# outboard with just bare aluminum?



## Guest (Nov 8, 2010)

I know racing motors sometimes are not painted. After stripping a motor with Aircraft Aluminum stripper I think I may just paint the cowl and leave the rest of the motor bare aluminum.

Anyone done this? Not a good idea? Is the paint there for reasons other then color?


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## noeettica (Sep 23, 2007)

Corrosion resistance !


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## cutrunner (Jun 8, 2010)

Most racing motors only leave the lower unit bare. Well, actually they are bare then clearcoted. I dont see a huge issue with it. Unless its an old alka-seltzer suzuki lol (someone might appreciate that joke).


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## Guest (Nov 8, 2010)

> Most racing motors only leave the lower unit bare. Well, actually they are bare then clearcoted. I dont see a huge issue with it. Unless its an old alka-seltzer suzuki lol (someone might appreciate that joke).



I thought they just left it bare from all the rough use taking them apart.


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## out-cast (Jan 27, 2009)

> Is the paint there for reasons other then color?


Protects from corrosion.


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## Brett (Jul 16, 2008)

Does it protect from corrosion?
I've had unpainted aluminum hulls that were stored outdoors for years,
and what little corrosion they developed was at places where
other types of metal were in contact with the aluminum.
Also, aluminum masts on a few of my sailboats,
not painted, minimal corrosion again.
And isn't aluminum oxide basically a tough inert substance?
So aluminum basically is self sealing?


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## cutrunner (Jun 8, 2010)

Thank you brett. Although i do understand there are plenty stainless bolts holding the aluminum together. Causing electrolysis. But its kinda gonna happen no matter what. And if you clearcoated everything it would be the same as painting it.


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## out-cast (Jan 27, 2009)

> Does it protect from corrosion?
> And isn't aluminum oxide basically a tough inert substance?
> So aluminum basically is self sealing?


Yeah, to a point. But who likes dull aluminum? Should I rephrase by saying that paint looks better than dull aluminum?


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## Guest (Nov 9, 2010)

> > Does it protect from corrosion?
> > And isn't aluminum oxide basically a tough inert substance?
> > So aluminum basically is self sealing?
> 
> ...


Brett, thanks for the reply. It made sense to me, but it's good to here explanations! ;D

I'm going to strip the motor and see how I like it. Yes, I can polish it and shoot it with a clear coat for protection.





OutCast:


In a lot of circles doing this then painting has "the cool factor". Coming from DC a few years ago Huge lifted Trucks with stacks would never ever impress a chick, but BMW's, Fast Sport Cars, Expensive SUV's and such were the ticket! Just saying


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## Guest (Nov 9, 2010)

OK, half of the motor is done and looks good IMO. 

The motor is a Tiller Nissan/Tohatsu 30hp 2 stroke with a weight of 104lbs. They used them in racing and then the EPA stepped in. 

1990's Nissan and Suzuki have the best power to weight ratio ever. I was reading about these 25hp Tohatsu Motors(Mega) almost all 1500 were sent to LA. I think they weigh close to this motor, but you can change the jets out for 50hp ones.


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## Caretaker (Jun 16, 2008)

Just to add more confusion to the conversation............ All aluminum is not created equal. I've seen jon boats, dock ladders, chairs, and a host of different aluminum items that lightly oxidize and stay that same dull gray that seems to last forever without further deterioration.

On the other hand, I've seen hardware that "looks" like aluminum form a thick white crust and eventually crack like rusted steel. We referred to a lot of this using the general term "pot metal" in the past as they were aluminum alloy castings - not the extruded/machined aluminum we see in other applications. I'm sure the alloy contains other elements that are not as corrosion resistant - perhaps more magnesium, less aluminum. With some older outboards I've seen the same thick oxidation be the culprit for popping off the paint. I'm not sure what alloy of aluminum is used for outboards, perhaps there are several depending on mfg. and year of build.

I would have great concern over not painting an outboard in the long term.


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## Guest (Nov 10, 2010)

> Just to add more confusion to the conversation............  All aluminum is not created equal.  I've seen jon boats, dock ladders, chairs, and a host of different aluminum items that lightly oxidize and stay that same dull gray that seems to last forever without further deterioration.
> 
> On the other hand, I've seen hardware that "looks" like aluminum form a thick white crust and eventually crack like rusted steel.  We referred to a lot of this using the general term "pot metal" in the past as they were aluminum alloy castings - not the extruded/machined aluminum we see in other applications.  I'm sure the alloy contains other elements that are not as corrosion resistant - perhaps more magnesium, less aluminum.  With some older outboards I've seen the same thick oxidation be the culprit for popping off the paint. I'm not sure what alloy of aluminum is used for outboards, perhaps there are several depending on mfg. and year of build.
> 
> I would have great concern over not painting an outboard in the long term.



Thanks for the info. After this is done and clean I think maybe I'll polish the aluminum and then spray with a good clear coat just to be on the safe side.


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## Brett (Jul 16, 2008)

I remember that white metal,
still see it used in cheap boat hardware.
It's called ZAMAC. ( Zinc Aluminum Magnesium and Copper)
What a horrible combination, an alloy that destroys itself
through galvanic corrosion.


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