Outdrive corrosion

[jnb]

I have a 2005 5.0 GXI duoprop used in salt water. Over the last few years the outdrive has been suffering from corrosion despite normal anode wear. When I walk around the high-and-dry where it has always been kept, I see a lot of other Volvo outdrives in the same or worse condition (but very few Mercruisers) and mechanics tell me this is common with Volvos. Some owners tell me they have had theirs repainted professionally, but it just started corroding again a few months later. My question is, if you have had this problem, were you ever able to successfully keep it repainted and how? Thanks.

 

[HorizonblueDK]

Corrosion seems to be quite "normal" on the SX drives. I sanded my SX drive down to bare aluminium and gave it one or two layers of "International gel shield" (2 part epoxy primer) and finished with two layers of "International Trilux" After two seasons(salt water), no signs of corrosion, except for the ends of the trim rams. But since they are not really connected to anything that is connected to an anode, it is clear that they corrode.

After two seasons, it needs a new layer of black paint(Trilux), since it is worn in some places, but no corrosion. For the trim ram ends, I'm investigating to see if there can be placed a small anode on each.

 

[muc]

HorizonblueDK. Wow you have really taken good care of that boat!

 

[dypcdiver]

For anyone with corrosion on the trim/tilt rams I have fitted a 19mm/ 3/4" dia prop shaft anode to mine and it seems to have cured the problem that I had with the chrome getting eaten away on the ram shafts and causing the seals to go.

 

[tpenfield]

Stainless Props ???? Dual props can be tough to maintain in salt water. . . . and even in fresh water if you keep the boat in a slip.

One thing that I tried last year with good results was to paint the props with cold galvanizing compound. The metal depletion was on the cold galvanizing and not the aluminum. This, of course is in addition to the regular anode protection.

 

[jerryjerry05]

Some times the electrical system isn't grounded right and the drive or maybe getting some low voltage through the system.
You can also be close to a 110v leak into the water.
Lived at a marina where at the other end of the marina they found a wire hanging into the water(salt) and it ate the metal on a lot of boats close to the wire.
The Mercruiser people have a system called Mercathode or something like that.
It helps stop corrosion on the drives.
BUT!!! If it's already started your probably not gonna ever stop it.

 

[HorizonblueDK]

HorizonblueDK. Wow you have really taken good care of that boat!

Thanks, I have owned the boat for 18 years now, and I do take good care of it. Never stored outside during winter, actually only polish/wax once a year, but short boating season. When I was a kid, I dreamed of having this boat.

Anyway, as tpenfield mentions, stainless steel props??!! They speed up corrosion.