ike from www.Surfrc.com told me about this cool & easy trick to water proofing a servo. He of all people knows the need to keep water out of his Rc surfers servos. His surfers spend lots of time upside-down in the corrosive ocean. Check his site out for other pointers and some crazy wave jumping action! Also keep in mind that the best why to stop radio and servo problems all together is to keep the water out of the boat in the first place. But sometimes that's easier said then done.
         
          The three items you will need for this project are a thick grease, Rubberize-It Coating & thin wire. You can buy Rubberize-It at your local hardware store or we carry it here. This stuff goes a long way. And its very good for other things like coating the ends of tools and such.

         

          The first step in our quest to help water proof our servos is to take out the four screws at the bottom of the servo. After removing them you should be able to remove the top half of the servo case revealing the servo gears. When doing this be careful to take note of the gears and how they come out.

Once you remove the gears you will find some small holes.

We want to put grease in any of the holes that water may be able to seep into. Don't put too much grease because it will slow down the speed of your servo.

 

After you replace the gears, you are going to apply a large amount of grease on the gear that the servo arm goes on. This will help water from seeping into the case from the top. When done it should look something like  above picture.
 

Once the servo is reassembled, put a servo screw in and wrap a piece of wire or string around it so you can hang it somewhere to apply the rubber coating.

After the wire or string is added, wrap a piece of tape around the servo horn to protect it during the dipping process.

I use a empty box that I poke a hole in top to help keep the mess to a minimum. I apply one heavy coat. You can make it as thick or thin as you like, just add more or less coats.
 

This is a picture of a servo that has one heavy coat applied.

          Ok so its not so pretty but it does work and that's what were after. The only weak spot to this method is the grease. The more you use the servo the thinner the grease will get. Keep an eye on it and repack with new grease whenever needed. This should help with not only making your servo last longer but also keeping you boat under control while running. Short circuits from water in servos have caused me some serious crashes!