I have a 1990 WellCraft 230 Coastal with a 5.7 Mercruiser and an Alpha One outdrive. The engine overheated last weekend while trolling with the main engine. Temp guage read about 190 to 200 deg. Had some blue smoke coming out of the breather tubes just prior to me shutting the motor off. I figured the impeller in the outdrive is junk, and plan on replacing it. I am wondering if there is anything that I need to look for as far as damage from overheating? Buddy told me that rings have been known to fuse to pistons? Also something about lead plugs in the block that melt if the temps get too high? I plan on changing the engine oil too after she started smoking. Any thoughts?