Originally Posted by MoonRiver
Ok, what is a "half closed" cooling system?
Yep, I learned a lesson this winterizing year too. While I thought the engine was warmed up enough to allow the Pink to flow through the block, it wasn't. When I shut it down and started opening the petcocks only clear water came out!!! Its a good thing I always drain the block, PS cooler and manifolds after flushing with pink.
A half/partial closed cooling system only cools the engine through a heat exchanger while a full closed cooling system cools the engine and exhaust manifolds, the elbows are still raw water cooled.
This closed loop through a heat exchanger is filled with an antifreeze mixture just like a car. The only difference is the HE on a boat is liquid to liquid while a car is liq to air. In other words raw water flows through the HE to remove the closed sides heat.