I have a 1978 mercury 90hp. The engine pushes water out around the gaskets on the side of the engine and around the top sparkplug hole. I ran a compression test on all cyl and the top was 130 and the rest were 155. I assummed that the cylinder was cracked but after pulling the head i can not find any cracks or holes of any kind. I dont see any evidence of one either. I am new to these outboards so I dont know where else to look for the problem. Any help would be appreciated.