Transom Rust with Bravo III Stern drives

[NautyDog]

I've noticed the rust stains coming from the engines on the transom (see pic). Is this a sign of a problem (i.e. galvanic corrosion), or does it just show that I worry too much and I need to clean the transom more often.

I have Twin 5.0 with Bravo III's on a 2004 280 Sundancer. The boat is kept hi & dry, and only has 170 hours on it.

 

[Henry Boyd]

With the exception of the props and trim cylinder rods, most of the exterior metal on a BIII is aluminum. Makes me wonder if the stains you are seeing are rust. We get water stains exactly the same color at our waterline. I think it is some kind of marine life/algae/crud/schmootz. Try cleaning it with one of the acid based hull cleaners (don't forget to re-wax the spots after they are clean)

Henry

 

[JV II]

Your outdrives look great for 170 hours! I bet the zincs are original since you keep it dry. Very clean. There appears to be a missing area of paint on the port drive at the trim pivot point. You should touch that up. You should have no worries.

 

[wingless]

Could it be high temperature reacting w/ salt water stain?

 

[NautyDog]

With the exception of the props and trim cylinder rods, most of the exterior metal on a BIII is aluminum.

There appears to be a missing area of paint on the port drive at the trim pivot point.

Well you two pointed out exactly why I was concerned. With aluminum Bravo III's, why would I get rust and why has the paint started to chip (it's chipped in a few other places as well). I"ve read that flaking paint is the first signs of galvanic corrosion.

I've had little luck with mechanics - even worse than greenstreak (see How stupid are marine mechanics?), and I've had great success at CSR! (some pretty smart folks here).

 

[Nehalennia]

I had the same discoloration on my 230OV with an Alpha One. I have no idea what it was from. If I wager a WAG, I'd say it was more than likely rust coming out of the engine after stopping(from the raw water side of your heat exchanger) rather than super heated Saltwater.

Yes take care of those drives. Do you leave them in the water for long periods of time?

 

[fwebster]

You are dealing with ferrous metal stains.....call it rust if you want......but it comes from the interior of the riser as exhaust water is expelled. It is inconsequential and means nothing other than it looks bad. THe easiest way to remove it is to get a mile acid rust remover like Whink (laundry product at the grocery) or Rustaid (rust stain remover from Home Depot). Both come in squirt bottles and are mild enough not to cause damage to the aluminum drives, but I would spray it on, let it sit reapply if needed, then wash off with soap and water.

More agressive cleansers are possible but not really needed and do pose the problem of spraying your transom assy's with acid.

 

[NautyDog]

Thanks!!

I have rust stain remover, but I wanted to check to make sure I wasn't just masking a more serious problem.

Kind of like the story of the guy who had a problem with his car - his "Oil" light was on. So he fixed the problem by removing the light bulb.