I installed little ball valves, instead of the plugs. Now, when I want the drain the manifold and the heat exchanger, I just open the valves and let the water drain out. I also use my boat during the winter, so this is the easiest way...
Hey I have a mercruiser 3.0L can you post a pic or a link of what you did.. I will be using my boat all winter as well... I am new to the inboard winterizing thing...