Has anyone had problems with their outboard engines water systems getting clogged up with scale? I had just launched the boat and as I was motoring to the dock I noticed the water coming out of the engine has turned to steam and smoke. I changed the water pump, but no water was coming out. I dropped the lower unit again and blew high pressure air into the water outlet. All kinds of junk came out!! All is well now, but is there anything I can do to flush the engine of all this scale? I was thinking of mixing some radiator cleaner in a bucket, drop in a little pond pump, and pump this cleaner through the engine for a few hours/over-night. Any ideas?? The engine is a 4hp Mercury 1972-74 vintage and runs great. Thanks, Jay Beery