My block is drained, right?

I generally use straight antifreeze, on the theory that it is diluted by whatever water is in the block. Of course, straight antifreeze is still plenty cold resistant for our winters in NJ.

Lou C said:

Agreed, I would do that just to improve the odds so to speak.
One nice thing about having the Sierra PG stuff and the refractometer, is I can mix up custom batches of AF for just such a situation that are stronger in AF concentration. My usual mix is 50/50 with water and that gives approx -30*F freeze point.

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Well... Who knows what the ratio will be at that point, given that I don't know what I'm adding it to. I'd like to know if there's actually a problem. Now I'm curious. I don't think I'll have time tomorrow (rainy today) but I may just refill and redrain the whole system in a couple of weeks. No place to get proper PG antifreeze around here anyway. My whole boat is an experiment. I've spent more time talking about this than it would take me to re winterize it 5x.

Chris1956 said:

I generally use straight antifreeze, on the theory that it is diluted by whatever water is in the block. Of course, straight antifreeze is still plenty cold resistant for our winters in NJ.

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Point being there shouldn't be any water in the block, I'd rather know that than gamble on AF getting to where it's needed at the proper ratio

nola mike said:

Well... Who knows what the ratio will be at that point, given that I don't know what I'm adding it to. I'd like to know if there's actually a problem. Now I'm curious. I don't think I'll have time tomorrow (rainy today) but I may just refill and redrain the whole system in a couple of weeks. No place to get proper PG antifreeze around here anyway. My whole boat is an experiment. I've spent more time talking about this than it would take me to re winterize it 5x

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I’ve found that O’riellys near me actually stocks the Sierra PG antifreeze. I try to capture what I use each year to use again the next year and test with refractometer. Price isn’t terrible, $29 and it make two gallons.

Make sure you drain the intake manifold on a later 4.3L that has Vortec heads. There is a plug facing the front.

Not sure what they changed when they went to the Vortec heads and manifolds, but yes this has to be drained and there was actually a TSB put out indicating that. On my old pre-Vortec, the manifold just drains with the cyl heads....if I had to guess, it might be that since they had eliminated the exhaust cross over that the pre-Vortec had, they had to increase the size of the water passage under the carb, to keep the carb warm for running in cooler weather....the water passage on the pre-Vortecs is actually quite small, just connecting the 2 cyl heads under the ' stat housing.
On some engines it might be hidden behind the hose that feeds the manifold on that side. Likely an NPT thread, I always like to put a bit of Permatex Aviation on those to keep them from seizing.

So, interesting about this... It isn't mentioned in the manual. @Lou C , do you have a link for the tsb (iirc it was a VP tsb, not merc)? I did this a few times, and never had water come out. I also don't see what's going to freeze in there. It's a huge space that appears like it should drain completely. I haven't bothered with it in a few years. Once again I'll experiment. First "freeze" last night, had 3 hours with a low hitting 31. Won't have a chance to pull that block drain again until next weekend, if I still have the motivation by then.

nola mike said:

So, interesting about this... It isn't mentioned in the manual. @Lou C , do you have a link for the tsb (iirc it was a VP tsb, not merc)? I did this a few times, and never had water come out. I also don't see what's going to freeze in there. It's a huge space that appears like it should drain completely. I haven't bothered with it in a few years. Once again I'll experiment. First "freeze" last night, had 3 hours with a low hitting 31. Won't have a chance to pull that block drain again until next weekend, if I still have the motivation by then.

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I'll have to look around. It was an OMC TSB IIRC and Volvo also picked it up, they actually used OMC shop manuals during the joint venture era that were a lot better than Volvo manuals lol. I think it may be like this, if the engine isn't level, or not tilted down in the front, it may be possible for water to collect toward the rear of the intake and not drain. I looked at one of those intakes and the water passage area appears to be much larger than the one on the old pre-Vortec.

I took a screen shot from a VP manual for wintering, all I could find....

There are many stories of people having milkshakes and find the intake manifold cracked on the Vortec 4.3L engines.