I have a 1998 Yamaha 9.9 HT. Just below the cowl is a hole forming from the inside out. The guy I bought the motor from kept it in renfrew moored 24/7. I was told by the local marine mech that salt water is being trapped inside and corroding it out. Is this doing any serious harm? (mech didn't know this answer) or is it just the exhaust chamber corroding and not to worry? I'm sure I'm not the only guy with this problem...If I have to re/re the powerhead I will..but if it is just a cosmetic issue..I don't care. Thanks for any input.