There should always be water in your exhaust manifolds. Whether or not the thermostat opens, you always have water flowing through your manifolds, up your risers, and out of your exhaust. When you drain the water out of the manifolds, you may have to take and stick piece of wire or some sort of pick and bust loose any rust that may have accumulated over the drain port so the water can drain properly. Failure to do this will cause cracked manifolds in the case of a hard freeze. Do the same as mentioned above to both sides of the block as well. If you have to, you can double check all the water is out of the manifolds by loosening the hose clamp and pull the water lines off the manifolds (Note: you can also do this method instead of pulling the drain plug out of the manifold to drain the water). If no water comes out there, then your good to go.
Last edited by 9Drozd; 10-03-2012 at 2:33 PM.