I have an Indmar MCX in my boat. I noted the other day that my exhaust manifold has some corrosion on it. It is occurring in these small little "caps" that have been welded into it. I think they are referred to as a sacrificial anode, but am unsure. In talking to Indmar, I'm told that this occurs because of electrolysis - the water interacting with the aluminum. He more or less implied that i should be draining the block after every time I ski. No one I know does this except at the end of the year to winterize their boat so the comment struck me as....odd. One of the caps corroded through the other day. I temporarily repaired it by slopping some JB Weld onto it.
The guy from Indmar further states that I should remove the manifolds, have them drilled out, and then have new caps welded in. Or, I can spend approximately $1,100 and get a new cast iron exhaust manifold set. I have no idea what kind of costs I'm going to run into having the manifolds, drilled, welded, and repainted only to have this happen again in approximately 6 or 7 years (my boat is an 05). Has anyone else experienced this? What did you do to correct the problem? With all the aluminum blocks out there now, will this be an issue for them as well?
Additionally, I'm concerned that because Indmar changed the exhaust in 06, that I'm going to have ECM issues with the cast iron exhaust (should I go that route). Is this concern unfounded?
thanks in advance for any insight or direction you can provide!