1975 mercruiser 233 /5.8/351

[minn_fish]

this boat wasn't winterized, i found 2 core plugs pushed out and i have replaced them. when i started the boat with muffs on ,i found the core plugs
missing by the water that poured out the holes. now the lower hoses seem to pressurize ,but the upper hoses don't seem to have any water pressure and no water seems to be circulating to . i did detect a small leak in the area of one heat exchanger.the boat otherwise starts and runs great with muffs on. just worried about the water pressure problem.....:

[Blk-n-Blu]

Are you getting water out of the outdrive,transom area while on the muffs? are you waiting for the t-stat to open?

[haulnazz15]

Water should be flowing on the upper hoses at all times since that is what cools the exhaust. I'd check the thermostat housing/hoses for blockage.