Winterizing an inboard

It depends on your cooling system. a standard, basic cooling system has sea water cooling the block and heads etc. The more expensive system has those components cooled with a heat exchanger, like a car, with antifreeze/ corrosion inhibitor.

For the former, you need to be sure the thermostat is open so the block/ head have antifreeze in them . Most US forums advocate taking the thermostat housing off to do this. Foer the exact procedure go to iFourwinns.com, LouC will give you the answer !

For the latter, just run some antifreeze through the cooler; either via gravity or via muffs on the outdrive.
 
If seawater cooled run it in muffs until thermostat opens. Then run a 50/50 coolant/water solution also through the muffs (commonly possible from a can via standard garden hose connector).

This way water jacket, impeller pump and exhaust will be protected.
 
Its also a good idea to run fogger oil spray into the barrels and drain exhaust manifolds and risers. Empty all water hoses. Personally I'd drain the block everytime. Air doesn't freeze and antifreeze is good only to -20C. There were a couple of mornings in Dec circa 5 years ago we hit those temperatures.
 
??

I'd leave the coolant in to benefit from it's anti corrosion properties.
On my can (ethylenglycol based) it says 1:1 protects to -38C. Over here we do get cold days during winters but -38 still leaves a good margin (by far..)
 
If yours goes to -38 then you obviously dont have a problem. Most do not, the OP can determine. But at least give him the knowledge to make an informed choice. And cast iron doesnt really corrode. Raw water cooled engines are testament to that.
 
Sorry to disagree. Cast iron corrodes and this is why fresh water cooling is used, especially in salt water. Manifolds are replaced regularly due to corrosion because hot sea water is even worse. The anti freeze properties are of minor importance when the boat is out of the water because the system drains though the sterndrive, but to eliminate risk for whatever may stay inside the frost protection and preserving properties are desirable.

I agree that the OP should make an informed choise. The owners manual may help in this regard.


If you were right fwc or stainless/aluminum manifolds would not exist. Ever seen a sea water cooled boat in the Med where salinity is high?

FWIW Mobil Antifreeze in the UK states dilution ratios:
Antifreeze + Water : Freeze Protection
33% + 67% : -18ºC
50% + 50% : -36ºC
60% + 40% : -52ºC
 
Cast iron forms a coat of oxidation in much the same manner as galvanising. Take all the piers for example, still standing a century plus on. Corrosion, negligible. Raw water engines suffer from cooling and heat issues. Blocks never corrode through. That's a myth.
 
Hi guys, thanks for the suggestions so far.

So you know, the boat is currently in cardiff marina which is a rinker 27. The only way to do this is boat lift which is £170 lift out and another back in.

Wasnt sure if there was a way of doing this while in the water. If not, is there any other way of protecting the engine. The boat is in fresh water so you know.
 
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