Summary for painting an aluminum outdrive Discussion
Painting an aluminum outdrive is the core issue here: the questioner wants a preferred method for refinishing Mercruiser lower units after bead blasting, but needs an air-dry process because there is no oven available. The drives are aluminum castings that spend long periods submerged, so durability matters. In the excerpted answer, Jake Koch says he has tried spraying zinc dust over the raw, cleaned aluminum surface and then applying a two-part urethane topcoat. He notes that this approach avoids the lengthy sanding and recoating process associated with epoxy primer. The thread is brief and does not present competing methods in the excerpt, but it does point readers to a related discussion on painting a cast aluminum boat sterndrive.
Q. I would like to know of a preferred method of painting my Mercruiser outdrive lower units, which are aluminum castings. If you are not familiar with sterndrive power on boats, they are the used to transfer power from the boats engine(s) to the prop(s) and are usually remain submerged (in my case, in fresh water for 6 months each year), or in southern climates, a year or more in salt water. My drives are currently in a shop being bead blasted to remove all paint.
Because I don’t have access to a oven, the process would have to include air dry times between processed elements.
I have tried using zinc dust
⇦ on
eBay or
Amazon [affil link]
sprayed over the raw and cleaned aluminum surface, followed by a two-part urethane topcoat. You’ll eliminate the lengthy sanding and recoating process you have with the epoxy primer. Good luck.
Jake Koch
G. J. Nikolas &Co.,Inc.
Bellwood, Illinois
2002
Ed. note: Readers may also be interested in letter 29978, “Best way to paint a cast aluminum boat sterndrive”