outdrive reconditioning questions

[dpagini]

Hey All,

Looking for some advice on cleaning up my Volvo DP outdrive. I took it off for the winter, and now want to clean it up a little. Below is a picture of the drive a few weeks ago still on the boat, and I think it's clear here it could use a nice coat of paint.

So if I'm going to do this project, I need an approach for stripping it down. It's been suggested to me that "walnut shell blasting" might be an option to clean it up. I've tried to look into it a little and get some pricing, and I'm not convinced I'm going to go down that road. Has anyone heard of this method, had success with it, or have any reasons I shouldn't do this on my drive?

If I go a little more traditional, can I use a wire brush to clean this up? Any specific tool recommendations for this job? I'm wondering if there are certain wire brushes or metals that will be too abrasive?

Thanks for any help or thoughts you can offer...

DP

 

[BRICH1260]

Wow, you`ve got your work cut out for you but you have a few months. It can be done. If you are not going to blast it, do not use wire brushes. You run the risk of imbedding small steel particles in the aluminum, which will rust. Use synthetic abrasives, plastic wire wheels, sandpaper flapper grinders for the rough stuff then transition over to 3M abrasive pads, anything but steel wire. Fill any divots with epoxy , apply a chromate primer, top color outdrive paint and top off with a clear coat if desired.

 

[scutty]

I second the earlier advice not to use steel wire brushes. Nylon or sandpaper flappers work great followed up with scotchbright pads. If you break through to bare aluminum I have had good success following the instructions in the manual to use Alodine with the recommended pre-cleaner. (Check out www.aircraftspruce.com) The precleaner also does a great job cleaning a painted surface to get it ready for a top coat. I don't think you need to strip the whole drive down to bare metal to get a good result. I have *not* had very good success with zinc phosphate or zinc chromate primers. When/if I do it again I would just use whatever primer is recommended by the top coat right over the Alodine/metalprep. I did a refinish like this a 3 years ago. Now I just do a few small spot touch ups before winter lay up and my outdrive looks great. On a related subject, are you good about maintaining your anodes? I run in freshwater and I switched to Mag (vs stock AL) and that made a big improvement. Along the same lines, make sure all of your little ground wires are clean and well connected. If your anodes and grounds are not in good shape this could all be wasted effort.

 

[dpagini]

I wanted to come back to this post and share my steps and results, and I am very happy with how it came out.
After cleaning the drive all winter (lots of sandpaper and 3M red pads), I cleaned the drive with some soap and water, and dried it off. I used Alumiprep 33 and Alodine to prep the metal for primer. I used Cromax VariPrime (w/ activator) to put several coats of primer on the drive. I then used Volvo Penta top coat.

The drive looks like new compared to when I took it out of the water!

you can see some of the imperfections of the drive still in this photo. several coats of primer and paint made this look much better

finished product

Links:
Alumiprep - http://www.pilotshop.com/catalog/cspages/alumiprep.php
Alodine - http://www.pilotshop.com/catalog/cspages/alodine1201.php?recfer=6733
VariPrime - http://products.axaltacs.com/dcat/us/en/dr/product/615S.html
VP Paint - Part # 3851219

 

[BRICH1260]

Compared to your "beforehand" photo, the finished product looks like new. Good work.