Well the monsoon season here in Rhode Island is finally over (we think) and only about 25% of the state remains underwater. But, today the sun came out and things are finally beginning to hop here at the marina where my office is located. So, I got my spy camera out today and caught this fellow getting ready to do the deed to his outdrive. I like his style, radio blaring, brought the lawn chair along and looking comfortable while he gets ready to do potential damage to his rather expensive Volvo Penta outdrive. We're going to have to keep an eye on this fellow probably through tomorrow because he got my attention with his moves so far, and they're some of the wrong moves.
In the above photo I see things that many people would not give a second thought to, so I have to share so you don't make similar mistakes. First off you can clearly see the blue masking tape around the perimeter of the drive unit. That tells me he's going to be applying some paint to the drive unit soon. He's been sanding away on the drive unit for the last few hours or so and I can see bare aluminum showing in some spots. Issue # 1 is the sanding itself. This drive unit is covered with soluable salts because I know the boat stays right here in salt water. If he is going to apply paint to the drive unit he needs to be certain the soluable salts are removed first if he expects the paint job to last. That means washing the drive thoroughly with a readily available salt neutralizer like Star brite "Salt Off". Sanding without washing first just drives the microscopic salt particulates into the surface of the metal. Eventually they will be the cause of a small osmotic blister that will begin to lift the paint away from the surface. Ultimately the blister will burst and expose the naked metal to the seawater. Corrosion begins right after that. So the process goes this way: Wash with salt neutralizer. Then sand loose paint and scuff surface. Solvent wash to remove all paint dust and traces of oil. Mask off areas where you don't want paint. Prime with a zinc based primer from either Tempo Products, or Moeller. (Zinc Chromate or Zinc Phosphate). Finally, once the primer dries, you can add the color coat, which is readily available for all of the popular outboard and IO drives.
Back to the tape. I can see that historically the boat's anti-foulant paint was brushed right up next to the IO drive housing. This is wrong! There should be a 1" separation between the edge of the anti-foulant and the drive housing. Since many anti-foulants contain cuprious oxide (copper based) we don't want that coming in direct contact with the drive metal, as it can induce corrosion at the interface. So when I look at a masking job for an outdrive, I want to see the tape all the way around the lower portion of the drive unit as well as where you see it in the above photo. Stay tuned, I'll check on this fellow later and see if I learn anything more about what sort of paint etc. he's planning to use.