Draining block - Leave open or closed

I am new around these parts having just bought a supra.
However I have been winterizing boats and jet skis for 15years.
It doesnt realy matter about if you drain the antifreeze or not I have done both and am yet to lose an eng to ice.
Good Luck

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Originally Posted by wotan2525

I've been using RV antifreeze (and not draining it) for 10 years in northernish WI where we see an honest -25F every winter. Never had a problem. Everyone seems to have their own method, but I'm going to stick to mine. ;)

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Same here. I'm in WV and the boat stays in my garage under cover, although not heated it does not get as cold in the garage as it does outside. The first year I placed a drop light in the bilge to create some warmth, but haven't done that for years.
My procedure is to drain all the water from the block and manifolds, then back the trailer down a steep bank near my driveway to drain the water out of the exhaust pipes below deck. Then I remove the hoses from both sides of the trans cooler, and the supply side of the raw water pump. Those hoses I drain and leave off for the winter. Also I remove and drain the sea water strainer basket. Then I remove the impeller and coat with oil to "relax" the rubber veins - the raw water pump is also left out. Then I remove the plug from the "J" pipe that supplies the water pump, allow to drain and re-install the plug. Then I pour RV antifreeze into one of the manifold hoses until it just starts to come out the block plugs, then I re-install the block plugs. Then I pour RV antifreeze into the manifold hoses until it starts to come out the manifold drains, and re-install the manifold plugs. All this takes about 2gal of antifreeze. Then I reconnect the manifold hoses and clean up the bilge. Close it up, clean it up, scatter some scented Bounce dryer sheets around the cabin and under the seats, and cover the boat. All set for winter . . . .

You guys all do far more work than I do.

I've got a hose T and valves @ my raw water intake. Here's my procedure.

Run engine on hose until warm. Shut off. Change oil, spark plugs and pull thermostat. Remove air cleaner. Disconnect house from supply and put in 5 gallon bucket full of RV antifreeze. Suck 4 gallons through and then empty 5th and 6th gallon into bucket while it's still running. Raise revs slightly and fog out engine through carb until it's ready to die. Time killing it with antifreeze almost being gone.

Antifreeze starts coming out the exhaust after about 3.5-4gallons have been sucked. I use 6 just because that's how many come in a carton.

I don't pull any freeze plugs or anything else. This method is simple and it works.

Here are some facts about propylene glycol

Propylene glycol antifreezes are designed to provide burst protection to temperatures of -50° F or below. Ice crystals will start to form in -50 RV Antifreeze at temperatures around +10° F and will appear to be solid ice at around -10° F to -15° F. Propylene glycol based antifreezes continue to contract and will not expand until temperatures of -50° F are reached, thus providing burst protection for pipes.

There are several methods used by the marine dealers to winterize. You should refer to your owners manual for winterizing tips and recommendations. Some dealers use a VAT method where the outdrive is lowered into an antifreeze solution and the engine is run for a few minutes at operating temperature, making sure all the water is purged and the antifreeze solution is throughout the system. Another method requires the removal of the thermostat, opening of all petcocks to drain water from the engine block and then pouring the antifreeze into the engine block until the solution runs out of the petcocks.

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