Anti-freeze vs draining

[Crazer]

I was wondering today why anti-freeze is run through engines to winterize them. There must be some advantage over simply draining the block, but what is it? It was on my mind because my block was drained by the marina this year as the engine was not running when the boat was put away. Anything I should watch out for during spring commissioning?

[hanleyclifford]

The problem with simply draining an engine to winterize it is that in fact the engine cannot really be completely drained. Residual water especially in the bottom of the water jacket at the base of the cylinders remains and reacts with the casting until it really is dried up. This area is actually where most block failures occur where the jacket rusts right thru to the cylinders. In the best of circumstances raw water cooling is long term mechanical suicide for an engine, but putting it to bed wet is like putting it to bed with a dose of poison. Fill your block with automotive antifreeze every winter.

[Crazer]

Originally Posted by hanleyclifford

The problem with simply draining an engine to winterize it is that in fact the engine cannot really be completely drained. Residual water especially in the bottom of the water jacket at the base of the cylinders remains and reacts with the casting until it really is dried up. This area is actually where most block failures occur where the jacket rusts right thru to the cylinders. In the best of circumstances raw water cooling is long term mechanical suicide for an engine, but putting it to bed wet is like putting it to bed with a dose of poison. Fill your block with automotive antifreeze every winter.

Good enough for me!