Originally Posted by gonesailing13
Possible problem, added coolant to the engine which was a little low. Brought it to the top,yellow coolant and ran the engine for 30-40 minutes. Checked the coolant level again and noticed it was full but with what looked like sea water. Could it be the heat exchanger is shot ? Engine has about 2500 hours on it and looks like it might be the original. Only had the boat for a couple of months and just pulled the zinc out of the exchanger and to my surprise no zinc at all. Any advice would help.
I had this problem last year. I noticed it because my coolant overflow can was filling.
The sea water pressure was higher than the engine coolant pressure. When the heat exch developed a leak the higher sea water pressure filled the engine cooling loop with sea water. Picked up a pair of re-man heat exch and then flushed the engines half a dozen times with radiator flush until clean and filled with coolant.