Diesels on there own make a racket. This one was no exception. Between the motor hammering and the exhaust noise it was a real noisemaker. I looked in the bilge where the muffler was and saw that water was pouring out of it. That also meant holes in the muffler for noise to come out. This is a raw water cooled motor so the water that runs through the motor goes out the back of the boat via the muffler. Getting to the muffler is this story. There is an access plate in the cockpit floor. I thought that's where I was going to have to work from... I tried getting a hand in and down to the muffler but no go. I looked inside one of the seat lockers and saw an access panel. Down into the seat locker I went and that allowed me access to the muffler. I took it out and it wa peppered with holes. The entire unit was Stainless Steel. I thought it could be fixed. I found a welder who did SS welding and he plugged the holes but charged me an arm and a leg. Probably should have just replaced the muffler. I reinstalled the muffler and now we have a leak free cooling system.