Painting my lower unit on my Johnson suzuki

[w2much]

Not certain where to post but it is a Johnson motor. Or not.I have had a few of these motors. They do not seem to hold up in salt water very well. I need to paint the lower unit as I have done on others in the past. Not real happy with the way the last ones have held up so I have some questions. I have some water based bare aluminum paint made by rustoleum. I am thinking to use it. Zinc chromate takes forever to harden and is 14.00 a spray can. Has anyone used the rustoleum ? Next is the paint coat. This lower unit has already been repainted, maybe twice. Once appears to be a copper based anti fouling bottom paint. Mixed metals ? The other coat seems like a thick epoxy. There is a lot of pitting, the thick epoxy will fill. The copper bottom paint is expensive. OK, now you know I am thrifty, but I do not want to waste my efforts. Any good suggestions to fill the voids and get a good coat of paint to stick
Thank u in advance for your responses.

 

[GA_Boater]

All I can offer is - Don't use copper based paint on aluminum.

Strip all the anti-fouling coating off if you don't want more pitting. Copper eats aluminum for breakfast, lunch and dinner.

Sometimes being thrifty can be more expensive in the long run in some instances. Use good coatings even if they cost more.

 

[w2much]

The Rustoleum is called Latex Aluminum Primer. Says " for the ultimate finish on aluminum or galvanized surfaces. Looking for opinion or advice on it. The copper bottom paint, can I paint over it to stop the electrolysis?

 

[GA_Boater]

If the paint under the copper bottom paint had any scratches or worn spots, the copper is on the aluminum. That's why I said to remove it. Salt water, copper and aluminum just don't work well together.

Do you moor or trailer? A trailered boat shouldn't need bottom paint.

I seem to remember some guys tried the latex primer and it didn't work well. I wouldn't even try latex paint of any kind on a boat, but that's my preference.

If you don't get some other members commenting, it may be a good idea to move this to another section. I'll keep an eye on the thread and move it if it doesn't pick up. Only a couple of hours old now.

 

[w2much]

Moving is fine. Just did not know where. Yeah, the aluminum is well pitted. I will do what I can to mitigate the issue. Incredible that in trying to keep the lower unit in decent shape it was unknowingly set to a death march. I just want to do the right thing ,not the wrong thing.

 

[Sam2001]

Strip as much of that old paint off by sanding , wire brushing etc. , then get some cleaner that takes of any grease or oil and pressure wash with low pressure . look in to Inter lux coatings and don't skip the primer. They have some of the best marine coatings, it shouldn't take much probably a quart of primer and top coat . I'm not sure how bad that pitting is on your motor but i wouldn't be concerned about it , the right paint will fill a lot of that in. I boat in a salt water environment as well , it does wear on these motors pretty fast , especially when the coating is gone.

 

[Vic.S]

Moving is fine. Just did not know where. Yeah, the aluminum is well pitted. I will do what I can to mitigate the issue. Incredible that in trying to keep the lower unit in decent shape it was unknowingly set to a death march. I just want to do the right thing ,not the wrong thing.

To successfully paint aluminum you need to remove all the oxide from the surface including from the pits. Grit blasting with soft grit is about the only way to do that

You should remove all the old copper based anti- fouling paint and if it is necessary use one that is suitable for use on aluminum. For example Interlux Trilux 33 but remember that the antifouling paint contributes nothing to the protection of the metal. It is purely there to prevent marine fouling if you leave the engine mounted with the lower unit submerged.. If you lift the engine from the water when not in use it is not needed at all.

 

[Scott Danforth]

if your pitted, you have to blast. no way around it

you need a good acid wash of the bare aluminum

a good zinc chromate etching primer

a good 2-part paint

bare aluminum and copper bottom paint is called an eveready battery. your aluminum lower will literally dissolve in no time. remove it

if your pitted too deep, you need a new lower.

thrifty and boating are opposite ends of the spectrum.

 

[racerone]

It is very hard to match " factory painting technology " with a $10 spray bomb.

 

[w2much]

I guess I will remove all of the paint to bare metal where needed. What a pia . I might have another lower to swap out, but it is on a long shaft engine. Hopefully the driveshaft pulls out. Might an older 9.9 OMC 2 stroke lower unit fit this Johnson/Suzuki ? I will find out today. A lesson to all regarding copper based paint on a lower unit. Thanks for all of the input. I appreciate it.

 

[racerone]

I do not believe an older 2 stroke unit from a Johnson will fit that 4 stroke !!

 

[GA_Boater]

Seeing that you're getting advice, no need to move the thread.

I didn't see if you trailer or moor the boat. It makes a difference if anti-fouling is needed or not.

 

[w2much]

Boat will be trailered. I removed a few 2 stroke lower units before dark. I am going to check Co patability on Sunday. I will post results.

 

[racerone]

Me thinks they will not work !

 

[w2much]

Acid wash would make it clean. I use lime away but thanks to your post I remember that I do have some acid which I purchased a while back for cleaning aluminum. I forgot all about it.

 

[w2much]

Racerone, The 2 stroke omc's 9.9 to 15 Hp that I have have two types of spine on the drive shaft. Some have the square four spine, some have the round 9 or 10 spine. I looked up part numbers on the round ones even measured ect . Part numbers are different but the shafts are the same . So I have an E15RCCS 1988 2 stroke which I am switching driveshaft and lower unit with the J10FREDC 1996 9.9 4 stroke.Me thinks (and hope) it will work.