material.

 

[tank1949]

View attachment 365683

this was after just 8 weeks in fresh water... there was some minor spots like this but now it's just covered.. always had mercruiser and never had this issue. This is a Volvo SX. Ideas on how to stop it from happening and how to fix it already? I'm sure it's not good for the outdrive..

is boat moored next to other boats? Are they having similar problems? Some other boat may be causing this crap due to producing stray currents.

 

[Grub54891]

Pretty sure I see the anode on the leading edge of the anti cavitation plate. Also it appears to be a steering trim tab vs the anode disc. ....assuming this is sacrificial, made from anode material.

Yup, my phone didn’t show it to well.

 

[Scott Danforth]

Looks like galvanic corrosion.

Maybe get one of these while you are moored at the marina

https://www.amazon.com/Martyr-Aluminium-Grouper-Hanging-Aluminum/dp/B001TKAR8A/ref=asc_df_B001TKAR8A/?tag=hyprod-20&linkCode=df0&hvadid=312141063266&hvpos=&hvnetw=g&hvrand=9813709898179090235&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9012287&hvtargid=pla-490245344586&psc=1