winterisation - retained water in the cylinder heads?

[oGaryo]

got a little niggle that may see me back at the boat to redo the winterisation of the engine... it's a 5.0l MPI that I've drained using the single point drain system removing the blue plug from the thermostat housing in the process to aid water flow out the engine... did this whilst the engine was cold.

Then hooked up a 20l mixture of antifreeze to the sterndrive and ran that through the engine after closing the single point drain system and replacing the plug in the thermostat housing.

ran enough through to fill a couple of buckets with antifreeze flowing out the transom exhaust outlets.

what's niggling me is I can't recall if I should have run the engine up to operating temp first before draining the water off initially.. by not doing so, have I left none antifreeze treated water in the cylinder heads on the assumption the thermostat would not have opened in the few minutes the engine was running whilst being flushed through with anti freeze?

thanks in advance for your advice.

cheers Gary

 

[Burnham Bob]

must admit i always did run the engine up to temperature to open the thermostat when i had a raw water cooled engine.

i always thought the advice to just run a bucket of water through it then the antifreeze would cause exactly the problem you are talking about. i had a vetus water strainer that you could take the top off and used a garden hose with an on/off lever to supply fresh water for cooling until the engine was warmed up and then finished off with two 2 litre coke bottles of 50/50 antifreeze and stopped the engine when the last of the anti freeze could be seen through the pipe as it was about to enter the raw water pump.

mind you - doesn't the thermostat just close off the inlet? the water in the head surely should have drained out the other side........(help from the experts please!) but i would have thought that its unlikely that the water channels were filled to capacity with water with no room to expand if and when it freezes