anti freeze question

[81 Checkmate]

I will start a new thread to post the details and a video, but . . . .

I helped my buddy with a Searay 270 winterize his Mercruiser 7.4L yesterday.

We ran the engine for 20 minutes, then ran 4 gallons of -50F RV/Marine AF in through the muffs.

Then we drained the exhaust manifolds and block and water pump. As we did that, I took samples of the liquid in each manifold and the block, so 3 samples.

I stuck those samples in the freezer for the night. Freezer was -15F . I also stuck a sample of pure -50F AF in the freeze for reference.

In the morning each of the engine samples were substantially frozen - frozen hard . The reference sample of pure AF was frozen slushy, kind of like a snow cone. But the engine samples we much more frozen.

So, if you do not drain the AF, you are running a risk of a hard freeze, if the temps dip way below zero. I think many folks in Wisconsin and surrounding areas saw -40F temps last winter.

Thanks for the reply.........Just the results i was looking for.............. Now if someone could make it a Sticky and then all you have to say is... AIR DOES NOT FREEZE, refer to the sticky by tpenfield!

 

[Lou C]

The hose I am referring to will take AF as fast as you can feed it. You fill the hose that goes directly to the engine water pump. I don't know what restrictions you are referring to, (the restriction in the Tstat housing perhaps?, if so, that is not an issue because you fill the hose that you pull off the Tstat housing). Just pull the hose to the side. insert a funnel, and fill until you see AF come out the opening left by the removed hose in the Tstat housing, reattach the hose and your done. I'd imagine filling through a 1/4" hole will take some time, but to each their own. i'd be interested in seeing the pics when it is done.

I've done it this way for 15 years owning a 4.3, 5.0, 5,7, and 6.2 engines. My current boat has a 6.0l which is fully closed cooled and all I have to do to winterize is drain the heat exchanger.

Same here, this is the only way to add antifreeze that is safe, and leaves it in the engine to keep air out. You drain, poke the holes, disconnect the lower end of that big hose, then re-connect it. Next disconnect the upper end and stick a funnel in it. Then fill it with -100 no tox marine AF till it comes out the neck of the stat housing. Engine is then full of AF, no air to cause corrosion. This is the same way listed in some Merc manuals and my OMC factory shop manual. You do the same with the exhaust manifolds, just fill em till it runs out the exhaust housing on the transom mount. Last fill the raw water intake hose till AF runs out the drive water intakes.
Yes, we get it air doesn't freeze. But you all know how bad raw cast iron rusts when it was wet and then exposed to air. GM intended these engines to have AF/Water 50/50 in them all the time. You paint raw cast iron, why, because it rusts like crazy. You spray the engine with Boeshield T9 or Corrosion X because it rusts like crazy. Take a look at an engine in storage in a damp winter climate. With the temp swings we get , it will be wet with condensation in the winter anytime its damp out and the temp is above freezing.