# white crusted,pitted outdrive



## little d (Dec 10, 2008)

So i pulled my boat sunday and wow! I was going to replace my gimble bearing and u- joints and now the outdrive is terrible ( need new one ). I would like a new or used case i dont think sandblasting and painting is worth it. Its a 95 bravo II outdrive. Need some help on this one guys. thanks dan


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## Iowa Dave (Sep 27, 2009)

Sounds like your zincs are not doing their job.


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## igmire01 (Sep 13, 2009)

If I remember right, there is a boat junkyard in Michigan. Not too far from the Ohio border. The guy was on craigslist a while back advertising with pictures all he had. He had tons of stuff. Racks of outdrives if I remember right. You may want try looking there first. If I happen to remember his business, I will let you know. Sorry I can't be of more help.


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## roger23 (Mar 7, 2007)

you better check your anodes or the new one will do the same,,are you hooked to shore power?


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## little d (Dec 10, 2008)

Thanks guys ill try to get the boat junkyard #, as i found bravo II outdrives for $5995.99 no way! I am not hooked up to power but the boats around me are. I replaced last year 3 anodes on the outdrive,2 on the trim tab plates and added a 3x6 one on the hull to the batterys and the outdrive housing inside the boat. Replaced my merathode system last year also. I think most of the damage was done before i got the boat as someone bottom painted the outdrive? I would like to find someone that we could pull it apart and try the sandblasting. thanks again im going post pictures also


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## little d (Dec 10, 2008)

Ok guys, here's some pictures if this helps.


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## fowltalk (Jan 28, 2007)

u dont see that very often in ohio...either thats an early eightys rig or its been submerged most of its career, maybe both.....sandblasting will work just fine. that doesnt look that badly pitted atleast above the cavitation plate....he can blast it on the boat dont take it apart unless u are servicing something....immediately after blasting it, spray it with "self etching primer" (green) and black epoxy paint as the top coat.....buy the self etching primer in an aerosal can (walmart, autozone)....made by Rustoleum....its remarkably high in solids & a great product.....one $5 can will do that whole pig.
dont prime or paint the anodes or they wont work properly.

let me know if i can help u further....


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## ErieRider (Mar 23, 2010)

Looking at the limited picture from the boat it looks like the boat is fiberglass. From the pics it would be my guess that the anodes may not be the correct anodes for your water type. Normally on fiberglass in freshwater Magnesium anodes would be the choice. From the pics it looks like the anodes are in to good of shape and may not be sacrificing like they should. Possibly is there Zinc on there from a previous owner or something? If you pull one off it should have a quicksilver number and a internet search of the number may reveal the material they are made of. Just my 2 cents to prevent the issue again.


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## little d (Dec 10, 2008)

Your right its a 1995 23 proline. the boat looks brand new compaired to the outdrive. The guy i bought the boat from was the first owner in michigan and told me it never sat in the water over a weekend. Why only bottom paint on the outdrive? You said something about the right anodes, are there different ones then? thanks again for the help.


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## ErieRider (Mar 23, 2010)

Yes there is. Due to the content of the water different materials are made to protect the outdrive. In freshwater for the best protection and proper protection choose Magnesium anodes. To me looks like your anodes are not even pitted but your O/D is. The anodes should "sacrifice" before your outdrive does. I wanted to post a wikipedia article here but could not. Just google "choosing the right sacrificial anode for your boat" and the article should come up. But the short story is they should be magnesium if leaving in fresh water. Repair the O/D put on Mags. and you will be good.


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## ErieRider (Mar 23, 2010)

here is the best I can do. It is just a small portion of the article but can explain it quicker and faster than I can type. Hope it helps.

Examples
Other examples of protection by use of sacrificial anodes include protection of voids in the glass lining of mild steel water heater tanks via use of magnesium or aluminum alloy anodes,[1] protection of off-shore oil rigs via special alloy anodes for use in salt water, and on steel Gas pipelines with zinc anodes.

Sacrificial anodes are used on water-based vessels, such as yachts and powerboats, to minimize the corrosion of vital metal parts such as hulls and propellers. Conventionally made of zinc, aluminum and magnesium, boat anodes are designed for use in particular water types and with specific boat models. The number and size of anodes is determined by the type of material and the surface area being protected. [2]

Choosing the Correct Anode
Generally, boat owners should choose the anode most suitable for the type of water they berth in. Naturally, some boats will move between salt and freshwater, or be berthed in areas where water will change between brackish water or freshwater. In these cases boat owners must choose a cathodic protection system to minimize corrosion in all environments.

Not all anodes are suitable for use in every type of water. For example, if zinc or aluminum anodes are left in freshwater they will develop a layer of oxide which will stop the anode from working. On the other hand, aluminum anodes will operate effectively in brackish water while zinc anodes will become unreactive. If the wrong type of metal is chosen for the water type, the anode will become useless. [3]

Water Metal Anode

Salt Water Zinc or Aluminum Anodes 

Brackish Water Aluminum Anodes 

Fresh Water Magnesium Anodes


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## Nauti cat (Nov 30, 2009)

Erie Rider is correct mag for fresh water.


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## Nauti cat (Nov 30, 2009)

little d I dont know about Merc but Volvo told me to keep bottom paint 1" away from od


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## Classic25 (Oct 16, 2008)

Bottom paint on the outdrive in fresh water is not necessary. There are no barnacles in fresh water. In salt, there are bottom paints specially formulated for drive use, that does not have a copper component included in the paint. Copper transmits elecricity (electrolosis). Your drive, if bonded properly should not have done that. If it was bottom painted with bottom paint that was a true bottom paint i.e. hull paint, then there should be no surprise that that happened. It invited and transmitted electrical current and started cooking your aluminum away.

Blast it, etch and epoxy paint it.

Magnusium anodes. Check for continuity between mounting bolts and other metal in drive after installation to ensure proper contact.

Bonding. Check all the little stainless, and coated "ground" bonding wires connecting metal components of the engine and drive. Replace as necessary.

Your drive looks to be in decent shape.. Thats the route I'd go FWIW.

Good luck.


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