I have a 96 classic 22 with a 454 mag L29 block with stainless marine headers system. The motor is a Mercury Marine reman. from 2002 and with 73 hrs on it. The boat was not used from the 4 th of july to labor day and when it was started up, there was a dead miss on one of the cylinders. new plugs helped some but a water test revealed a problem. Further checking revealed that #3 plug had water droplets on it and the exhaust valve was found stuck open after a compression test. all other cylinders were 120. bore scope comfirmed the open valve. removal of the valve cover produced a broken pushrod for that valve also. Pulled the motor out of the boat today and removed the header/manifolds. and found salt/water slimy solution in each port of the manifolds on both sides and the outside exhaust ports of both heads were rusty and had water droplets in them and on the valve face. The center two ports were whitish in color with the #3 port being just about normal in appearance. It was evident that there has been a problem for some time. I have not used the boat for more than 4 hrs since purchase and it ran fine on a water test and the last time it was used on the 4 of july. tested the header manifolds with 40 lbs of water pressure and cannot fine a leak! Anyone have an idea on this one. My first thoughts are a header problem with too much cam but its mercury stuff as far as I know. It did idle nice and did not sound over cammed. I will remove the intake and heads next to see if that reveals anything else. What else could cause water in all of the cylinders?? I cannot figure where the water is coming from if not a header issue. I have not heard of such a problem with stainless marine'