Antifreeze in closed cooling system missing antifreeze

[DonnyT]

I have a 1992 Vovo ib-ob. It has the two cooling system where it picks up the lake water and the closed water system. Well today i started my boat up for the first time from winterization.It was over heating. Starting cheaking things and found out the resivor that holds the antifreeze was empty.I filled it up and the heating up problem was gone.But where could have the antifreeze gone. After i filled it up and ran it for awhile i recheaked it and it was still full.The only thing i can figure out is maybe the guy who winterize it drained it for some reason.any ideas will help

[Don S]

Drain both sides of the heat exchanger (that is what the reservoir is called.) Then plug the passages for the antifreeze side of the heat exchanger and pressureize it with a coolant system tester.Many time the heat exchangers will corrode through and let the antifreeze drain out when the boat is stored, then when you fill them up while in the water, they have water on both sides and stay full.