drains are located on the side of the block down low. one right in front of the starter. the other is on the other side same essential place. don't open the drain petcocks. remove them. then stick something coat hanger sized up thru them to unblock the drain passage. if your gonna do antifreeze, leave the drains out, or loose. put some in. pull drain and see if you get antifreeze. if so, you are sure there aint no pocket of water down there...but once you know the engine, exhausts and hoses and coolers are empty, I cant justify closing everything up just to put 50 bucks of antifreeze in there to dump out in the spring. 1 gallon in the block itself? I can see that.

You have the northern version to a T. Only thing to add here is pull the Tstat housing and fill the block with "real" antifreeze. 30+ years of boat winterizing here in the near north and never a problem. People that are willing to cheap out on a few dollars for the extra measure are the fools that find themselves with a cracked block come spring. Few bucks for antifreeze vs many bucks for new block? Brain dead simple to me, drain into a bucket in the spring, run thru a strainer, recheck the strength next year and reuse it.

My present boat is closed cooling and I still run the antifreeze thru the sea water portion every year. I sleep just fine on those nights mid February when the temp dips to minus 35.

Very old saying,,,,,,,,,,,,,,, " An ounce of prevention is worth a pound of cure!!! "

Pluz, t-Stat needs pulled and inspected or rust flakes chipped out every year anyway. But make sure you see-feel the drains drain empty. Then pour in antifreeze and you should be able to taste it immediatly oit the drain. Now you can fill block with antifreeze. My water pump hose method is not as thorough, but sometimes the drain plugs are flat out inaccessable.

I think ours is 1/6 or 1/4 hp. That's more than enough. We usually buy 10 gallons of coolant. Fill the Rubbermaid container with 5-6 gallons to start. Start your pump then fire the engine. Should be able to run it for 5-8 mins before it starts to heat up the coolant. Once the t stat pops you are good. Fog it and your done.

been doing it like this for 8-9 years. Never had an issue. Not a fan of the drain and pour into the t stat. Nor am I a fan of running the engine on a jug of coolant. That jug goes fast and you don't know if the t stat pop or not.

Doesn't Peak or someone make a 100% enviro friendly automotive grade anti freeze... I remember seeing commercials about it.

It is this here - Indmar in their close cooled apps use to recommend this exact brand as we followed their OEM recommendations. I currently see the pricing all over the place - 25 bucks to over 100 bucks.

https://peakauto.com/products/antifr...motive/sierra/

Sorry for bringing up an old thread but have been meaning to post pictures of our winterization setup. Some people had questions. This should help.

The image below shows the Rubbermaid catch container with a sub pump. The sub pump ican either be routed to muffs or the fresh water pickup. We use the fresh water pickup. Easier and less leaks.

we also have the luxury of using clear tubing to catch antifreeze as we have dry exhaust. Will show another image for people who have wet exhaust. Anyways process is simple. Can run engines for minutes on end ensuring antifreeze is in the system. We do this from a cold start up. Works perfect.

For people with wet exhaust. Can make up a simple pvc setup with rubber slip fittings and hose clamps. Hose clamp them to exhaust. Position them into container and your done. Simple and easy.

I ended up using this setup.

Nice setup!!! Similar to ours. Hope my suggestions helped.