Painting a new transmission

Talisker361

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Jan 16, 2021
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2
Looking for some advice on painting a new transmission for a sailboat.
it’s brand new fresh bare aluminum.
it’s not going to be immersed in salt water obviously, so it should be reasonably dry but it’s a boat so..... u know
Any tips on getting a half decent paint job with rattle cans ? Outside of the normal - get it clean as possible, make sure it’s warm etc. I read some posts about using vinegar and water to clean aluminum ? I was going to use acetone to clean it. It’s very clean but people have handled it.
In terms of a primer I was leaning towards a self etching primer vs zinc chromate which sounds like it’s nasty stuff.
I have proper respirator but not a full face just half mask.
 

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matt167

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Sep 27, 2012
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Just some prepsol/ wax and grease remover and then etch primer

Rustoleum is probably the nicest spraying paint you can get in a can. It's an enamel so it's tough
 

gm280

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Jun 26, 2011
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Since it sounds like it will never come in contact with water, most any type paint should suffice. I would use the same type paint that you plan to use for the primer. In other words, if you go the Rustoleum route, use Rustoleum primer as well. That way they will be perfect for each other. And yes acetone will clean the metal perfectly before priming. JMHO
 

76SeaRay

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There is a write up on here on painting Mercruiser outdrives starting with Alumaprep and Alodine on bare clean aluminum as a bonding agent. Good information to consider..
 
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Talisker361

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Jan 16, 2021
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Sounds good! Thanks for the suggestions
I have a can of Westerbeke paint that’s matched to colour of the engine so I was going to use that for the actual paint I was mostly worried about cleaning and primer type and if I need to do any other prep work
Going to a lot of effort to put in a new transmission so I want to look nice years from now if and D678B81E-8FC4-497C-A84B-9CF0898D67D9.jpegwhen I go to sell the boat
There is a write up on here on painting Mercruiser outdrives starting with Alodine on bare clean aluminum as a bonding agent. Good information to consider..
yea i read that, seems like that’s the best way to do it using alodine and then zinc chromate primer but there was a lot of comments about how nasty that stuff is so it kinda turned me off using it. Plus this won’t actually see any salt water just more a humid salt air environment
 

76SeaRay

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Not sure if you will be able to find zinc chromate primer... Some have suggested that putting zinc under paint can lead to corrosion under the paint if you get a chip in it as the zinc will react... I am going to be doing my sterndrive soon and planning to follow the write up using the alumaprep, alodine, epoxy or urethane primer, and then epoxy or urethane top.
 

gm280

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Jun 26, 2011
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AH, Zinc Chromate isn't any harder to locate then any other type primer. I used Zinc Chromate on my bare metal Johnson engine and then used two part PPG high build primer on top of that. Then base color and clear coat. And it worked perfect and looks great. Zinc Chromate is used in a lot of Military aircraft because it works extremely well bonding to the metals. If it is good enough for the Military, it certainly is good enough for me as well. And for the record, any paint fumes breathed in is bad for you. Zinc Chromate isn't any more or less toxic then any type primer. Use the proper PPE equipment and go for it... JMHO

Primer -  (41).jpg
Everything covered in Zinc Chromate primer...
Painted -  (22).jpg
 

alldodge

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Don't forget to protect against galvanioc corrosion. Guessing your going to use steel bolts to mount the trans and motor together. Look for dissimilar metals and coat surfaces and fasteners accordingly
 

dingbat

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Nov 20, 2001
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Not sure if you will be able to find zinc chromate primer... Some have suggested that putting zinc under paint can lead to corrosion under the paint if you get a chip in it as the zinc will react... I am going to be doing my sterndrive soon and planning to follow the write up using the alumaprep, alodine, epoxy or urethane primer, and then epoxy or urethane top.
Alodine is far nastier than Zinc Chromate
 

todhunter

Canoeist
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Sep 15, 2020
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Just use the proper PPE and you'll be fine. I've used alumaprep / alodine / zinc chromate a bunch in experimental aircraft construction. That combination does work well for protecting aluminum.
 

mickyryan

Rear Admiral
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Apr 18, 2016
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4,210
def need etching primer or the paint wont stick it will peel pretty quick, here in fla they have two different suppliers for screen enclosures one does zinc chromate on all the metal then paints other dont, in a year or so the other is trash anywhere near coast.
 
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