Trojan Boat Forum

Hi all,
I purschased my 1989 10.8 meter late last year and what a great boat! During my first winterizing I decided to drain the block and manifold and refill with fresh stuff since I had no idea how old it was. I found that the starboard engine antifreeze looked pretty good but the port was extremely dirty. I assume it was rust! I refilled it and figured I would flush it again at the end of next season. Once again the anitfreeze was extremely dirty so I flushed it twice with water and refilled again. The boat runs well with no over heating issues. Do you guys think this may just be years of the coolant not being cheanged? I figure I will flush again next year. The port engine is difficult to get to so maybe it was not changed often! Anyone think it could be a riser or manifold issue? No water in the oil. Boat continues to run strong with only 350 original hours.

Over years working on cars trucks and boats I have seen this all the time
I took care of a fleet of cars for a bank on would have clean coolant and another would be bad same year make and model samething with the oil . I always said no 2 engines are the same

so you think I should just flush again next year?

You can try using Distilled water ( buck a gallon at the super markit) 50/50 mix with a good coolant like prestone or peak and see if that helps
. a antirust may help but makes the coolant look milky

You may want to pull the heat exchanger on that side, and check the internal condition. It may be corroding and the source of the discoloration. If the corrosion is allowed to continue you will definitely start having overheating problems.