outboard engine and salt water

[ted]

have inherited recently an 8hp tohatsu outboard engine. good mechanically and runs well - no doubts about that!problem is that the salt where the outdrive goes into the water is showing deteriation through the salt water effecting the aluminum. however, the casing is still sound but needs 'patching' or repairing before further deteriation. a winter job!can anyone recommewnd the best way of doing this - preferable to get it back 'shining and gleaming like new'.ted.p.s. i am not representative of beatons but like most this excellent boat yard is 'home from home'. after all this is where we keep our most important asset - after the wife that is!!

 

[Bob Howie]

Salt Water

Is it salt water corrosion or electrolysis? Does your outboard stay in the water or do you raise it up when docked? If it is staying in the water, you're probably noticing the effects or electrolysis and most marine supply stores have zincs that attach to your outboard's lower unit to prevent this problem.Also, if your lower unit is letting water into it through holes or something like that, you need to pay some immediate attention to this problem. No water should be inside the lower unit housing because the lower units are normally sealed and filled with lube in much the same way the rear end in your vehicle is sealed and filled with lubricant. No lube and you stand a good chance of eventual failure of the lower unit -- a pricey fix.If you simply have corrosion, then I would recommend you use a wire brush to remove the corrosion, maybe even a follow-up to the brushing by using 220 grit sandpaper or finer to "burnish" the aluminum and give it a little "tooth." Then, treat the area -- most likely the entire lower unit if it were mine -- with zinc chromate...which is normally used on the aluminum surfaces of aircraft prior to painting to prevent corrosion beneath the paint...and then a good quality paint such as Rust-Oleum over the zinc chromate. That should give you good protection of your lower unit and an occasional spot-checking to make sure you're not revisiting the problem in the future...which you inevitably will.Hope this helps.

 

[Ray Bowles]

Ted, Just a guess, what are the anoids like?

Is the outboard being sacrificed to satisify the needs of the rest of the boat?As I say, a guess.RayS/V Speedy

 

[ted]

filler

thanks for your replies.can you also tell me the best way to fill those pit marks that have occurred before using the zinc chromide, etc.

 

[Bob Howie]

Filler material

Ted, you might think I'm a little nuts, but there's a product at your marine store known as Marine-Tex. While it's not fully intended for the purpose, it's very versatile material and once it sets up, brother, it's harder than concrete! I know of a case where a guy fixed a crack in his block with the stuff and then used a cylinder hone to smooth it out, put the engine back together and it ran pretty much ok. It's a two-part mix and you have some working time with it. I would use it like body putty -- Bondo -- and use a plastic squeegy to make sure you get it in the pits and to get it as smooth and as flush with the surrounding metal. I would try to work it as carefully as I could because once it cures, it'll be pretty tough to sand. It's pretty waterproof and the pits, by their nature, are going to have some "tooth" to them so the material can get a grip and hold on once it sets. Now, this is a little weird, I know, but I think it will work. I would do it to my motor under same circumstances. Once the stuff cures and you've gotten it pretty smooth with the surrounding metal, you'll be able to paint over it ok.By the way, it's Zinc Chromate; not Chromide...just saying that so you won't go off looking for the wrong stuff. Use a couple of thins coats which is better than just one heavy one but be sure to cover the metal completely. Let me know how things turn out.Also, be sure to check your anodes like the other post suggested. It sounds like to me that you are getting some electrolysis damage, so just be on the safe side you want to check that.Regards,Bob