Heat exchanger -to drain

[Tony Wilcox]

Hi Gordon,I have a Yanmar 3JH2E on my boat. I want to replace the antifreeze in the heat exchanger. As I have antifreeze in the engine raw water chanels (winterised) there are many drain taps on the engine block, some with a tap and others with a knurled nut with plastic drain tube attatched. which ones will drain the heat exchanger? As I do not want to empty the antifreeze from the raw water engine jacket.Many thanksTony Wilcox

 

[Gordon Torresen]

Winterizing

The best way to winterize the sea water side of your cooling system is to shut off the sea cock, remove the hose (maybe the end on the pump) and stick it (or another hose) into a bucket that has potable antfreeze. Start the engine and run it until the antifreeze is seen coming out the exhaust hose. This will not only take care of freezing in the heat exchanger but will winterize the water pump, the muffler and anything else in the sea water circuit. After the boat is hauled, open the sea water cock to allow it to drain. Reconnect the hose and you are ready for spring, as far as the engine winterizing goes. When you start the engine in the spring, the antifreeze used will be pumped overboard but it will do no harm to the environment because you used potable antifreeze.