I know you guys love these "after winterization cracked block questions" but here I go! 1989 mercruiser 5.7 350 magnum with through hull exaust. took boat out of storage, went to change plugs and had winterization antifreeze in my #7 cylinder. Changed oil and there was not a drop of water in it. Cleaned all plugs (none of which had any water) and fired it up. It ran great. after about 15 minutes I shut it off and pulled the plugs. No water in any of them. Let it sit and checked again, still nothing. Three days later did the same routine and nothing again. Have dog house and all seats out of boat now and don't know what to do? Thankful for any help you can give....